JPH0456882A - Transfer device for electrophotographic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a transfer device for an electrophotographic device.

Specifically, the present invention relates to a transfer device for an electrophotographic device such as a laser printer, a copying machine, and a facsimile machine.

l-Prior art J FIG. 6 shows the general configuration of a conventional electrophotographic apparatus.

In the figure, ■ is the main body of the apparatus, and inside the main body 1 of the apparatus there is an image carrier (for example, a photosensitive drum 2), a charging device 3, an optical system 4.
Developing device5. A fixing device 6, a transfer device 10, etc. are provided.

When printing using this electrophotographic device, the peripheral surface of the photosensitive drum 2 is uniformly charged (for example, −
650V). Then, a laser beam 4 is applied to the circumferential surface of the charged photosensitive drum 2 from an optical system 4 based on the print data.
A is irradiated. The toner in the developing device 5 is electrostatically adhered to the laser beam irradiation area. Here, a bias voltage (for example, -650V) is applied to the developing device 5, and the toner is charged (-650V).

Then, in the transfer device 10, the back surface of the transfer material P fed through the paper feed unit 7 is charged with a charge (positive charge) of the opposite polarity to that of the toner by utilizing a corona discharge phenomenon, thereby irradiating the laser beam. The toner image attached to the area is transferred from the photosensitive drum 2 to the surface of the transfer material P. Note that the transferred toner image is transferred to the transfer material P by the fixing device 6.
Fixed on top.

By the way, normally, the transfer device 10, as shown in FIG.
It is composed of a shield case 11, a discharge wire 12, and the like. A high voltage (for example, +5 kV) having a polarity opposite to that of the toner is applied to the discharge wire 12.

In addition, in FIG. 6, 13 is a paper kite.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned transfer device, a large amount of ozone is generated due to the corona discharge from the discharge wire 12, but since ozone has an adverse effect on the human body, there is a problem in the working environment. .

Therefore, roller-type transfer devices that can perform transfer operations without generating ozone have been put into practical use.

As shown in FIG. 5, this roller type transfer device presses an elastic roller 15 whose circumferential surface is made of conductive rubber or the like against the photosensitive drum 2.
Applying a high voltage of about ~' to 1 to 5, the roller 1 is
5 and the toner image on the photosensitive drum 2, the transfer material P is sent between the two (2, 15) due to the electrostatic attraction that acts between them.
A toner image is transferred thereon. However, in the roller type transfer device described above, since the elastic roller 15 is used by pressing it against the photosensitive drum 2, toner remaining on the photosensitive drum 2 adheres to the surface of the roller, and this adhered toner causes the transfer material to be transferred. There is an inconvenience that the back side of the paper may get dirty.

On the other hand, in order to expand the field of use of electrophotographic devices, there is a demand for miniaturization and cost reduction by simplifying the structure. Therefore, there is a strong need to simplify the structure of the transfer device as well.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an electrophotographic apparatus that can be miniaturized and cost-reduced, and that can perform transfer operations without generating ozone or staining the back surface of a transfer material. The purpose is to provide a transfer device.

[Means for Solving the Problems] The present invention provides a transfer device for an electrophotographic apparatus that transfers a toner image on an image carrier onto a transfer material, in which a back surface of the transfer material is provided on the upstream side of the image carrier. A power supply member that frictionally engages and frictionally charges the back surface is provided, and at least a portion of the power supply member that frictionally engages with the transfer material is configured to control the charging polarity of the toner image on the frictional charging series between the power supply member and the transfer material. It is characterized by being formed so that it is on the same polarity side.

[Function] In the present invention, when a toner image formed on an image carrier is transferred onto a transfer material, the back surface of the transfer material is frictionally engaged with the power supply member on the upstream side of the image carrier.

