JPS585767A - Transfer device - Google Patents

Abstract

PURPOSE:To prevent back staining of transfer materials and to make always good transfer possible by providing conductive members for guiding the transfer material to the surface of an image carrying body and grounding the transfer material through a constant voltage element. CONSTITUTION:A lower guide 4 and an upper guide 5 for guiding transfer paper 7 to the surface of a photosensitive drum 1 which is an image carrying body are provided. A varister 6 used as a constant voltage element is provided between the guide 4 and the ground. The varistor of, for example, 600V rating is provided as the constant voltage element. Always good transfer is performed by this without defective transfer under high humidity and back staining of images under constant low humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer device, and provides a good transfer device that does not cause transfer material backlash.

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus, developed images formed on an image carrier such as a photoreceptor are transferred onto a transfer material for use. For this transfer, guide s to guide the transfer material.
A transfer device that guides the material to the transfer position at I# and applies a corner discharge from the transfer abomasum is commonly used. In this type of transfer device, development occurred in places where partial transfer failure occurred at high temperatures and N transfer failure occurred.

The following techniques are known as countermeasures against this problem.

The first measure is to electrically float the transfer material guide.

If this method is used, even if the transfer member absorbs moisture at high temperatures, no transfer failure will occur. However, the transfer current flows into the transfer material guide and the transfer material guide becomes electrically charged, which attracts floating toner and synergy with the surface of the latent image carrier. This toner then comes into contact with the transfer member and causes stains on the image. In addition, when the humidity is low, friction between the transfer member and the transfer material guide causes charging and staining.

The countermeasure for ts2 is to apply a bias voltage to the transfer material guide guide.

At this time as well, transfer omissions are prevented as in the above system.

However, since a special power source is used, the device is grounded.

In order to prevent transfer failure during high humidity, the resistance of the transfer material guide should be selected so that the potential is higher than a predetermined potential.
If it is too high, it will cause staining of the transfer material guide.Furthermore, the suitable potential range is narrow, making Bontrok difficult.

The present invention has been developed in view of the above-mentioned points, and it is an object of the present invention to provide a transfer device that enables good transfer without transfer omissions.

The present invention provides a transfer image W in which developed images formed on a II carrier are transferred to a transfer material. and means for grounding.

The details of the present invention will be explained below by way of specific examples with reference to the drawings.
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FIG. 111 is a sectional view of a transfer device according to the present invention.

1 is a photosensitive drum, 2 is a developed film 13 is a transfer charger, 4 is a lower guide for guiding a transfer material, 5 is an upper guide for guiding a transfer material, and 7 is a transfer paper. 6 is a varistor used as a constant voltage element interposed between the guide and the ground. In a low humidity and normal temperature environment, the lower transfer material guide 4 is charged due to friction between the lower transfer material guide 4 and the transfer paper 7 . According to experiments, when the distance between the photosensitive drum 1 and the lower transfer guide 4 is 1.2 mm, the potential of the lower guide for guiding the transfer material reaches 1000 V or more. However, it has been found that when the voltage exceeds 700 V, thinner adheres to the leading edge, and the back 11 of the leading edge of the image on the next transfer paper becomes dirty. It was also confirmed that the lower the potential, the harder it is to get dirty. In addition, when the humidity is high, if the potential of the lower transfer material guide 4 is less than 450V, the corona current from the transfer charger 3 will flow into the lower transfer material guide 4 through the low resistance transfer paper 7, resulting in poor transfer. It has happened. The amount of current flowing at this time was 10 to 100 centimeters. From the above, in order to avoid stains and transfer defects in all environments, it is necessary to
It was found that when a current flows into the transfer material guide, the lower guide for the transfer material is kept at a voltage of 500 to 700 V, and when no current flows, such as when the humidity is low, the potential should be set as low as possible. In view of the experiment, 600
When using a v-rated varistor, there were no transfer defects at high humidity (we were also able to eliminate stains on the back of the image at normal low humidity).

Figure 2 is an example in which a Zener diode 8 is installed in place of the varistor of the constant voltage element shown in Figure 1. As a different matter, when 6 rows of Zener diodes with a rating of 100 V were connected, not only no transfer failure occurred in high humidity conditions, but also good transfer without back staining occurred even in low humidity conditions.

In the S-diagram, in each of the illustrated devices described above, only the lower transfer material guide is grounded through a constant voltage element, whereas the upper transfer material guide guide 51 is also grounded through a constant voltage element 6. . When a 600vyil Tsuru varistor was used as a constant voltage element, it was possible to prevent toner from adhering to the transfer material guide even if transfer was performed for a long time. Therefore, toner can be prevented from spilling onto the surface of the transfer material, and good transfer can be maintained.

[Brief explanation of the drawing]

Figure 111 is a cross-sectional view of a specific example transfer device based on the present invention, Figure 2 is a cross-sectional view of a modified example device based on the present invention, and Figure 115 is a cross-sectional view of a further modified example device based on the present invention. 1' photosensitive drum (image bearing member), 2' mortar developing toner,
3-transfer charger, 41 lower transfer material guide, 58 upper transfer material guide, 6I constant voltage element. Applicant Nakayanon Co., Ltd.

Claims (1)

[Claims] (1) A transfer device that transfers developed images formed on an image carrier to a transfer material, which includes a conductive transfer material guide member that guides the transfer material to the surface of the image carrier, and a grounding of the transfer material via a constant voltage element. A transfer device characterized by having means for.