JPH01217475A - Image forming method - Google Patents

Abstract

PURPOSE:To improve image quality by exposing by means of projecting light consisting essentially of wavelength light of <=620[nm]. CONSTITUTION:When image information is performed on a positively charged organic photoconductor (OPC), exposure is performed by the projecting light consisting essentially of the wavelength light of <=620[nm]. Thus, the fatigue of the positive electrification OPC due to the projecting light when the exposure is performed is reduced, and the raising of accumulated electric charge and the reduction of electrifying property are eliminated even if the image forming process is repeated. And besides, an excellent image without fogging nor image flow is obtained and an image can properly be repeated even if an original is red-colored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an image forming method for forming an image by positively charging an organic photoconductor in an electrophotographic apparatus or the like.

(Prior Art) Conventionally, photoreceptor materials for electrophotographic devices such as copying machines and laser printers include selenium (Se) and selenium-tellurium [5e-
Inorganic materials such as Te] alloy, arsenic selenium (AS2Se), and zinc oxide (ZnO) are mainly used.

However, selenium (Se), arsenic selenium [AS2S
e, ] are harmful to the human body, so the used photoconductor must be collected after use. In addition, in the case of selenium (Se), the crystallization temperature is 50 to 60 ('
C), it is easy to crystallize, and during repeated copying, a residual charge is generated in the crystallized part, deteriorating the image quality, and its low hardness makes it difficult to achieve a long life. There is a problem that there is no arsenic selenium (AS2Se3
) has the problem that photoreceptor characteristics such as charging ability and sensitivity change significantly due to optical fatigue, and temperature characteristics are also poor. Zinc oxide (ZnO) has a problem in that its surface is soft and easily peels off, making it difficult to achieve a long service life.

For this reason, in recent years, as a solution to the above problems, photoreceptor materials such as amorphous silicon (hereinafter referred to as A-3I) and organic photoconductor (hereinafter referred to as OPC), which are non-polluting and do not require recovery processing, have been developed. Application of this method is being considered. While a-3L has the advantage of having high Vickers hardness, excellent printing durability and impact resistance, and high spectral sensitivity in a wide wavelength range from the entire visible light region to the near-infrared region, on the other hand, It has low charging ability, tends to cause image blurring, and has high Vickers hardness, so it has excellent printing durability, and is mainly used for high-speed equipment, but due to high manufacturing costs, medium and low-speed printing requires lower prices. It is said that it is impossible to apply this to devices. On the other hand, OPC is cheaper than a-5i and can be applied to medium- to low-speed equipment, and depending on material selection, printing durability and sensitivity characteristics can be significantly improved compared to conventional methods. In addition, compared to negatively charged OPC, it is easier to obtain toner, and therefore a charge transport layer (hereinafter referred to as CTL) is particularly provided on a conductive support.

) and a charge generation layer (hereinafter referred to as CGL) are successively stacked to form a positively charged OPC.

However, with such a positively charged OPC, although a good image can be obtained initially, the accumulated charge increases as shown in Figure 4 [A] during repeated copying, and the white background during exposure increases. This accumulated charge affects the area, causing fog in the image and reducing the charging ability.
A problem arises in that the image becomes faint and the image quality is significantly degraded.

Furthermore, since the positive IF electroopc has sensitivity in the long wavelength range, it also has the problem of poor reproducibility of red parts such as stamps on originals, making it impossible to apply it.

(Problems to be Solved by the Invention) Conventionally, positively charged OPCs generate accumulated charge while repeating the image forming process, which increases the residual potential and deteriorates the charging ability, causing fogging and fogging on the image. There are problems in that density decreases, image quality is significantly degraded, and reproducibility of red originals is poor.

Therefore, the present invention aims to eliminate the above problem, and is aimed at eliminating the above-mentioned problem.
Even if the image forming process is repeated using C, a good image without fogging or loss of density can be obtained.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the present invention aims to improve image quality by performing exposure with irradiation light whose main component is light with a wavelength of 620 [nm] or less.

(Function) The present invention uses the above-mentioned means to prevent positively charged OPC from fatigue during exposure, thereby preventing an increase in accumulated charge and a decrease in charging ability, and further improving the reproducibility of red originals, thereby improving image quality. To obtain good image quality without streaks or fog.

(Example) First of all, the regular belt'? The principle of generation of accumulated charge and reduction of charging ability of r10 P C will be explained. That is, positively charged OPCs are generally used as CTLs and CGLs on conductive supports.
It has a layered structure in which layers are sequentially laminated, and has spectral sensitivity over all wavelengths. During exposure, hole/electron pairs are generated within the CGL due to light irradiation, but among these, the electrons reach the surface, neutralize the positive charge on the positively charged 020 surface, and form a static charge on the positively charged OPC. While forming a latent image, the holes reach the conductive support via the CTL. However, at this time, some of the holes are trapped at the boundary between the CGL and CTL, and while copying is repeated, the trapped holes are sequentially increased and become the accumulated charge of the positively charged opc. On the other hand, CGLs and CTLs tend to become fatigued as the longer wavelength light in the irradiated light increases, resulting in a significant reduction in charging ability.