Here, the portion of the power feeding member that frictionally engages with the transfer material is formed to have the same polarity as the charging polarity of the toner image on the frictional charging series between the transfer material and the transfer material. The back surface is frictionally charged to have a polarity opposite to that of the toner image, and the toner image is transferred from the image carrier to the surface of the transfer material.

As described above, the transfer device according to the present invention actively utilizes the frictional electricity generated between the transfer material and the power supply member to charge the back surface of the transfer material to a polarity opposite to that of the toner image. As a result, miniaturization and cost reduction can be achieved. Further, since the back surface of the transfer material is charged without using the corona discharge phenomenon, no ozone is generated. moreover,
Since the power supply member is provided upstream of the image carrier and does not come into contact with the image carrier, it is not contaminated by toner or the like remaining on the image carrier. However, the back side of the transfer material is never contaminated by the power supply member.

Thereby, it is possible to reduce the size and cost, and moreover, it is possible to perform the transfer operation without generating ozone and without staining the back surface of the transfer material.

[Example 1 An embodiment of the present invention will be described based on the drawings.

The transfer device according to this embodiment is formed so that the back surface of the transfer material is charged to a polarity opposite to that of the toner image on the image carrier (photosensitive drum 2 in this embodiment) using triboelectricity.
As shown in the figure, it includes a power supply member (21).

Components that are the same as those shown in FIGS. 4 to 6 are denoted by the same reference numerals, and their explanations will be omitted or simplified.

Here, the power supply member is a means that is disposed upstream of the photosensitive drum 2 and frictionally engages with the back surface of the transfer material P to frictionally charge the back surface. At least the transfer material P of the power supply member
The portion that frictionally engages with the transfer material P is formed so as to have the same polarity as the charging polarity of the toner image on the photosensitive drum 2 on the frictional charging line between the transfer material P and the transfer material P.

In this embodiment, the power supply member is formed from the transfer brush 21.
Since the toner image a has negative polarity, it is formed so as to be on the negative polarity side in the frictional charging series between it and the transfer material P. More specifically, the brush portion 21a of the transfer brush 21 is made of polyester in which carphone is dispersed to give conductivity, and is flexible. Further, the transfer brush 21 is placed a predetermined distance upstream from the photosensitive drum 2 so as not to come into contact with the photosensitive drum 2! -1 distance apart.

The transfer device according to this embodiment uses a power supply device 31 to apply a bias voltage of opposite polarity to the toner (for example, 1
kV) is applied.

Next, the effect will be explained.

When transferring the toner image formed on the photosensitive drum 2 onto the transfer material P, the back surface of the transfer material P is frictionally engaged with the transfer brush 21 on the upstream side of the photosensitive drum 2. Here, the transfer brush 21 is formed to have the same polarity as the charging polarity of the toner image (that is, on the negative polarity side) on the frictional charging series between the transfer brush 21 and the transfer material P, so that the back surface of the transfer material P is The toner image is transferred from the photosensitive drum 2 onto the surface of the transfer material 9 by being charged S (positively charged) with a polarity opposite to that of the image. At this time, since a bias voltage (lk) having a polarity opposite to that of the toner image is applied to the transfer brush 21 using the power supply device 31, further improvement in transfer performance is guaranteed.

In this way, since the I:i friction generated between the back surface of the transfer material P and the transfer brush 21 is actively used to charge the back surface of the transfer material P to the opposite polarity to that of the toner image, the structure is simplified. be done. Furthermore, since the corona discharge phenomenon is not used during transfer, no ozone is generated.Furthermore, since the transfer brush 21 is provided upstream of the photosensitive drum 2 and does not come into contact with the photosensitive drum 2, no ozone remains on the photosensitive drum 2. It will not be contaminated by toner etc. Therefore, the back surface of the transfer material P is not soiled by the transfer brush 21.

