JPH073615B2 - Corona transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona transfer device such as an electrophotographic copying machine.

2. Description of the Related Art In recent years, a corona transfer device, which develops a toner image on an image bearing member such as a photoconductor to form a toner image and transfers the toner image onto a transfer material by a transfer charger, is most commonly used in recent years. ing.

An example of the above-described conventional corona transfer device will be described below with reference to the drawings.

FIG. 2 shows a conventional corona transfer device. Second
In the figure, a toner image 2 developed on an image carrier 1 such as a photosensitive drum is provided on a transfer material (paper) 3 sent along a transfer material guide plate 4, a shield 5 and a discharge wire 6 are provided. And is transferred by the transfer charger 7.

Problems to be Solved by the Invention However, in the above-described configuration, the toner image on the image carrier 1 may be dispersed on the transfer material 3 due to transfer, and the image quality may deteriorate. For example, the original characters shown in FIG. 3A are deteriorated by the transfer as shown in FIG. 3B.

The above cause is that the contact width between the transfer material and the image carrier (along the traveling direction of the transfer material) cannot be sufficiently secured. That is, in FIG. 2, since the transfer material is subjected to corona discharge in a state where the transfer material is not yet in close contact with the image carrier, the toner is scattered during the transfer, which causes the toner to be scattered around the characters as shown in FIG. 3b. In some cases, the line itself disappeared in the case of fine letters.

In order to prevent such corona spread, there is an attempt to limit the transfer material entrance side opening where the opening of the transfer charger is narrowed as shown in FIG. 4, but in this case, toner scattering during transfer does not occur. Although this can be prevented, the transfer efficiency decreases because the corona current that flows through the shield increases, and the electrostatic attraction force between the transfer material and the image carrier becomes insufficient, causing a slight deviation between the transfer material and the image carrier, so-called jitter. Is likely to occur. In addition, since the opening is narrow, it is difficult to clean the transfer charger when it becomes dirty.

In view of the above problems, the present invention provides a corona transfer device that has high image quality and is easy to maintain.

Means for Solving the Problems In order to solve the above problems, the corona transfer device of the present invention has a substantially U-shape in which a corona discharge wire is extended and one side is an opening and three directions are surrounded by a conductive member. Of the shield case, a transfer charger in which insulating members are attached to the inner walls on both sides sandwiching the corona discharge wire so as to protrude from the side wall of the shield case, an image carrier on which a toner image is formed, and this image carrier and the transfer An image carrier side is provided with a conductive member between the charging device and a transfer material guide plate having a transfer charging device side made of an insulating member. The insulating member of the transfer material guide plate protrudes from the conductive member to transfer charging. The container is arranged so as to cover the transfer material entrance side opening of the container.

The present invention has the above-described configuration, and since the corona discharge from the corona discharge wire is strongly focused on the contact area between the image carrier and the transfer material, the toner scattering is small, the transfer efficiency is good, and the high-quality image with less jitter is obtained. In addition, cleaning is easy and maintainability is high. Furthermore, a stable transfer image is obtained which is resistant to dirt.

Embodiment A corona transfer device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a corona transfer device in one embodiment of the present invention. In FIG. 1, 11 is an image bearing member such as a photosensitive drum, which rotates in the direction of the arrow and the toner image 12 developed on the image bearing member reaches the transfer position. 13 is a transfer material such as paper. Corona Transfer Device is Corona Discharge Wire 16
And a shield case 17 made of a conductive material such as metal surrounding it.
And a transfer charger 101 having insulating members 18 and 19 such as polyester films attached to the inner surfaces of both side walls of the shield case 17, a conductive member 14 such as a metal on the image carrier side, and a polyester on the transfer charger side. The transfer material guide 102 includes an insulating member 15 such as a film. Transfer material guide 102
Is disposed at an appropriate space position between the inner wall of the transfer advancing side insulating member 18 of the transfer charger 101 and directly above the corona discharge wire 16. Further, the insulating member 18 on the inner wall of the transfer charger 101,
The height of 19 is higher than that of each side wall of the shield case 17, and the insulating member 15 of the transfer material guide 102 is slightly projected from the conductive member 14.