Therefore, in order to prevent an increase in the accumulated charge of the positively charged OPC and a decrease in the charging ability, it is necessary to remove long wavelength light from the irradiation light.

Next, one embodiment of the present invention will be described with reference to FIGS. 1 to 4. (16) is a drum-shaped photoreceptor made of positively charged OPC, and the conductive substrate is aluminum [A
1] on the support (17) by the manufacturing method described below.
A TL (18a) and a CGL (18b) are sequentially stacked. That is, first, the hydrazone shown by the formula is a binder resin, and the formula...
A support (17) is immersed in a liquid obtained by mixing phenoxy represented by formula 2) in a cyclohexane solvent, and drying it to form a CTL (18a).

Next, the phenoxy represented by (2nd formula) is mixed with the Nafur AS azo pigment represented by the formula (3rd formula) and the hydrazone represented by (1st formula), and these are mixed into 1, 1, 2. - The support (17) having the CTL (18a) is immersed in a liquid dissolved in a solvent of trichloroethane, which is further dried, and the CGL (18b)
form. On the other hand, around the photoconductor (16) are a charger (20), an exposure device (21), and a developing device (22).
, transfer charger (23), peeling charger (24),
Image forming means such as a cleaning device (26) and a static elimination lamp (27) consisting of a halogen lamp are provided.

The exposure device (21) is provided with an exposure lamp consisting of a fluorescent lamp.

When copying is started, the photoreceptor (16) is rotated in the direction of the arrow X, and the charger (2) is rotated in the direction of the arrow X.
4), the photoconductor (16) is uniformly positively charged, and then an exposure process is performed, but since all of the exposure light has a short wavelength of 620 [nm] or less, the photoreceptor (16) completes the exposure without being fatigued. do. After this, the developing device (22), the transfer charger (2
3) A copy image is formed on a sheet of paper (not shown) via a peel charger (24), while a photoreceptor (16)
Furthermore, the static elimination lamp (2) passes through the cleaning device U (26).
7), but the static elimination lamp (27) reaches 620 [n
m] Since it is made of a halogen lamp that contains longer wavelength light, the light attenuation characteristics of the photoreceptor (16) have some sagging, but there is no residual charge on the surface of the photoreceptor (16). The static electricity is removed and the next copy is made possible.

In addition, when copying was repeated in this way, the photoreceptor (
16) The accumulated charge is kept low as shown in Figure 3,
There was no fogging in the copy image, and no decrease in density due to a decrease in charging ability was observed. With this configuration, 620 [n
m] By cutting out all of the longer wavelength light, fatigue of the photoreceptor (16) can be significantly reduced, and an increase in accumulated charge and a decrease in charging ability due to repeated copying can be prevented, and fogging and a decrease in density can be prevented. It is possible to obtain a good image with no red color, and furthermore, the reproducibility of red originals can be improved.

Note that the present invention is not limited to the above-mentioned embodiments and can be modified in various ways. For example, considering the fatigue of positively charged OPC, it is desirable to cut out all long wavelength light in the exposure light. Some long-wavelength light may be included in the exposure light as long as it is less than 35% of the total energy, which is a range that does not significantly affect fatigue. When a certain fluorescent lamp is used as the exposure light source, there is no need to use a filter to cut off long wavelength light, and costs can be reduced. or,
From the point of view of fatigue of positively charged OPC, it is preferable to cut long wavelengths in the same way as exposure light during static elimination, and the image forming means is not limited to that of the embodiment, and excess light should be removed after development and before transfer. It is also possible to provide a pre-transfer charger for erasing residual toner charges, or a static elimination charger for erasing residual toner charges after transfer.

〔Effect of the invention〕

As explained above, according to the present invention, the fatigue of the positively charged OPC due to the irradiation light during exposure is small, and even if one image forming process is repeated, the accumulated charge may increase or the charging ability may be reduced. It is possible to obtain good images without fogging or image blurring.

The life of the positively charged OPC can be extended. Furthermore, if the wavelength of the exposure light is at least 620 [nm] or less, the image can be reproduced well even if the original is red, making it possible to apply it to a two-color printing device and reducing its cost. . Further, if the static eliminating light shown in the embodiment is used, residual charges will not be generated during static neutralization, and will not have an adverse effect on the next image formation.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention.
The figure is a schematic cross-sectional view, Figure 2 is a partial cross-sectional view showing the photoreceptor, Figure 3 is a graph showing the accumulated charge due to repeated copying, and Figure 4 is a graph showing the repeated copying in a conventional device. It is a graph showing accumulated charge due to copying. 16... Photoreceptor, 17... Support, 18a-CTL, 18b-CGL
, 2111. Exposure device, 27... Static elimination lamp, 28... Exposure lamp.

Claims (1)

[Scope of Claims] 1. In an image forming process performed on a positively charged organic photoconductor, an image characterized in that the exposure process is performed with irradiation light whose main component is light with a wavelength of 620 [nm] or less. Formation method.