JPH10333393A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance image forming device suitable to the high speed color printing. SOLUTION: This image forming device 18, is composed by arraying plural image forming components such as developing device 12 forming an electrostatic latent image on a surface of a photoreceptor 8 and forming the color toner image corresponding to the electrostatic latent image on the surface of photoreceptor 8, the transferring device 14 transferring the toner image on a transferred material 13, cleaning means 15 removing the residual toner on the photoreceptor surface after transferring, and destatisizing means 16 removing the residual electrostatic latent image after transferring, while composing the photoreceptor 1 mounted on the image forming component 7a forming the black color toner image by an amorphous silicon carbide photoconductive layer whose thickness is made beyond 30 μm, and making the static charge difference below 200 V, as compared to the static charge on the respective image forming component on which the OPC photoreceptor for forming the colored toner image other than the black color toner image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem type electrophotographic image forming apparatus equipped with a negatively charged photosensitive member comprising an amorphous silicon carbide photoconductive layer.

[0002]

2. Description of the Related Art As a color printer which has already been commercialized, there is an image forming apparatus of a tandem type electrophotographic system, and a photosensitive member mounted thereon is constituted by a negative charging type OPC. The charging ability of this OPC photoreceptor is -8.
Since the voltage can be increased to about 00V, the adhesion of the color toner becomes easy.

[0003]

However, the above O
When an image forming apparatus equipped with a PC photoreceptor is applied to high-speed color printing, there is a problem that an OPC photoreceptor is not suitable because of poor abrasion and durability.

For this reason, at least the photosensitive member using a black toner image is replaced with an amorphous silicon photosensitive member which has been commercialized, but the charging ability is lower than that of the OPC photosensitive member. However, satisfactory printing performance could not be achieved.

In general, in the case of a color printer in which a plurality of photoconductors are arranged for one image forming apparatus, if photoconductors having different photoconductive layers are arranged, the required performance is required due to the difference in performance. There is also a problem that coloring cannot be obtained.

In view of the above circumstances, the inventor of the present invention has intensively studied and found that a tandem-type electrophotographic color printer not only actually performs color printing but also performs color printing.
Attention is paid to the fact that monochrome (black) printing is frequently performed, and monochrome printing is often used more frequently than color printing. Therefore, it is mounted on an image forming element that forms a black toner image. Photoreceptor thickness 30 ~ 100μm
Of an amorphous silicon carbide photoconductive layer (hereinafter, amorphous silicon carbide is abbreviated as a-SiC) to form a colored toner image other than a black toner image. In comparison, it was found that, by setting the charging difference to 200 V or less, even if different types of photoconductors are mounted on a common image forming apparatus, the image forming apparatus is sufficiently practical as a color printer.

Accordingly, the present invention has been accomplished based on the above findings, and an object of the present invention is to provide an image forming apparatus suitable for high-speed color printing.

Another object of the present invention is to improve the durability against monochrome printing, so that the overall printing performance can be maintained for a long period of time even when properly used for color printing. To provide an image forming apparatus.

[0009]

According to the present invention, there is provided a tandem-type electrophotographic image forming apparatus, comprising: a photoreceptor; charging means for applying a negative charge to the surface of the photoreceptor; Developing means for forming an electrostatic latent image on the surface of the photoreceptor by means of the charging means and the exposure means, and forming a colored toner image corresponding to the electrostatic latent image on the surface of the photoreceptor; Image forming apparatus comprising: transferring means for transferring a toner image to a material to be transferred; cleaning means for removing residual toner on the surface of a photoreceptor after transfer; and charge removing means for removing a residual electrostatic latent image after transfer And a plurality of image forming elements are arranged, and the photosensitive member mounted on the image forming element for forming a black toner image has a thickness of 30 mm.
μm or more of an a-SiC photoconductive layer, and compared with charging in an image forming element equipped with an OPC photoreceptor to form a colored toner image other than a black toner image.
It is characterized by having a charge difference of 0 V or less.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Photoreceptor Configuration FIG. 2 shows a layer configuration of a photoreceptor 1 relating to an image forming element for forming a black toner image according to the present invention.
A vacuum deposition method, an active reaction deposition method, an ion plating method, an RF sputtering method, a DC sputtering method, an RF magnetron sputtering method, a DC magnetron sputtering method, a thermal CV
A film is formed by a D method, a plasma CVD method, or the like. The photosensitive layer 3 is formed by sequentially laminating a carrier injection blocking layer 4, a photoconductive layer 5, and a surface protective layer 6, for example.

