JPH1152599A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color printer which is suitable to high speed color printing and whose performance is excellent. SOLUTION: Plural image forming elements 7a, 7b, 7c and 7d where a developing machine 12 forming an electrostatic latent image on the surface of a photoreceptor 8 and forming a colored toner image corresponding to the electrostatic latent image on the surface of the photoreceptor 8, a transferring unit 14 transferring a toner image on a material to be transferred 13, a cleaning means 15 removing residual toner on the surface of the photoreceptor 8 after transfer and a discharging means 16 removing a residual electrostatic latent image after transfer are disposed are arrayed in this image forming device 18 of a tandem type electrophotographic system. Also, the photoreceptor loaded on the image forming element 7a forming a black toner image is formed so as to have a layer constitution where an a-Si photoconductive layer and an a-SiC surface layer whose dynamic indentation hardness is 45-220 kgf/mm<2> are successively laminated and the photoreceptors loaded on the image forming elements forming the colored toner image other than the black toner image are constituted of an OPC. Then, the processing speed of each photoreceptor 8 is set at >=200 mm/second.

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 photoreceptor made of an amorphous silicon 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.

[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.

Accordingly, an image forming apparatus in which a photosensitive member entirely composed of an amorphous silicon photoconductive layer (hereinafter, amorphous silicon is abbreviated as a-Si) has been proposed. There is a problem that a contrast cannot be obtained in each color of yellow.

In view of the above circumstances, the present inventor has made intensive studies and found that in a tandem-type electrophotographic color printer, in addition to actually performing 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. A layer in which an a-Si photoconductive layer of a photoreceptor and an amorphous silicon carbide surface layer having a dynamic indentation hardness of 45 to 220 kgf / mm ² (hereinafter, amorphous silicon carbide is abbreviated as a-SiC) are sequentially laminated. In the configuration, the photoconductors mounted on the image forming elements that form a colored toner image other than the black toner image are further configured by OPC, and the process speed of each photoconductor is increased to 200 mm / sec or more. Even if different types of photoconductors are mounted on a common image forming apparatus, image deletion and image deterioration do not occur, and a color printer for high-speed color printing can be used. Sufficiently practical resistance was found out as an image forming apparatus in Te.

Incidentally, 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, coloring as required due to a difference in performance between the photoconductors is required. Is not obtained.

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 charge to the surface of the photoreceptor; Developing means for generating an electrostatic latent image on the surface of the photoconductor by the charging means and the exposure means, and forming a colored toner image corresponding to the electrostatic latent image on the surface of the photoconductor. Image forming apparatus comprising: a transfer unit for transferring a colored toner image onto a transfer material; a cleaning unit for removing residual toner on the surface of the photoconductor after the transfer; and a charge removing unit for removing a residual electrostatic latent image after the transfer. A plurality of elements are arranged, and a photoreceptor mounted on an image forming element for forming a black toner image includes an a-Si photoconductive layer and an a-SiC surface layer having a dynamic indentation hardness of 45 to 220 kgf / mm ^2. Are sequentially laminated The photoconductors mounted on the image forming elements for forming a colored toner image other than the black toner image are formed by OPC in the layer structure, and the process speed of each photoconductor is set to 200 mm / sec or more. I do.

[0010]

DETAILED DESCRIPTION OF THE INVENTION diagram 2 of the photosensitive member is a layer structure of the photosensitive member 1 according to the image forming element for forming a black toner image of the present invention, the vacuum photosensitive layer 3 on the substrate 2 of the conductive A film is formed by an evaporation method, an active reaction evaporation 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 CVD method, a plasma CVD method, or the like. The photosensitive layer 3 includes, for example, a carrier injection blocking layer 4, a photoconductive layer 5, a-Si
And a surface layer 6 made of SiC.

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-Si, a
-Formed by SiC, amorphous silicon nitride or the like.