According to this embodiment, the upstream side of the photosensitive drum 2 is frictionally engaged with the back surface of the transfer material P, and the back surface is l:l!
A power feeding member (transfer brush 21) for frictional charging is provided, and at least a portion of the power feeding member that frictionally engages with the transfer material P is placed on the frictional charging line between the photosensitive drum 2 and the transfer material P.
Since the toner image is formed to have the same charging polarity as the toner image above, it is possible to reduce the size and cost.Moreover, the transfer operation can be performed without generating ozone or staining the back side of the transfer material P. can be done.

Further, since the power supply member does not come into contact with the photosensitive drum 2 and is not contaminated by toner remaining on the drum 2, there is no need to provide a special cleaning device. Cost reduction can be easily achieved.

Furthermore, since the power supply member is composed of the transfer brush 21,
The power feeding member can be brought into surface contact with the back surface of the transfer material P so that the contact area is increased, and the back surface of the transfer material P can be charged uniformly and reliably. Therefore, transfer performance can be improved. In particular, in this embodiment, the power supply device 31 is used to connect the power supply member (transfer brush 21
) is applied with a bias voltage of opposite polarity to the toner (for example, 1 kV), so the transfer performance can be further improved. Furthermore, even when using the power supply device 31, there is no need to increase the bias voltage. Miniaturization and cost reduction can be easily achieved.

Furthermore, since the transfer brush 21 is flexible, it can be brought into contact with the transfer material P without strict positioning during assembly. Therefore, assembly becomes easy.

In the above embodiment, the power supply member is connected to the transfer brush 2.
1, or may be constructed in any manner as long as it frictionally engages with the back surface of the transfer material P to frictionally charge the back surface.6 For example, the power feeding member may be a rotating brush as shown in FIG. 2
It may be composed of 5. Specifically, the rotating brush 25 includes a rotatably provided shaft 26 and a conductive and flexible brush 27 provided on the circumferential surface of the shaft 26. This brush 27 is formed so as to have the same polarity as the band S polarity of the toner image on the photosensitive drum 2 on the frictional charging line between the brush 27 and the transfer material P.

In a transfer device equipped with such a rotating brush 25, the back surface of the transfer material P on the upstream side of the photosensitive drum 2 is
5 and is positively charged by friction, and a toner image is transferred from the photosensitive drum 2 onto the surface of the transfer material 1. At this time, if the rotating brush 25 is actively rotated using a driving means, the back surface of the transfer material P can be more effectively charged by friction.

In addition, at least the portion of the power supply member that frictionally engages with the transfer material P (brush 21a of the transfer brush 21, brush 27 of the rotating brush 25) is made of a material in which carbon is dispersed in polyester to give conductivity, or the transfer material It may be formed in any manner as long as it has the same polarity as the charging polarity of the toner image on the photosensitive drum 2 on the frictional charging series between the toner image and the photosensitive drum 2.

Furthermore, the photosensitive drum 2 may be selected as the image carrier, or it may be of any type as long as it can form a toner image based on an electrostatic latent image.

[Effects of the Invention] According to the present invention, a power supply member is provided on the upstream side of the image carrier to frictionally engage with the back surface of the transfer material to charge the back surface by I:iI friction, and the power supply member is provided at least for transfer. Since the part that frictionally engages with the transfer material is formed so that it has the same polarity as the toner image charging polarity on the frictional charging series between the transfer material and the transfer material,
The size and cost can be reduced, and the transfer operation can be performed without generating ozone or staining the back surface of the transfer material.

25...Rotating brush (power supply member).

Claims (1)

[Claims] (1) In a transfer device of an electrophotographic apparatus that transfers a toner image on an image carrier onto a transfer material, a device is provided on the upstream side of the image carrier that frictionally engages with the back surface of the transfer material to triboelectrically charge the back surface. a power supply member is provided, and at least a portion of the power supply member that frictionally engages with the transfer material is formed to have the same polarity as the charging polarity of the toner image on a frictional charging series between the power supply member and the transfer material. A transfer device for an electrophotographic device, characterized in that: