JPH0480394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a transfer device for transferring toner on the surface of a photoreceptor drum onto a conveyed transfer sheet in an electrophotographic copying machine or the like.

(b) Prior Art In electrophotographic copying machines, etc., an electrostatic latent image is formed on the surface of a photoreceptor drum, triboelectrically charged toner is electrostatically attached to this electrostatic latent image, and further A toner layer is formed on the transfer paper by electrostatically transferring the toner to the transfer paper whose back surface is charged by a corona ion flow. FIG. 3 is a diagram showing the configuration of a transfer device that executes the process of transferring toner onto a transfer sheet among the above processes. Photosensitive drum 1
A charger box 2 is disposed opposite to. Charge line 3 is inside charge box 2.
A high voltage is applied to the charge line 3, which is stretched over the charge line 3, and a corona ion flow is generated. A transfer sheet is conveyed from the sheet conveyance guide 4, and as the back surface of this transfer sheet is charged by the corona ion flow as described above, toner is transferred from the photoreceptor drum 1 onto the surface of the transfer sheet.

(c) Problems to be Solved by the Invention When transferring toner to transfer paper in this way, it is difficult to transfer the toner to the transfer paper after the transfer paper is brought into contact with the surface of the photoreceptor drum. desirable. This is because, by bringing the transfer paper into contact with the photoreceptor drum, the toner image formed on the surface of the photoreceptor drum can be reliably transferred as is to the transfer paper.

However, in the conventional transfer device as described above, as shown in FIG.
The back surface of the toner is charged by the corona ion flow, and a Coulomb force is generated between this charged area and the toner on the surface of the photoreceptor drum 1, causing the toner to fly to the charged area of the transfer paper. As a result, toner scattering appears on the image formed on the transfer paper, causing a significant deterioration in image quality.

Furthermore, when using transfer paper that does not have stiffness, if the distance between the paper conveyance guide 4 and the photoreceptor drum 1 is too large, the point at which the conveyed transfer paper contacts the photoreceptor drum 1 will not be stable. In some cases, a large amount of toner scattering occurs as described above, and in other cases, it is impossible to obtain an image without toner scattering, so that the quality of the formed image becomes unstable.

This invention prevents the transfer paper from being charged before it comes into contact with the surface of the photoreceptor drum, and also adjusts the distance between the paper conveyance guide and the photoreceptor drum to be appropriate depending on the stiffness (thickness) of the paper. An object of the present invention is to provide a transfer device that can obtain high-quality images without toner scattering regardless of the stiffness (thickness) of paper.

(d) Means for Solving the Problems The transfer device of the present invention is arranged such that the leading end of the conductive paper conveyance guide that guides the transfer paper to the surface of the photosensitive drum is arranged so that the leading end is approximately parallel to the surface of the photosensitive drum. It is bent so as to extend along the direction of movement of the surface of the photoreceptor drum, and the area charged by the transfer charger is regulated in front of the point where the transfer paper contacts the surface of the photoreceptor drum with respect to the direction of rotation of the photoreceptor drum. A regulating plate is provided, and a protruding guide is provided that extends along the conveyance guide and protrudes toward the photoconductor drum from a bent corner of the conveyance guide such that a tip thereof faces the photoconductor drum, and the regulation plate and the protruding guide are provided. is made of an insulating member, and the distance between the protruding guide and the photosensitive drum is approximately 1 mm.

(e) Effect In the present invention, the area charged by the transfer charger is regulated by the regulation plate, so that only the area in front of the point where the transfer paper contacts the surface of the photoreceptor drum is charged. Therefore, the transfer paper is not electrically charged before it comes into contact with the photoreceptor drum, and toner does not fly to the transfer paper, improving image quality. In addition, by configuring the regulation plate with an insulating material, leakage between the charge wire and the regulation plate is eliminated, and excessive current flows between the charge wire and the regulation plate, causing the charge wire to leak. There is no possibility that the transfer paper becomes difficult to be charged due to a decrease in the photoreceptor drum current.

In addition, since the distance between the protruding guide that guides the transfer paper to the contact point and the photoreceptor drum is approximately 1 mm, even if the transfer paper is weak (thin), the transfer paper with low stiffness will Since the paper is uniformly fed along the paper conveyance guide to just before the point of contact with the photoreceptor drum and adhered to the photoreceptor drum, images of the same quality can be obtained. Furthermore, since this protruding guide is made of an elastic member, if the transfer paper is stiff (thick), the regulation plate will be pushed and bent, and the transfer paper will contact the photoconductor drum at the point of contact with the transfer paper. come into contact with.

(f) Embodiment FIG. 1 is a schematic diagram of a transfer device according to an embodiment of the present invention.

The photosensitive drum 1 is a cylindrical body on which a photoconductive layer is formed, and is rotatable in a clockwise direction.
A charger box 2 is disposed opposite the photosensitive drum 1. The charger box 2 is made of a conductive member such as metal, has an L-shaped cross section, and is open on the side facing the photosensitive drum 1 and the side facing the paper conveyance guide 4. A charge line 3 is stretched over the charge box 2 along the rotation axis of the photosensitive drum 1. A high voltage is applied to this charge line 4, and a corona ion flow is generated.

