JPH0664406B2 - Transfer device - Google Patents

Description

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

(b) Conventional technology In an electrophotographic copying machine or the like, an electrostatic latent image is formed on the surface of a photoconductor drum, and frictionally charged toner is electrostatically adhered to the electrostatic latent image. A toner image is formed on the transfer paper by electrostatically transferring the toner onto the transfer paper whose back surface is charged by the corona ion flow. Figure 2 shows the process
FIG. 3 is a diagram showing a configuration of a transfer device that executes a process of transferring toner onto a transfer sheet. A charger box 2 is arranged so as to face the photoconductor drum 1. A charger wire 3 is stretched in the charger box 2. The charger box 2 and the charger wire 3 constitute a transfer charger. A high voltage is applied to the charger wire 3 to generate an orona ion flow. The transfer sheet is conveyed from the sheet conveying guide 4, and the back surface of the transfer sheet is charged by the corona ion flow as described above, so that the toner is transferred from the photosensitive drum 1 to the surface of the transfer sheet.

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

However, in the conventional transfer device as described above, the second
As shown in the figure, the back surface of the transfer sheet A is charged by the corona ion flow before the transfer sheet A contacts the surface of the photosensitive drum 1, and the charged area and the toner on the surface of the photosensitive drum 1 are charged. Coulomb force was generated between the and, and sometimes it flew to the charged area of the transfer paper. As a result, toner scatter appears in the image formed on the transfer sheet, resulting in a significant deterioration in image quality.

According to the present invention, the transfer paper is prevented from being charged before the transfer paper comes into contact with the surface of the photoconductor drum, thereby preventing the toner from scattering in the image formed on the transfer paper, thereby improving the image quality. The purpose is to improve.

(d) Means for Solving the Problems In the transfer device of the present invention, the leading end portion of the conductive paper transport guide that guides the transfer paper to the surface of the photoconductor drum is arranged so that the leading end portion is substantially parallel to the surface of the photoconductor drum. A charger box and a charger having a cross-sectional shape in which the transfer paper is bent so as to extend along the moving direction of the surface of the photoconductor drum and the transfer paper comes into contact with the surface of the photoconductor drum, and the side of the photoconductor drum and the conductive paper transport guide is open. A regulating plate that regulates the charging start position by the transfer charger consisting of lines and that makes the charging area by the transfer charger forward in the direction of rotation of the photosensitive drum from the point where the transfer paper contacts the surface of the photosensitive drum, The regulating plate is attached to the photosensitive drum side of the tip of the sheet conveying guide so as to project from the tip of the sheet conveying guide, and the regulation plate is made of an insulating member. Is characterized by.

(e) Action In this invention, the charging area of the transfer charger is regulated by the regulation plate provided on the sheet conveyance guide of the transfer sheet, and only the front side of the point where the transfer sheet contacts the surface of the photosensitive drum is charged. Like Therefore, the area of the transfer paper after the contact with the photoconductor drum is not charged, and the toner does not fly to the transfer paper. Further, since the regulation plate is made of an insulating member, a leak may occur between the charger wire and the regulation plate, or an excessive current may flow between the charger wire and the regulation plate to cause the charger wire-photosensitive drum. The current does not decrease and the transfer paper is not easily charged. Further, since the transfer charger starts charging from the point where the transfer sheet comes into contact with the surface of the photosensitive drum, the toner on the photosensitive drum and the transfer sheet come into close contact with each other from the time when the transfer sheet comes into contact with the photosensitive drum. As a result, a transfer error does not occur and a good transferred image can be obtained.

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

The photosensitive drum 1 is a cylindrical body having a photoconductive layer formed on the surface thereof, and is rotatable clockwise. A charger box 2 is arranged so as to face the photosensitive drum 1. The charger box 2 is made of a conductive material 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 transport guide 4. A charger wire 3 is stretched around the charger box 2 along the rotation axis of the photosensitive drum 1. This charger wire 4
A high voltage is applied to and a corona ion flow is generated. The charger box 2 and the charger wire 3 constitute a transfer charger.

Similarly to the charger box 2, the paper transport guide 4 is also made of a conductive member such as metal. The end portion of the sheet conveyance guide 4 is slightly bent so as to face the photoconductor drum, and forms a flat piece 41. The transfer sheet A is conveyed by being guided by the sheet conveying guide 4 so as to contact the photosensitive drum 1. The flat piece 41 is formed substantially parallel to the surface of the photosensitive drum 1 with a gap of 1.5 to 2.5 mm.
Not only does the transfer paper A guided by the paper transport guide 4 contact the photoconductor drum 1 to be in a good transport state along the photoconductor drum 1, but the rear end of the paper A is self-weighted. It is possible to prevent a sudden drop from the surface of the drum 1 by the above. Here, a point where the transfer sheet A is guided by the sheet conveying guide 4 and comes into contact with the photosensitive drum 1 is referred to as a contact point P. When the transfer sheet A is charged before the contact point P (on the left side in the drawing) with respect to the rotation direction of the photosensitive drum, the phenomenon of toner flying onto the transfer sheet does not occur. Therefore, the regulating plate 5 is arranged on the side of the flat piece 41 facing the photoconductor drum 1 so that the tip portion thereof projects from the tip portion of the flat piece 41. The regulation plate 5 is made of an insulating member such as polyethylene terephthalate (PET) and prevents the corona ion flow from the charger wire 3 from being irradiated after the contact point P (right side in the figure).

