Image forming apparatus capable of preventing the winding on the

Details Image forming apparatus capable of preventing the winding on the Image forming apparatus capable of preventing the winding on the

1992-11-24

1994-06-14

Moses, R. L.

Photocopying

Contact printing

Light boxes

355274, G03G 1516

Patent

active

053214773

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to an image-forming apparatus such as an electrophotographic duplicator and an electrophotographic printer utilizing the electrostatic transfer process, or more in particular to an image-forming apparatus constructed in such a manner as to prevent the contamination of a transfer member when transported by transfer member transport means and prevents drum trap from occurring when the transfer member passes a transfer point.


BACKGROUND ART

Conventionally, an apparatus using a transfer member transport belt as transfer member transfer means is well known as an image-forming apparatus of this type as shown in FIG. 1.
In FIG. 1, numeral 1 designates a photosensitive drum, numeral 2 a charger, numeral 3 an exposure device, numeral 4 a developer, numeral 5 a transfer charger, numeral 6 an erase lamp, numeral 7 a cleaner, numeral 8 a belt cleaner, numeral 9 a transfer member, numeral 10 a transfer member transport belt, and numerals 11, 12 a belt roller.
The photosensitive drum 1 has arranged therearound various parts including the charger 2, the exposure device 3, the developer 4, the transfer charger 5, the erase lamp 6 and the cleaner 7. The transfer member 9, which is transported by the transfer member transport belt 10, is supplied to a nip region where the photosensitive drum 1 is in contact with the transfer member transport belt 10.
This image-forming apparatus performs the operation described below.
First, the surface of the photosensitive drum 1 is uniformly charged by the charger 2, and is irradiated with light corresponding to the desired image to be formed at the exposure device 3 thereby to form an electrostatic latent image on the surface of the photosensitive drum 1. In the next step, toner is attached on the electrostatic latent image in the developer 4, so that a visible image is formed on the photosensitive drum 1. This visible image is moved to the nip region. The transfer member 9, on the other hand, is supplied from the direction A as indicated by arrow, and disposed on the transfer member transport belt 10 followed by being transported to the nip region by the transfer member transport belt 10. In the nip region, since the charge of a polarity opposite to that of the visible image is applied to the transfer member transport belt 10 from the transfer charger 5, the visible image on the photosensitive drum 1 is transferred onto the transfer member 9 in the nip region. The transfer member 9 with a visible image transferred onto the surface thereof, after being transported over a predetermined distance by the transfer member transport belt 10, is moved along the direction B as indicated by arrow separated from the transfer member transport belt 10, followed by an image being fixed on the surface of the transfer member 9 by means of a fixer (not shown).
The residual charges on the photosensitive drum 1 are erased by the erase lamp 6, and then the residual toner on the photosensitive drum 1 is removed by the cleaner 7 in preparation for a new image-forming cycle. The toner attached on the transfer member transport belt 10, on the other hand, is removed by the belt cleaner 8.
In the image-forming apparatus as mentioned above, by the way, the transfer member 9 that has passed a transfer point may usually be undesirably wound on the photosentive drum 1 due to various causes as a result of a phenomenon of what is called drum trap.
In the prior art, type, means for preventing drum trap is added. A typical one of such means is an eraser such as an AC corotron disposed at the boundary between the transfer member 9 and the transfer member transport belt 10 to enable the transfer member 9 to easily come off from the transfer member transport belt 10.
Further, as shown in FIG. 1, before transferring a visible image onto the transfer member 9, the transfer member transport belt 10 and the transfer member 9 thereon are charged into opposite polarities by a spare charger 14 and a conductive brush 15 conductively connected with the spare charger 14. As a result,

REFERENCES:
patent: 5153653 (1992-10-01), Fuma et al.
patent: 5191378 (1993-03-01), Itaya et al.

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