Like the charger box 2, the paper conveyance guide 4 is also made of a conductive member such as metal. The end of the paper conveyance guide 4 is slightly bent so as to face the photoreceptor drum, and a parallel piece 41 is formed at the end.
is formed. Polyethylene terephthalate (PET) is used on the photoreceptor drum side of the paper conveyance guide 4.
A conveyance guide plate 5 made of an insulating elastic member such as . This conveyance guide plate 5 is glued along the paper conveyance guide 4, and its tip end is attached to a flat piece 41.
Similarly, a regulating portion 51 parallel to the photoreceptor drum 1 is formed. Furthermore, a protruding guide 52 is formed at the bent corner. Protruding guide 52
When pressed against stiff (thick) transfer paper, it bends. The distance between the protruding guide 52 and the photoreceptor drum 1 is approximately 1 mm, although it varies depending on the angle of the paper conveyance guide 4, the conveyance guide plate 5 (protrusion guide 52), etc. relative to the photoreceptor drum 1.

The transfer paper A is guided by the paper transport guide 4 and the transport guide plate 5 (projection guide 52) and is sent to the photoreceptor drum. Here, the point where the transfer paper A contacts the photoreceptor drum 1 is referred to as a contact point P. shall be. This contact point P will be described later, but it is almost the same whether the transfer paper has a strong stiffness or the transfer paper has a weak stiffness.
If the transfer paper A is charged before the contact point P (on the left side in the figure) in the rotational direction of the photosensitive drum, the phenomenon of toner flying onto the transfer paper does not occur. Therefore, a regulating portion 51 is formed on the side of the flat piece 41 facing the photosensitive drum 1. The regulating portion 51 prevents the corona ion flow from the charge line 3 from being irradiated after the contact point P (on the right side in the figure).

With the above configuration, when the transfer paper is thin and has a weak stiffness as shown in FIG. The photosensitive drum 1 rotates clockwise at approximately a contact point P. At this time, there is only a gap of approximately 1 mm between the photoreceptor drum 1 and the protruding guide 52, and even if there is paper with weak stiffness, the photoreceptor drum 1 will reach the contact point P.
come into contact with. In addition, when the transfer paper C is thick and has a strong stiffness as shown in FIG. Since the photosensitive drum 1 rotates clockwise, a clockwise force is applied to the transfer paper C. Since this transfer paper C has a strong stiffness, it presses the protrusion guide 52 clockwise to give it flex. As a result, the transfer paper C comes into contact with the photosensitive drum 1 at the contact point P and is conveyed clockwise. In this way, the contact point P can be applied to transfer paper with weak stiffness and transfer paper with strong stiffness.
can be brought into contact with the photoreceptor drum 1.

The corona ion flow generated by applying a high voltage to the charge line 3 is not irradiated beyond the contact point P where the transfer paper B or C contacts the photoreceptor drum 1 (on the right side in the figure). The toner on the surface of the photoreceptor drum 1 is not attracted by the transfer paper that is not adhered to the photoreceptor drum and flies to the transfer paper, and the toner does not scatter on the transfer paper.

In addition, the conveyance guide plate 5 (regulating plate 51) is made of PET.
Since the structure is made of insulating (elastic) members such as Therefore, the charge line-photosensitive drum current does not decrease and the transfer paper becomes difficult to be charged.

Furthermore, in this embodiment, in order to prevent the regulating portion 51 from coming too close to the charge line 3, the conveyance guide plate 5 is bonded to the photosensitive drum 1 side of the paper conveyance guide 4, so that the impedance of the charge line 3 becomes too high. Not at all.

In this embodiment, the regulating plate (regulating portion 51) is formed integrally with the conveyance guide plate 5, but may be formed separately.

(g) Effects of the Invention According to the present invention, even if the transfer paper has a strong stiffness, it contacts the photosensitive drum at the same contact point even if the transfer paper has a weak stiffness. Since the area charged by the transfer charger is regulated forward of this contact point with respect to the rotational direction of the photoreceptor drum, the transfer paper is unlikely to be charged before it contacts the photoreceptor drum. In other words, toner does not adhere to the transfer paper before the transfer paper contacts the photosensitive drum, and toner scattering does not occur in the formed image. In addition, since the tip of the paper conveyance guide extends approximately parallel to the surface of the photoreceptor drum in the direction of movement of the drum surface, the paper conveyance condition at the transfer position is extremely stable. Transfer defects caused by a sudden downward drop also do not occur.

In this way, a high-quality image without toner scattering can be obtained regardless of the stiffness of the transfer paper.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a transfer device according to an embodiment of the present invention, FIGS. 2A and B are diagrams showing the state in which transfer paper is fed by this transfer device, and FIG. 3 is a schematic diagram of a conventional transfer device. FIG. 3...Charge line, 4...Paper conveyance guide,
5... Conveyance guide plate, 51... (Corona ion flow) regulating section, 52... Projection guide.

Claims (1)

[Claims] 1. The leading end of the conductive paper conveyance guide that guides the transfer paper to the photosensitive drum surface is bent so that the leading end extends substantially parallel to the photosensitive drum surface along the direction of movement of the photosensitive drum surface, and , a regulating plate is provided that regulates the charging area by the transfer charger forward of the point where the transfer paper contacts the surface of the photoconductor drum with respect to the rotational direction of the photoconductor drum, and extends along the conveyance guide, and has a tip end facing the photoconductor drum. A protruding guide protruding toward the photoreceptor drum from a bent corner of the conveyance guide is provided to face the drum, the regulating plate and the protruding guide are made of an insulating member, and the protruding guide and the photoreceptor drum are connected to each other. A transfer device characterized in that the interval between the two is approximately 1 mm.