JPH0677170B2 - Transfer assist device for electronic copier - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer assisting device for an electronic copying machine, which eliminates the electric charge of a paper so that the transfer electric field does not reach the paper before entering the transfer process.

2. Description of the Related Art In a conventional electronic copying machine, a toner image formed on a photoconductor in a developing process is transferred onto a paper by bringing the paper into close contact with the photoconductor in a transfer process.

Problems to be Solved by the Invention When the transfer is carried out only in the region where the paper is completely adhered to the photosensitive member in the transfer step, a transferred image without disturbance of the toner image can be obtained. However, the transfer electric field generated from the transfer unit extends outside the transfer area where the paper is not in close contact with the photoconductor, so part of the toner image before the transfer process flies through the space between the photoconductor and the paper. Since it is transferred, clear image quality cannot be obtained. In particular, when a toner image is transferred onto a moist paper having a low electric resistance by using a transfer brush as the transfer means, the charge of the transfer brush is not limited to only the area of the paper in the transfer area, but just before the contact with the photoconductor. It also moves to the paper area and creates an unequal electric field between the paper and the photoreceptor. Due to this electric field, a part of the toner flies to the paper from the toner image formed on the surface of the photoconductor, and the obtained copy has toner b adhered in spots around the image a as shown in FIG. This is a cause of deterioration in image quality.

The present invention has been made for the purpose of improving the above problems.

Means and Actions for Solving Problems In order to achieve the above object, the present invention provides a toner image formed on the surface of a photoreceptor by a developing step,
In a transfer device of an electronic copying machine that transfers onto a sheet of paper in contact with a photoconductor in a transfer area, a position where a sheet of paper on which a toner image is transferred contacts the photoconductor and a transfer area of which the toner image on the photoconductor is transferred to the sheet of paper. A transfer auxiliary brush made of a conductive brush is installed between the start edge of the sheet to directly contact the paper that is in close contact with the photoconductor to eliminate static electricity from the paper. As a result, static elimination of the paper can be performed uniformly and efficiently.

An embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, 1 is a photoconductor of an electronic copying machine, 2 is a toner image formed on the surface of the photoconductor 1 by a developing process, and a paper transport roll 3
By the transfer brush that transfers to the sheet 4 sent by, the electric charge having the opposite polarity to the toner image is applied by the DC source 5. A transfer assist brush 6 and a sheet peeling brush 7 are provided before and after the transfer brush 2. These brushes 6,7
Both have a volume resistivity of 10 ^-2 to 10 ⁸ Ωcm and a thickness of 3 to 15 denier of conductive fibers 6a and 7a on base fabrics 6b and 7b treated with a conductive filler. The piles are flocked at a density of in ² , and the base cloths 6b and 7b are mounted on the support base 8 made of an insulating material, and the brushes 6 and 7
Both base fabrics 6b and 7b are grounded.

The transfer assist brush 6 is provided between a position B where the paper 4 carried into the transfer area A by the paper transport roll 3 contacts the surface of the photoconductor 1 and the start end of the transfer area A. Paper 4 touching the back side of paper 4 entering A
Of the toner image formed on the surface of the photoconductor 1 and a part of the toner flies toward the paper 4 before the paper 4 contacts the surface of the photoconductor 1. Can be prevented.

On the other hand, for the paper 4 that has been brought into close contact with the surface of the photoconductor 1 after the transfer process is completed, the electric charge charged on the paper 4 is removed by the paper peeling brush 7, so that the electrostatic coupling between the photoconductor 1 and the paper 4 is eliminated. After the release, the sheet 4 is peeled off from the surface of the photoconductor 1 and is sent to a fixing step (not shown) so that the toner image transferred onto the sheet 4 is fixed on the sheet 4.

FIG. 3 shows another embodiment in which the transfer assist brush 6, the transfer brush 2 and the sheet peeling brush 7 are arranged side by side on a support 8 made of an insulating material, and the brushes 5, 6, 7
Since they can be installed at the same time, assembly is easy.

FIG. 4 shows another embodiment in which the transfer corotron 9 is used as the transfer means, and the same effect as above can be obtained by removing the charge on the paper 4 immediately before the transfer step by the transfer auxiliary brush 6.

Further, FIG. 5 shows an embodiment in which the transfer auxiliary brush 7 is attached to the side surface of the shield case 9a of the transfer corotron 9.

EFFECTS OF THE INVENTION As described in detail above, the present invention is in close contact with the photoconductor between the position where the paper on which the toner image is transferred contacts the photoconductor and the start end of the transfer area for transferring the toner image on the photoconductor to the paper. A transfer auxiliary brush is provided which directly contacts the paper to neutralize the paper. Since the paper is brought into close contact with the photoconductor to neutralize the paper at a stable position, it is possible to uniformly and efficiently neutralize the paper.

As a result, even if you use paper that is moist and has low electric resistance, part of the toner does not fly from the surface of the photoconductor to the paper before the transfer process, so image bleeding and toner around the image may occur. It is possible to prevent deterioration of the image quality caused by the dot-shaped adhesion.

[Brief description of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a side view, FIG. 2 is a perspective view of a transfer assisting brush, and FIGS. 3, 4, and 5 are explanatory views showing other embodiments. FIG. 6 is an explanatory view showing a conventional defect. 1 is a photoconductor, 4 is a sheet, and A is a transfer area.

Claims (1)

[Claims] 1. A toner image is transferred in a transfer device of an electronic copying machine for transferring a toner image formed on the surface of a photoconductor 1 by a developing process onto a sheet 4 in contact with the photoconductor 1 in a transfer area A. Between the position where the paper 4 that contacts the photoconductor is in contact with the paper 4 that is in close contact with the photoconductor 1 between the beginning of the transfer area A that transfers the toner image on the photoconductor 1 to the paper 4
A transfer assisting device for an electronic copying machine, which is provided with a transfer assisting brush 6 made of a conductive brush that removes electricity.