JPH1124445A - Transfer device - Google Patents

Abstract

(57) [Problem] To provide a transfer device capable of improving transferability in a thin line portion and realizing high resolution and high print quality. A transfer device (5a) has at least two corotron wires and each corotron wire
(6, 7) is separated by a shield member (5c), the voltage applied to the corotron wire is weak at the corotron wire (6) on the paper entrance side, and the corotron wire (7) on the paper exit side
Was set to an applied voltage at which the transfer efficiency was maximized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device.

[0002]

2. Description of the Related Art FIG. 3 shows a schematic configuration diagram of a transfer device of a conventional electrophotographic apparatus. As shown in FIG.
a is formed by a retractor blade 8 that presses the paper 11 against the photoreceptor 1 and a transfer device 5b that applies a high voltage having a polarity opposite to that of the toner 9 to the corotron wire 6 to generate a corona having a polarity opposite to that of the toner 9. . FIG. 4 is a conceptual diagram of the photoconductor and toner potential behavior by the transfer device of the electrophotographic apparatus of FIG.
Shown in An electrostatic latent image is formed on the photoconductor 1 by charging and exposure as an electrophotographic process, and is developed as a toner image by the developing device 4. The toner image is a reversal development, and is held and adsorbed on the surface of the photoconductor 1 by a potential difference between an exposed portion and a non-exposed portion.

The toner image on the photoreceptor 1 is pressed against the sheet 11 by a retractor blade 8, and is electrostatically transferred to the sheet 11 by a corona having a polarity opposite to that of the toner 9 generated by the transfer unit 5b.

According to the above-mentioned prior art, since the potential difference between the exposed portion and the non-exposed portion is high and the toner image is electrostatically attracted to the photoreceptor 1, the transferability of fine lines is low, and a high resolution pattern is obtained. There was a problem that it was difficult to come out.

Next, FIG. 5 shows an example in which a static elimination lamp 12 is arranged in front of the transfer device 5a in order to weaken the electrostatic attraction between the photosensitive member 1 and the toner 9. FIG. 6 is a conceptual diagram of the photoconductor and toner potential behavior by the transfer device of the electrophotographic apparatus of FIG. According to this configuration, the potential of the photoconductor in the non-exposed portion can be removed to the residual potential of the photoconductor 1 before the transfer, so that the attraction of the toner 9 to the photoconductor 1 is reduced, and the transferability of fine lines is improved. There is an advantage. However, the non-exposed portions, that is, the toners 9 of the same polarity that have been pushed in by the potential difference between the exposed portion and the non-exposed portion in order to neutralize the toner image peripheral portion repel each other due to the disappearance of the potential difference wall, The problem of splattering around occurs.

In order to solve the above-mentioned problems, it is necessary to limit the amount of exposure of the static elimination lamp 12 in front of the transfer device 5a. Accordingly, dustproof means and periodic cleaning are required, which makes it difficult to ensure reliability. In addition, there is a problem that the cost is high.

[0007]

In the transfer device of the prior art, there was a problem that the transferability of the thin line portion was poor and the image reproducibility of the thin line portion was low. Further, even in the configuration using the static elimination exposure device before the transfer device, the print quality is reduced due to the scattering of the toner, and there is a problem that the reliability is low.

An object of the present invention is to provide a transfer device capable of improving transferability at a thin line portion and realizing high resolution and high print quality.

[0009]

An object of the present invention is to provide a transfer apparatus for transferring a toner image formed on a photoreceptor to paper by applying a voltage having a polarity opposite to that of toner to a corotron wire. At least two or more corotron wires are provided, and each corotron wire is provided with a shield member between the corotron wires. The voltage applied to the corotron wire is weak at the corotron wire on the paper entrance side, and the corotron wire on the paper exit side is reduced. Is achieved by setting the applied voltage to maximize the transfer efficiency.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration diagram of an embodiment according to the present invention. Around the photoconductor 1, a charger 2, an exposure device 3, a developing device 4, and a transfer device 5a are arranged. The transfer device 5a includes a retractor blade 8 for pressing the sheet 11 against the photoreceptor 1, two corotron wires 6, 7 for generating a corona having a polarity opposite to that of the toner 9, and a shield member 5c for separating the corotron wires. It is constituted by a vessel 5b. It is generally known that the transfer efficiency has a maximum value with respect to the electric field strength (applied voltage), but in the corotron wire of the transfer device 5b, the applied voltage of the corotron wire 6 at the entrance of the transfer device 5b is The transfer efficiency is set to 50% or less, a value weak enough to transfer about half of the toner image on the photosensitive member. Further, the voltage applied to the corotron wire 7 at the exit of the transfer device 5b is set to an applied voltage that maximizes the transfer efficiency.

FIG. 2 is a conceptual diagram showing the potential behavior and charging behavior of the photosensitive member 1 and the toner 9 in the transfer device 5a of the present invention. Photoreceptor 1 by electrification and exposure as an electrophotographic process
An electrostatic latent image is formed thereon, and the electrostatic latent image is developed by the developing device 4 to form a toner image held on the surface of the photoconductor 1 by a potential difference between an exposed portion and a non-exposed portion on the photoconductor 1. I do.
The toner image is transferred to the paper 11 by about half the layer by the corotron wire 6 on the entrance side of the transfer unit 5b. At this time, the potential difference between the exposed portion and the non-exposed portion is reduced, and the toner image remaining on the photoreceptor 1 without being transferred is held without scattering. Further, the toner 10 in the upper layer of the toner image remaining on the photoreceptor 1 is charged to the opposite polarity. Next, the transfer device 5b
Most of the residual toner image on the photoconductor 1 is transferred to the paper 11 by the exit corotron wire 7. At this time, as described above, since the toner 10 in the upper layer of the residual toner is charged to the opposite polarity, that is, the same polarity as the paper 11, no scattering occurs.

As described above, by performing the transfer process stepwise, the transferability of fine lines is improved, and the occurrence of toner scattering due to transfer is eliminated, and high print quality with high resolution is obtained.

[0013]

As described above, according to the present invention, the transfer process is performed stepwise to improve the transferability of fine lines, eliminate toner scattering due to transfer, and realize high resolution and high print quality. It is possible to provide a transfer device capable of performing the transfer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a transfer device of the present invention.

FIG. 2 is a conceptual diagram of a photoconductor and toner potential behavior by the transfer device of the present invention.

FIG. 3 is a schematic configuration diagram of a conventional technique.

FIG. 4 is a conceptual diagram of a photoconductor and toner potential behavior by the transfer device of FIG. 3;

FIG. 5 is a schematic configuration diagram of another conventional technique.

FIG. 6 is a conceptual diagram of a photoconductor and toner potential behavior by the transfer device of FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor, 2 ... Charger, 3 ... Exposure device, 4 ... Development device, 5a ... Transfer device, 5b ... Transfer device, 6, 7 ... Corotron wire, 8 ... Retractor blade, 9 ... Toner, 10
... toner charged to reverse polarity, 11 ... paper, 12 ... static elimination lamp.

Claims (1)

[Claims] 1. A transfer device for applying a voltage having a polarity opposite to that of toner to a corotron wire to transfer a toner image formed on a photoreceptor to paper, wherein the transfer device has at least two corotron wires. At the same time, each corotron wire is separated by a shield member, and the voltage applied to the corotron wire is weakened at the corotron wire at the paper entrance side and maximized at the transfer efficiency at the corotron wire at the paper exit side. A transfer device, wherein the transfer device is set to a voltage.