The operation of the corona transfer device configured as described above will be described with reference to FIG.

A state of corona discharge when a transfer compaction is applied to the corona discharge wire 16 from a high voltage power source is schematically shown by lines of electric force 20 and 21. Since the transfer charger 101 is provided with the insulating members 18 and 19 on the inner surfaces of both side walls of the shield case 17, corona discharge is applied to the bottom surface of the shield case 17 which acts as a flow of 20 toward the transfer material 13 and a back electrode. Divided into 21 flows on the other side, there is no wasteful flow to the side. Further, since the transfer material entrance side opening of the transfer charger 102 is covered with the insulating member 15 of the transfer material guide 102, a corona discharge current strongly directed to the contact area of the transfer material 13 can be efficiently obtained.

Further, due to the presence of the conductive member 14 of the transfer material guide 102,
Inconvenience that electric charges that are likely to be accumulated on the upper surface of the insulating member 15 are released, and floating toner is adsorbed when the electric charges are accumulated on the upper surface of the insulating member 15, and this toner adheres to the back surface of the transfer material 13 to cause back stain. Alternatively, it is possible to effectively prevent a sub-effect on the transfer due to the attached toner.

The insulating members 15, 18, 19 are conductive members 14, 18, respectively.
If the tip is the same as or shorter than the shield case 17, the floating toner accumulated on the tip may cause high-pressure leak under high humidity conditions and transfer may not be possible, or in the worst case the device may be damaged. In the embodiment, the insulating members 15, 18,
Since 19 respectively projects from the conductive member 14 and the shield case 17, even if they are contaminated by the floating toner from the developing device, they do not leak, and good transfer is always possible under all environments.

As described above, according to this embodiment, since the corona discharge is strongly and effectively applied to the contact area between the image carrier and the transfer material, the toner scattering is small, the transfer efficiency is good, and the high quality image with less jitter can be obtained. . Further, since the transfer charger does not limit the opening, it can be easily cleaned when it becomes dirty. Further, even under high humidity, no leak occurs and stable transfer is possible.

EFFECTS OF THE INVENTION As described above, according to the present invention, the corona discharge wires are stretched, one side is an opening, and three directions are surrounded by conductive members. A transfer charger in which an insulating member is attached so as to protrude from the side wall of the shield case, an image carrier on which a toner image is formed,
A transfer material guide plate having a conductive member on the image carrier side and an insulating member on the transfer charger side is provided between the image carrier and the transfer charger, and the insulating member of the transfer material guide plate is a conductive member. By arranging so as to project more than that and cover the opening on the transfer material entrance side of the transfer charger, high quality image quality with less toner scattering, high transfer efficiency and little jitter, and stable environmental maintenance It is possible to provide an easy corona transfer device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a corona transfer device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional example, and FIG. 3 is an original character to be copied and deterioration due to transfer. FIG. 4 is a diagram showing an example of characters, and FIG. 4 is a configuration diagram of another conventional example. 11 ... Image carrier, 12 ... Toner image, 13 ... Transfer material, 101
...... Transfer charger, 102 …… Transfer material guide plate.

Claims (1)

[Claims] 1. A corona discharge wire is stretched, and an insulating member is shielded on the inner walls on both sides of the corona discharge wire of a substantially U-shaped shield case in which one side is an opening and three directions are surrounded by conductive members. A transfer charger attached so as to protrude from the side wall of the case, an image carrier on which a toner image is formed, and a conductive member on the image carrier side and a transfer charger between the image carrier and the transfer charger. A transfer material guide plate whose side is an insulating member, and the insulating member of the transfer material guide plate is arranged so as to protrude beyond the conductive member and cover the transfer material entrance side opening of the transfer charger. Corona transfer device characterized by.