The substrate 2 is made of copper, brass, SUS, Al, N
i. A material made of a metal conductor such as i, or an insulator such as glass or ceramic coated with a conductive thin film. The substrate 2 may be a sheet-shaped, belt-shaped or web-shaped flexible conductive sheet. Such a sheet may be a metal sheet such as SUS, Al, Ni, or a polymer resin film such as polyester, nylon, or polyimide. Metal such as Al, Ni or tin oxide,
A transparent conductive material such as indium tin oxide (ITO) or an organic conductive material coated by vapor deposition or the like and subjected to a conductive treatment is used.

The carrier injection blocking layer 4 is made of a-SiC,
Amorphous silicon (hereinafter abbreviated as a-Si),
It is formed by amorphous silicon nitride or the like.

The photoconductive layer 5 is made of a-SiC.
The relative dielectric constant of this a-SiC is smaller than that of a-Si, so that the charging ability is improved.

When the thickness of the photoconductive layer 5 is set to 30 μm or more, the charging ability of the OPC photoreceptor can be considerably approximated. Further, the thickness is 30 to 100 μm, preferably 3
It is desirable to set the thickness to 0 to 70 μm. If the thickness is less than 30 μm, dark decay becomes poor.

The surface protective layer 6 is also made of a-Si having a high insulating property.
It may be made of C, or may be made of amorphous silicon nitride, amorphous silicon oxide, or the like.

In the photosensitive member mounted on the image forming element for forming a black toner image, the above-mentioned layer structure can be used to charge the conventionally known OPC photosensitive member (for example, about 800
V), that is, a charge difference of 200 V or less compared with the OPC photoconductor, and
By such a charging difference, an image forming apparatus suitable for high-speed color printing can be obtained.

The diagram 1 of an image forming apparatus is an image forming apparatus of the present invention, first shows the principle of the imaging element 7 of the printer manner according to the present invention in FIG. Reference numeral 8 denotes a photoreceptor, a corona charger 9 serving as a charging unit on the peripheral surface of the photoreceptor 8, an exposure unit 10 (LED head) serving as an exposure unit that irradiates light after the charging, and a photoconductor 8 A developing device 12 having a toner 11 for forming a toner image on the surface of the transfer material 1
3. A transfer device 14 serving as a transfer means for transferring the toner image onto the photosensitive member 3, a cleaning means 15 for removing residual toner on the surface of the photoreceptor after the transfer, and a charge removing means 16 for removing a residual electrostatic latent image after the transfer. It is. Reference numeral 17 denotes the material to be transferred 1
3 is a fixing device for fixing the toner image transferred to 3 by heat or pressure.

In the Carlson method, the following processes are repeated. The peripheral surface of the photoconductor 8 is charged by the corona charger 9. By exposing the image with the exposure device 10, an electrostatic latent image as a potential contrast is formed on the surface of the photoconductor 8. This electrostatic latent image is developed by the developing machine 12. By this development, the colored toner adheres to the surface of the photoreceptor by electrostatic attraction with the electrostatic latent image and is visualized. The toner image on the surface of the photoreceptor is electrostatically transferred from the back surface of the transfer material 13 such as paper by applying an electric field having a polarity opposite to that of the toner, whereby an image is obtained on the transfer material 13. The cleaning unit 15 mechanically removes residual toner on the surface of the photoconductor. The entire surface of the photoconductor is exposed to intense light, and the remaining electrostatic latent image is removed by the charge removing means 16. The image forming element 7 has a printer configuration. However, if an optical system such as a lens or a mirror that transmits light reflected from a document is used instead of the exposure device 10, an image forming apparatus having a copier configuration can be obtained.

Next, in the image forming apparatus 18 shown in FIG.
a is an image forming element for black (indicated by K in the figure),
7b is an image forming element for yellow (displayed as Y in the figure), 7c is an image forming element for cyan (displayed as C in the figure), and 7d is an image forming element for magenta (displayed as M in the figure). It is. Then, the photosensitive member 1 is mounted on the image forming element 7a (K), and the other image forming elements 7b (Y), 7
A known OPC photoconductor is mounted on c (C) and 7d (M). Further, a sheet as the material to be transferred 13 is placed on the transfer belt 19 and moved in the direction of the arrow.

Thus, according to the image forming apparatus 18 having the above configuration, the charging of the photosensitive member 1 of the image forming element 7a (K) is
By providing a charge difference of 200 V or less as compared with the C photoconductor, it is possible to provide a color image forming apparatus in which printing unevenness does not occur and a clear color image is obtained.
In addition, by improving the durability of the photoreceptor 1 of the image forming element 7a (K), high-speed color printing can be performed, and the quality as a whole can be extended even when used selectively between color printing and monochrome printing. Can be maintained over time.

