JPH06282179A - Transfer device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a hollow character in a transfer device that transfers a toner image, formed on the surface of a photoreceptor after a latent image formation process and a development process, to transfer paper in a transfer part. CONSTITUTION:The device is provided with a transfer paper carry means which carries a cut sheet of transfer paper 6 to the photoreceptor 1; and a roller 15 which makes the transfer paper 6 adhere to the photoreceptor 1 and, at the same time, applies an electric field for transferring a toner image to the transfer paper 6. The transfer paper carrying means differs from the photoreceptor 1 in speed. Thereby, the occurrence of a hollow character is surely prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device, and more particularly to a transfer device for transferring a toner image onto a recording sheet such as an electrophotographic copying machine and various printers.

[0002]

2. Description of the Related Art Generally, as an apparatus for transferring a toner image onto a transfer sheet by bringing the toner image on a toner image support into contact with the transfer sheet, a so-called corona transfer is applied to the back surface of the transfer sheet by corona discharge. There are known methods, such as a method in which a roll, a drum, a belt, etc. are brought into contact with the back surface of the transfer paper and a high potential is applied to the roll, the drum, the belt, etc. to perform the transfer.

[0003]

As a drawback often seen in the above-mentioned conventional transfer system, as shown in FIG. 3 (a), the intermediate portion b of the character image a and the defect shown in FIG. 3 (b). In addition, a phenomenon (hereinafter referred to as a hollow character) that partially appears but is not collectively transferred is generated near the edge portion d of the large area image c. It is an object of the present invention to provide a transfer device that does not cause the hollow character as described above.

[0004]

The present invention provides a transfer device for transferring a toner image formed on a surface of a toner image support through a latent image forming step and a developing step onto a transfer paper at a transfer portion. A transfer sheet conveying unit that conveys a transfer sheet composed of a cut sheet to the image support, and a roller that applies an electric field to bring the transfer sheet into close contact with the toner image support and at the same time transfer the toner image to the transfer sheet are provided. Then, the transfer paper conveying means has a speed difference with respect to the toner image support.

[0005]

According to the present invention, in a transfer device, a transfer paper conveying unit that conveys a transfer paper made of cut paper to a toner image support, and the transfer paper is brought into close contact with the toner image support, and at the same time the toner image is Since the transfer sheet conveying means has a roller for applying an electric field for transferring to the transfer sheet and the transfer sheet conveying means has a speed difference with respect to the toner image support, generation of a hollow character is prevented.

[0006]

[Examples] FIG. 1 is a schematic view showing an example of the process of an electrophotographic copying machine, in which a photoreceptor 1 which is a toner image support.
Are charged by the charger 2 and exposed by the exposure unit 3 to form an electrostatic latent image on the photoconductor 1. The electrostatic latent image on the photoconductor 1 is visualized by the toner in the developing unit 4, and the visualized toner image is transferred by the transfer paper 6 and the transfer unit 7 which are cut sheets sent from the paper feeding unit 5. The transfer paper 6 is contacted and transferred to the transfer paper 6 by an electric field. The transfer paper 6 is then sent to the fixing unit 8 and the toner image is fixed on the transfer paper 6. In addition, 9 is a cleaning part.

FIG. 2 shows a transfer sheet conveying means in the transfer section 7, which is a roll 1 as the transfer sheet conveying means.
An endless belt 11 is wound around 0 and 10, and the transfer paper carry-in side of the belt 11 is electrostatically attracted to attract the transfer paper 6 fed from the paper feeder 5 to the belt 11. The charging means 12 for charging is provided, and the discharging means 1 is provided on the transfer paper unloading side of the belt 11 to prevent the accumulation of charges.
3 is provided. The polarity of the electrostatic attraction charging means 12 may be either positive or negative, and the electrostatic attraction charging means 12 may be used.
A counter electrode 14 is provided so as to face the above, and the efficiency of the charging means 12 is improved.

Reference numeral 15 designates a conductive roller provided at a position where the transfer paper 6 comes into contact with the photosensitive member 1.
As a result, the transfer paper 6 is brought into close contact with the photoconductor 1 and at the same time the toner image is transferred by receiving an electric field. Reference numeral 16 is a transfer paper peeling means provided at the rear end portion of the belt 11, and 17 is a belt cleaning means.

The transfer sheet 6 fed from the sheet feeding section 5 is attracted to the belt 11 by the electrostatic attraction charging means 12 and conveyed, and the roller 15 is contacted with the photosensitive member 1.
The toner image is transferred while being brought into close contact with the photoconductor 1 by the above, and is further conveyed, is further conveyed, is peeled from the belt 11 by the transfer paper peeling means 16, and is sent to the fixing section 8.