With the above-described configuration, the corona ion flow generated when the charger wire 3 is applied with a high voltage is generated after the contact point P at which the transfer sheet A contacts the photosensitive drum 1 (on the right side in the drawing). Since it is not irradiated, the photosensitive drum 1
Transfer paper that is not in contact with is not charged. Therefore, the toner on the surface of the photoconductor drum 1 is not attracted to the transfer paper that is not in contact with the photoconductor drum and does not jump to the transfer paper, and the toner is not scattered on the transfer paper.

In addition, since the transfer paper contacts the surface of the photosensitive drum,
Since the transfer charger starts charging, the toner on the photosensitive drum and the transfer sheet come into close contact with each other when the transfer sheet comes into contact with the photosensitive drum, and the transfer sheet and the toner on the photosensitive drum rub against each other. As a result, a good copy image can be obtained without causing transfer deviation.

Further, since the regulation plate 5 is made of an insulating member such as PET, leakage may occur between the charger wire 3 and the regulation plate 5, or an excessive current may flow between the charger wire and the regulation plate. The charger wire-photosensitive drum current does not decrease and the transfer paper is not easily charged.

Further, in the present embodiment, the regulating plate 5 is arranged on the side of the sheet conveying guide 4 on the photosensitive drum 1 so that the regulating plate 5 does not come too close to the charger wire 3 and the tip of the sheet conveying guide is not covered. Therefore, the impedance of the charger wire does not become too high. That is, if the regulation plate 5 is provided on the transfer charger side of the flat piece 41, since the regulation plate 5 is an insulating member, the discharge current flowing to the sheet conveyance guide is hindered. Therefore, the current to the photoconductor drum side increases correspondingly, and the influence of the charge unevenness due to the fluctuation of the applied voltage becomes more remarkable.

(g) Effect of the Invention According to the present invention, the charging plate regulates the charging area of the transfer sheet by the transfer plate provided on the sheet transport guide, and the transfer sheet is provided only in front of the contact point with the surface of the photosensitive drum. Get charged. Therefore, the area of the transfer paper after the contact with the photosensitive drum is not charged, the toner does not fly to the transfer paper, and the toner is scattered in the toner image formed on the transfer paper. Nothing.

In addition, since the transfer paper contacts the surface of the photosensitive drum,
Since the transfer sheet is charged and the transfer sheet comes into contact with the photosensitive drum, the toner on the photosensitive drum and the transfer sheet come into close contact with each other, so that transfer deviation does not occur and a good copy image is obtained. . Further, since the regulation plate is made of an insulating member, a leak may occur between the charger wire and the regulation plate, or an excessive current may flow between the charger wire and the regulation plate to cause the charger wire-photosensitive drum. The current does not decrease and the transfer paper is not easily charged.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a transfer device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a schematic configuration of a conventional transfer device. 3 ... Charger line, 4 ... Paper transport guide, 5 ... Regulation plate, P ... Contact point (between transfer paper and photoconductor drum).

Front page continuation (72) Inventor Yoshiharu Tsujimoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Masashi Hirai 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka (56) References JP 58-91479 (JP, A) JP 53-48529 (JP, A) JP 62-47082 (JP, A) JP 53-118136 (JP, A) 58-71758 (JP, U) JP49-16504 (JP, B1)

Claims (1)

[Claims] 1. A front end portion of a conductive paper transport guide for guiding a transfer sheet onto the surface of the photosensitive drum is folded so that the front end extends along the moving direction of the surface of the photosensitive drum substantially parallel to the surface of the photosensitive drum. Bending, at the point where the transfer paper comes into contact with the surface of the photosensitive drum, the charging start position by the transfer charger consisting of the charger box and the charger wire having a cross-sectional shape with the photosensitive drum and the conductive paper conveyance guide side open is regulated, In addition, a regulation plate that makes the charging area of the transfer charger forward with respect to the rotation direction of the photoconductor drum from the point where the transfer paper contacts the surface of the photoconductor drum is protruded from the tip of the paper transport guide. A transfer device, characterized in that the regulation plate is formed of an insulating member while being attached to the photoconductor drum side of the front end portion of the paper conveyance guide.