[0021]

【Example】

(Example 1) Photoconductor 1 of image forming element 7a (K) was manufactured as follows. That is, the photosensitive layer 3 is formed on a cylindrical substrate made of Al having a purity of 99.9% by a plasma CVD method.
The photosensitive layer 3 is formed of boron 1500p
pm, 1.0% oxygen, 0.7% nitrogen a-Si carrier injection blocking layer 4 (2.5 μm thick), boron 0.5p
pm, a-SiC photoconductive layer 5 (thickness: 33 μm) containing carbon at 15.5 atomic% with respect to silicon, insulating a-SiC
It is formed by sequentially laminating a surface protection layer 6 of SiC (thickness 0.7 μm).

According to this plasma CVD method, silane gas, methane gas, hydrogen gas, diborane gas, and nitrogen oxide gas are used as starting material gases, and various gases are appropriately introduced into the reaction vessel according to the formation of each layer. Subsequently, each layer is sequentially provided by generating plasma at a high voltage. For the photoconductive layer 5, the gas ratio of methane gas to silane gas is preferably set to 0.1 to 0.5%.

As for the other OPC photosensitive member, an undercoat layer (intermediate layer) and a 1 μm thick
m and a carrier transporting layer having a thickness of 15 to 40 μm, which are sequentially laminated, and the undercoat layer is made of a water-soluble or alcohol-soluble resin, a thermosetting resin or a photo-setting resin. The carrier generation layer is composed of a resin binder in which fine-particle pigments are dispersed, and the carrier transport layer has an electron-donating property having a large hole mobility, and the carrier transport material is dispersed in the resin binder. It is a dissolved layer.

The photosensitive member 1 of the image forming element 7a (K)
Was -620 V, the OPC photosensitive member was -800 V, and the difference between the two was 180 V.

The various photosensitive members produced as described above are mounted on the respective image forming elements 7a, 7b, 7c, 7d.
When color printing was performed using the image forming apparatus thus obtained, an excellent color image was obtained at a printing speed of 12 sheets / min.

(Example 2) Of the image forming apparatuses of (Example 1),
The thickness of the photoconductive layer 5 of the photoconductor 1 was increased from 33 μm to 50 μm, and an image forming apparatus having the same other configuration was manufactured. The charging ability of the photoconductor 1 of this image forming element 7a (K) is -750V, and the charging difference is 50
V. When color printing was performed in the same manner, an excellent color image was obtained at a printing speed of 12 sheets / min.

(Example 3) Of the image forming apparatuses of (Example 1),
An image forming apparatus was manufactured in which the thickness of the photoconductive layer 5 of the photoreceptor 1 was reduced to 28 μm and the other configuration was the same. Also,
The charge of the photoconductor 1 of the image forming element 7a (K) is -580V.
And the charge difference was 220V. When color printing was performed similarly, high-speed printing at a printing speed of 12 sheets / minute could not be performed, and color printing unevenness occurred.

[0028]

As described above, according to the image forming apparatus of the present invention, the photoreceptor mounted on the image forming element for forming a black toner image is constituted by an a-SiC photoconductive layer having a thickness of 30 μm or more. A high-performance color printer suitable for high-speed color printing can be provided by using a charging difference of 200 V or less as compared with the charging of an image forming element equipped with an OPC photoconductor to form a colored toner image other than a black toner image. Was.

Further, according to the present invention, by increasing the durability against monochrome printing, it is possible to use the same for color printing satisfactorily, and to maintain long-term reliable image performance over the long term. A forming device could be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus of the present invention.

FIG. 2 is a cross-sectional view illustrating a layer configuration of a photoreceptor according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of an image forming element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 8 Photoreceptor 2 Substrate 3 Photosensitive layer 5 Photoconductive layer 6 Surface protective layer 7, 7a, 7b, 7c, 7d Image forming element 9 Corona charger 10 Exposure device 11 Toner 12 Developing machine 13 Transfer material 14 Transfer device 15 Cleaning means 16 Static elimination means 18 Image forming apparatus 19 Transfer belt

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03G 15/00 303 G03G 15/02 101 15/02 101 9/08 361

Claims (1)

[Claims] 1. A photoreceptor, a charging means for imparting a negative charge to the surface of the photoreceptor, and an exposure means for irradiating a charged area of the photoreceptor with light, wherein the photosensitive means is exposed to light by the charging means and the exposure means. Developing means for forming an electrostatic latent image on the surface of the body, forming a colored toner image corresponding to the electrostatic latent image on the surface of the photoreceptor, and transferring means for transferring the colored toner image to a material to be transferred A black toner image is formed by arranging a plurality of image forming elements provided with cleaning means for removing residual toner on the photoreceptor surface after the transfer and charge removing means for removing the residual electrostatic latent image after the transfer. The photoreceptor mounted on the image forming element is composed of an amorphous silicon carbide photoconductive layer having a thickness of 30 μm or more, and is formed on the image forming element on which the OPC photoreceptor is mounted to form a colored toner image other than a black toner image. Compared with that charge, the image forming apparatus of a tandem type electrophotographic method, characterized in that the following charge difference 200V.