JPS5945474A - Copying device - Google Patents

Abstract

PURPOSE:To improve a transfer rate and to stabilize conveyance and sepn., by impressing the DC bias of the polarity reverse from the electrostatic charge on a photoreceptor in the stage of irradiation for pre-transfer exposing. CONSTITUTION:A pre-transfer exposing lamp 10 is provided between a developing device 5 and a transfer electrode 7 at the circumferential edge of a photosensitive drum 1 of Se-Te. A transparent electrode 111 vapor deposited with palladium oxide is provided on a transparent substrate 11 to avoid shielding the irradiation light of the lamp 10 between the drum 1 and the lamp 10. The electrode 111 is so formed as to maintain 1mm. space from the peripheral surface of the drum 1. A prescribed minus voltage is impressed from a DC power source V to the impressing means of the electrode 111 simultaneously with irradiation by the lamp 10, whereby the solid black image having high uniformity and 100% blacking area rate is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a copying apparatus that imprints an electrostatic latent image on an image support, forms the image with a developer, and then transfers the image onto recording paper.

First, the general structure and functions of an electrophotographic copying apparatus will be explained with reference to FIG. 1, and then the present invention will be explained. S on the surface
An electrophotographic photoreceptor such as E or 5e-Te is vapor-deposited or coated on a drum surface of 1 m as an image support.
is rotated 1-6 degrees clockwise.The image of the document placed on the document table 2 is focused on the photosensitive drum 12 by an optical system 3 consisting of a lens, a reflecting mirror, and the like. The photoreceptor, which is uniformly distributed on the circumferential surface of the photoreceptor drum 1 by the charging electrode 4, forms a latent image by the optical system 3. The latent image is produced by the developing device 5.
It is developed when passing through the latent image area, and toner adheres to the latent image area, resulting in no toner image. On the other hand, the recording paper fed by the paper feed roller 6 in synchronization with the rotation of the photoconductor drum 1 comes into contact with the circumferential surface of the photoconductor drum 1 at the transfer electrode 7, and the toner on the photoconductor is transferred onto the recording paper. toner transfer is performed. The recording paper onto which the toner has been transferred is separated from the photosensitive drum 1 at the next eight separation electrodes, fixed, and then discharged from the apparatus. Further, the photosensitive drum 1 that has undergone the transfer and external processes is removed from the toner still attached to the surface of the photosensitive drum in the cleaning section 9, and one cycle is completed.

Here, the toner image on the photoreceptor that has been developed by the developing device 5 is transferred onto the recording paper at the transfer electrode 7 section, and further transferred to the recording paper θ from the photoreceptor drum 1 at the separation electrode 8 section.
), but the present inventors believe that the 1V difference between the developing section rlj,5 by the developing section and the transfer 'Jj'', part by the transfer electrode 7
'o discovered the effect of irradiating the photoreceptor surface with a lamp to perform pre-transfer exposure, and filed a patent application in 1982-1G10h.
No. 4, Patent Application No. 1982-161055, Patent Application No. 56-16
No. 1056 and Japanese Patent Application No. 161057/1984. That is, by performing pre-transfer exposure, the surface level of the photoreceptor after development is lowered, increasing the efficiency of transferring the toner image to the transfer paper and ensuring stable electrostatic separation regardless of the original density. be able to.

Table 1 shows the relationship between the irradiation amount and separation performance when pre-transfer exposure is performed, and the discharge current of the transfer electrode is 30μA1
A, which was carried out under the condition of a discharge current of 130 μA of the separated m-pole.
It is.

Table 1 Pre-transfer exposure amount and minute I;l success rate [%] Table 2 shows the relationship between pre-transfer j174 light irradiation and transfer rate under the same conditions as Table 1.

Table 2 Pre-transfer exposure and transfer efficiency Although pre-exposure irradiation improved the transfer rate and separation performance, on the other hand, it had the disadvantage of causing a decline in the quality of the copied image. Ru. The deterioration in image quality is noticeable for, for example, a uniform solid black image that occurs when no illumination lamp is irradiated, but is not noticeable for general images. When pre-transfer exposure is performed on a solid black image, fine white areas are generated in the solid black portion, and only a rough black copy image of low quality is obtained.

