JPH0433029B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic apparatus used as a copying machine or a printer.

Conventionally, in an electrophotographic apparatus, six processes of charging, exposure, development, transfer, cleaning, and neutralization are performed on a photosensitive drum or a coated photosensitive drum that rotates at a constant speed.

Among these processes, the transfer process has problems such as deterioration of image quality and saturation of transfer efficiency at a low rate, which becomes particularly noticeable when using magnetic toners that have been developed in recent years. In other words, in the transfer process, the toner on the photosensitive drum is electrostatically attracted from the back side of the transfer material such as plain paper using corona ions or an electric field roller, but if the electric field is too strong, the toner will scatter, deteriorating the transferred image, and vice versa. The disadvantage is that the transfer efficiency is low.

The present invention has been made to solve these drawbacks, and aims to prevent image deterioration during transfer and improve transfer efficiency. The photosensitive drum is stretched so that it is in close contact with about half the circumference of the photosensitive drum while the other parts are separated and rotated by friction with the photosensitive drum. After forming an electrostatic latent image on the photosensitive drum, the photosensitive drum is Development is performed at the position where the drum and dielectric belt are in close contact, and the toner is attracted and adhered to the dielectric belt, and at the position where the photosensitive drum and dielectric belt are separated, the toner on the dielectric belt is transferred to paper, etc. It is characterized by being able to be transferred onto materials.

To explain the following with reference to the drawings, FIG. 1 is a side view showing one embodiment of the present invention, and in the figure 1 is an arrow a.
It is a photosensitive drum that rotates at a constant speed in the direction of the photosensitive drum, and has a structure in which the surface of a conductive base material such as aluminum is coated with a photo-semiconductor such as Se or CdS.

A dielectric belt 2 is made of a transparent polyester film or the like with a thickness of about 10 μm to 200 μm, and is formed into an endless shape, and has a width approximately equal to the length of the photosensitive drum 1 in the axial direction. This dielectric belt 2 is wrapped around the photosensitive drum 1 and rollers 3a, 3b, etc. arranged near the photosensitive drum 1, so that a part of the dielectric belt 2 tightly covers about half the circumference of the photosensitive drum 1, and the other part is separated from the photosensitive drum 1. The photosensitive drum 1 is suspended to maintain an appropriate tension, and when the photosensitive drum 1 rotates in the direction of arrow a, it rotates at the same speed due to friction.

4 is a charging device such as a corona discharger, 5 is an exposure optical system, 6 is a developing device, 7 is a toner, 8 is a transfer material such as plain paper, 9 is a transfer device such as a corona discharger or an electric field roller, and 10 is a transfer device such as a corona discharger or an electric field roller. A light source for static elimination, 11 is a cleaning unit, in which the charger 4 and the light source for static elimination 1 are connected to each other.
0 is disposed between the photosensitive drum 1 and the dielectric belt 2, and the exposure optical system 5 and the developing device 6 are disposed so as to face the surface of the dielectric belt 2 that is in close contact with the photosensitive drum 1. ing. and transfer device 9
is arranged so as to face the surface of the dielectric belt 2 at a position where the photosensitive drum 1 and the dielectric belt 2 are separated, and the cleaning unit 11 is arranged to face the surface of the dielectric belt 2 at a position where the photosensitive drum 1 and the dielectric belt 2 are separated.
It is provided so as to contact the surface of the dielectric belt 2 at a position between a and 3b.

12 is a conveyor belt for conveying the transfer material 8 in the direction of arrow b, and 13 is a fixing device disposed at one end of the conveyor belt 12.