In the above device, the volume resistivity is 10 ¹² Ω
Using the belt 11 of cm, the moving speed of the photoconductor 1 υ _{P / R} =
270 mm / sec, roller 15 applied voltage 2.0 KV
Then, the following Table 1 shows the occurrence status of the hollow character due to the moving speed υB of the belt 11.

[0011]

[Table 1]

In the above experiment, the belt 11 and the transfer paper 6 did not shift before and after the transfer portion. Although it is not clear why the above results were obtained, the transfer paper 6
If the speeds of the photoconductor and the photoconductor 1 are different, the transfer paper 6
It is presumed that the force in the moving direction is applied between the toner and the photoconductor 1 to cause the toner to roll, the shearing force to the toner layer, and the like. Further, although a strict boundary line is not clear, it is important from Table 1 above that at least the speeds of the transfer paper 6 and the photoreceptor 1 as a toner support are different in order to suppress the generation of hollow characters. I understand.

However, if the speed difference υ _B −υ _{P / R} between the two is too large, the finally obtained copy image is reduced or enlarged in the rotation direction of the photoconductor 1 with respect to the original image, or the copy image is disturbed. Will occur. Therefore, it is necessary to set the speed difference υ _B −υ _{P / R} within the range where these problems do not occur. However, the original image is digitally read using the original reading device and then written on the photoconductor 1 or the dielectric. In the copying machine or printer which is designed to be inserted, the occurrence of the above-mentioned problem can be eliminated by reducing the reading speed and the writing speed and correcting the writing speed.

Next, the experimental results will be described. A test of sequentially copying plural color toners onto a transfer paper 6 made of plain paper by using a copying machine of own company (FX6500 manufactured by Fuji Xerox) and a developer for the copying machine. went. After developing the toner of the first color, the toner image was transferred to the transfer paper 6, and the toner image developed with the toner of the second color without fixing was transferred onto the transfer paper 6 to which the toner of the first color was transferred. Hereinafter, the above operation was repeated to transfer the toner of the third color. At this time, the moving speed υ _{P / R} of the photoconductor 1 is 80 mm / sec, the belt 11
Moving speed υ _B is 80mm / sec, 81mm / sec
There are two ways.

As a result, the moving speed υ _B of the belt 11 is 8
In the case of 0 mm / sec, while a hollow character occurred in the portion where the toner images of the second and third colors overlap,
When the moving speed υ _B of the belt 11 was 81 mm / sec, no hollow character was generated. Also from the above, an appropriate difference is provided between the moving speed υ _{P / R of the} photosensitive member 1 and the moving speed υ _B of the belt 11, that is, the transfer paper conveying means has a speed difference with respect to the toner image support. By doing so, it became clear that the occurrence of hollow characters could be prevented.

In the above embodiment, the speed υ of the belt 11 is
The moving speed υ _{P / R} of the photosensitive member 1 is changed by changing _B. However, if the moving speeds of the photosensitive member 1 and the transfer paper 6 can be set to be different from each other, the above-mentioned embodiment is used. It is not limited.

[0017]

As described above in detail, the present invention provides a transfer sheet conveying means for conveying a transfer sheet made of a cut sheet to the toner image support, and the transfer sheet is brought into close contact with the toner image support at the same time as the toner image. And a roller for applying an electric field for transferring the electric field to the transfer sheet, and the transfer sheet conveying means has a speed difference with respect to the toner image support,
It is possible to reliably prevent the occurrence of a so-called hollow character in which a part of the copied image is hollow.

Further, since it suffices that the moving speed of the photosensitive member and the moving speed of the transfer paper are made different, the present invention can be easily implemented in an existing copying machine or the like.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment according to the present invention.

FIG. 2 is an enlarged side view of a main part of an embodiment according to the present invention.

FIG. 3 (a) is an explanatory view showing a situation of occurrence of a hollow character. (B) An explanatory view showing a situation of occurrence of a hollow character.

[Explanation of symbols]

 1 ... Photoconductor, 6 ... Transfer paper, 7 ... Transfer part.

Claims (1)

[Claims] 1. A transfer device for transferring a toner image formed on a surface of a toner image support through a latent image forming step and a developing step onto a transfer paper at a transfer section, wherein the toner image support is made of cut paper. Transfer sheet conveying means for conveying the transfer sheet,
A roller for applying an electric field for transferring the toner image onto the transfer paper at the same time when the transfer paper is brought into close contact with the toner image support, and the transfer paper conveying means has a speed difference with respect to the toner image support. A transfer device having.