FIG. 2 shows the relationship between the pre-transfer exposure amount and the blackened area ratio of the solid black portion of the copy image. Here, the blackened area rate is 100
% indicates a uniform solid black image6
1. It can be seen from FIG. 2 that pre-transfer exposure irradiation (therefore, fine white areas are generated and the blackening rate per unit area is reduced).

The purpose of the present invention is to prevent the deterioration of copy image quality due to the above-mentioned pre-transfer exposure irradiation, and to improve the transfer rate and separation performance. In a copying device that forms an electrostatic latent image on a surface, forms an image with a developer, and transfers the image to recording paper, an image support on which an image is formed with the developer 0) Exposure by irradiating the development surface with a lamp This is achieved by a copying apparatus characterized in that it is equipped with a lamp and an application means for applying a DC voltage.

The authors of the present invention clarified the cause of the above-mentioned σ) copy image deterioration due to pre-transfer topal light as a result of theoretical investigation. Image deterioration occurs due to the electric field structure on the photoreceptor when light is irradiated onto the photoreceptor from above the toner after development, and this phenomenon has an electric field structure similar to that in cascade development. Therefore, in order to produce the same effect as the developing electrode f during the pre-transfer exposure, the direct i'g
r, apply a bias voltage, and re! during irradiation. Element - H θ
) M, changing the shape of the field and doing so is non-invention.

The present invention will be explained in detail below with reference to the drawings.

FIG. 3 shows a sectional view of the main parts around the photoreceptor drum according to the present invention. At the peripheral edge of the 3e-Te type photoreceptor drum 1, a pre-transfer exposure lamp is installed between the developer mounting 5 and the transfer electrode 7. 10 was set. As the pre-transfer exposure lamp 10, a cold cathode lamp with a peak wavelength of 400 nm is used.

ζ between the la optical drum 1 and the pre-transfer exposure brush 10
A transparent electrode 111 on which palladium oxide is vapor-deposited is provided on a transparent support 11 such as a transparent polyester neutral base so as not to block the irradiation light from the pre-transfer exposure lamp. Keep the distance between the dragons KL 7:2.

In this way, along with the irradiation by the pre-transfer exposure lamp 10, a voltage of minus 1.7 KV was applied to the application means of the transparent electrode 111 from the DC power supply VK. By applying a bias together with such irradiation, it was possible to obtain a solid black image with a highly uniform blackened area ratio of 100%, similar to that obtained when the pre-transfer exposure irradiation was not performed.

This is considered to be because the electric field components on the photoreceptor were changed by applying a slight bias during the pre-transfer exposure irradiation, and the directions of the electric lines of force could be aligned in the normal direction.

As mentioned above, by applying a DC pulse with the opposite polarity to the charge on the photoreceptor during pre-transfer exposure, it is possible to prevent image deterioration, and also to prevent the transfer as described above. The effect of pre-exposure irradiation can be maintained as is, improving the transfer rate and stabilizing general feeding and separation as shown in Figure 57.
The same results as in Tables 1 and 2 were obtained regarding the separation success rate and transfer efficiency when a DC bias voltage was applied at 1.6r).In other words, the present invention A) I was able to achieve my goal.

f (In the example, the distance between the transparent electrode and the yC4 body is 1
However, it is not necessarily the same, and it may be determined based on the setting of the applied voltage. Also transparent m t+TJ
In addition to palladium oxide, a material with high transmittance such as indium oxide may be used for j, or another material may also be used to adjust the amount of lamp light.

[Brief explanation of the drawing]

Figure 1 is a schematic layout showing the 4u' configuration of an electrophotographic copying machine.
FIG. 2 is a graph showing the relationship between the pre-transfer 1i light 11 and the blackened area ratio, and FIG. 3 is a sectional view of the main parts around the photosensitive drum according to the present invention. 1... Photosensitive drum, 5... Developing device, 7...
・Transfer electrode, 10... Pre-transfer exposure lamp, 1
1...Transparent support, 1]1...Transparent electrode $1
1a 4gt

Claims (2)

[Claims] (1) In a copying device that forms an electrostatic latent image on an image support, forms the image with a developer, and transfers the image to recording paper, the development surface of the image support on which the image is formed with the developer. What is claimed is: 1. A copying apparatus comprising: an exposure lamp for performing lamp irradiation; and applying means for applying a DC voltage. (2) The copying apparatus according to claim 1, wherein a transparent Tff and an electrode plate are used as the DC voltage applying means.