Next, we will explain the operation of the above configuration.
First, the photosensitive drum 1 rotates at a constant speed in the direction of arrow a.
After being uniformly charged by the charger 4, an electrostatic latent image is formed by the exposure optical system 5. At this time, fog light is generated through a transparent dielectric belt 2, and an electrostatic latent image is formed on the photosensitive drum 1. Since the dielectric belt 2 allows electric lines of force to pass through it, when development is performed by the developing device 6 in the next step, the toner 7 holding the charge is attracted to the electrostatic latent image via the dielectric belt 2, and the toner 7 is attracted to the electrostatic latent image through the dielectric belt 2. Deposit on dielectric belt. However, in the case of reversal development, the polarity of the charge held by the toner 7 is different from that described above, and the toner 7 is electrostatically attracted to the charge generated on the conductive base material of the photosensitive drum 1.

In this way, the toner 7 deposited on the dielectric belt 2 is sent to the transfer position as shown in FIG. The back surface of the transferred transfer material 8 receives electrostatic attraction due to an electric field or charge by the transfer device 9. Note that the electric field and charge from the transfer device 9 at this time have a polarity different from the charge held by the toner 7. Since the dielectric belt 2 separates from the photosensitive drum 1 at the same time as the electrostatic attraction by the transfer device 9, the force with which the toner 7 is attracted to the photosensitive drum 1 via the dielectric belt 2 weakens, and the toner 7
adheres to the transfer material 8. At this time, dielectric belt 2
Since the transfer material 8 and the transfer material 8 are mechanically in close contact with each other, the suction force for transfer remains unchanged, and scattering of the toner 7 is suppressed. After the transfer is completed, the transfer material 8 is peeled off from the dielectric belt 2 and transferred onto the conveyor belt 12, and is sent in the direction of arrow b by the conveyor belt 12, but the attraction force between the transfer material 8 and the dielectric belt 2 is weak. Furthermore, since the transfer material 8 is electrostatically attracted to the conveyor belt 12, peeling is performed reliably, and since the toner 7 is also electrostatically attracted and adhered to the transfer material 8, the toner remaining on the dielectric belt 2 is removed. 7 is small. Therefore, high transfer efficiency can be obtained.

The transfer material 8 is sent in the direction of arrow b by the conveyor belt 12, and after the toner 7 is fixed by the fixing device 13, it is output.

On the other hand, the photosensitive drum 1 separated from the dielectric belt 2
receives static eliminating light from the static eliminating light source 10 and is neutralized. Further, after the transfer material 8 is peeled off, the dielectric belt 2
The cleaning unit 11 removes residual toner.

The exposure optical system uses a recently developed LED array,
Alternatively, if a laser scanning device is used, it is compact and can be placed between the photosensitive drum and the dielectric belt. In this case, the electrostatic latent image can be directly formed on the photosensitive drum, so the dielectric belt is It can be used even if it is opaque.

As explained above, the present invention involves sucking and adhering toner to a dielectric belt that is brought into close contact with a photosensitive drum.
During transfer, the toner on the dielectric belt is sucked from the back side of the transfer material, and at the same time the dielectric belt and photosensitive drum are separated. As a result, even when using magnetic toner, high transfer efficiency and high image quality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of an electrophotographic apparatus according to the present invention, and FIG. 2 is an enlarged sectional view of the vicinity of the transfer position in FIG. 1...Photosensitive drum, 2...Dielectric belt, 3
a, 3b...Roller, 4...Charger, 5...Exposure optical system, 6...Developer, 7...Toner, 8...
Transfer material, 9...transfer device.

Claims (1)

[Scope of Claims] 1. A photosensitive drum and a blank stretched around half the circumference of the photosensitive drum so that a part of the photosensitive drum is adsorbed and the other part is separated from the photosensitive drum and rotates due to friction with the photosensitive drum. A belt-shaped dielectric belt, an exposure optical system, a developing device, and a transfer device are provided, and an electrostatic latent image is formed on the photosensitive drum by the exposure optical system, and the photosensitive drum and the dielectric belt are brought into close contact with each other. At the position where the photosensitive drum and the dielectric belt are separated, a developing device performs development to adhere the toner onto the dielectric belt, and at a position where the photosensitive drum and the dielectric belt are separated, a transfer device transfers the toner on the dielectric belt to a transfer material. electrophotographic equipment.