The photoconductive layer 5 is made of a-Si (however, a-SiC in which carbon is added to a-Si may be used). When the thickness of the photoconductive layer 5 is set to 30 μm or more, the charging ability of the OPC photoconductor can be considerably approximated.
Further, the thickness is 30 to 100 μm, preferably 30 to 100 μm.
The thickness is preferably 70 μm. When the thickness is less than 30 μm, the charging ability tends to decrease, and when it exceeds 100 μm, the residual potential tends to increase.

The surface layer 6 is also made of highly insulating a-SiC and has a dynamic indentation hardness of 45 to 220 kgf /
The composition of the components is determined so as to obtain mm ² . This dynamic indentation hardness is determined by each gas flow ratio of CH ₄ and SiH ₄ in film formation, high frequency power, and the like.
If it is less than 45 kgf / mm ^2, at the time of image acquisition, image deterioration caused by scratches occurred on the surface of the photoreceptor, on the other hand, if it exceeds 220 kgf / mm ^2, hardly shaved photoconductor surface, the oxide Insufficient removal results in image deletion.

Thus, in the photosensitive member mounted on the image forming element for forming a black toner image, the a-Si
Photoconductive layer and dynamic indentation hardness of 45 to 220 kgf / m
By adopting a layer configuration in which the a-SiC surface layer having m ² was sequentially laminated, image deletion and image deterioration did not occur, and as a result, the photoconductor 1 for high-speed color printing was 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 transport belt 19 and is moved in the direction of the arrow.

Thus, according to the image forming apparatus 18 having the above-described configuration, it is possible to provide a color image forming apparatus which does not cause image deletion and image deterioration, does not cause printing unevenness, and can obtain a clear color image. 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.

According to the present invention, the supply current of the charging means to the photosensitive member mounted on the image forming element for forming a black toner image is made smaller than the supply current of the charging means in the image forming apparatus having the OPC photosensitive member. , 1.05 to 2.50
If the height is twice as high, the charging of the conventionally known OPC photoconductor can be considerably approximated (for example, about 800 V), that is, the charging difference can be 200 V or less as compared with the OPC photoconductor. In addition, high-speed color printing can be performed more advantageously, the variation in the characteristics of the respective photoconductors is reduced, and the dark attenuation characteristics are also reduced. The black toner image forming photoconductor 1 having such a configuration can be applied to both positive and negative charging.

[0021]

【Example】

(Example 1) Photoconductor of image forming element 7a (K) (external dimensions:
(φ180mm, length 372mm)
Plasma C on a cylindrical substrate made of 9.9% Al
The photosensitive layer 3 of FIG. 2 was formed by the VD method under the film forming conditions shown in Table 1.

[0022]

[Table 1]

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 dynamic indentation hardness of the a-SiC surface layer constituting the photoreceptor of the image forming element 7a (K) was measured using an ultra-micro hardness tester manufactured by Shimadzu Corporation.
/ Mm ² .

When the process speed of each photoconductor is set to 210 mm / sec in the image forming apparatus 18 shown in FIG. 1 equipped with each of the photoconductors, image deletion and image deterioration do not occur, and printing unevenness occurs. It disappeared and a clear color image was obtained.

This image flow is 33,000 after printing for 30,000 sheets.
The image was left standing for 8 hours in an environment of 85 ° C. and 85%, and then judged based on the first image, and the image deterioration was further examined by the presence or absence of scratches and the like on the 30,000 sheets after printing. .

(Example 2) Image forming element 7a of (Example 1)
In the photoconductor of (K), the dynamic indentation hardness of the a-SiC surface layer was changed in various ways, and the other conditions were the same. The result as shown in FIG. These results were printed on 300,000 sheets, respectively, and were marked with Δ when no image blurring (print blur) occurred and with x when print blur occurred. Regarding the image quality, a symbol “〇” indicates that no scratches or the like occurred, and a symbol “X” indicates that the scratches occurred.

[0028]

[Table 2]

As is clear from this table, if the dynamic indentation hardness is in the range of 45 to 220 kgf / mm ² ,
Both image deletion and image quality were good.

(Example 3) Next, the inventor of the present invention has set the a-SiC in the photosensitive member of the image forming element 7a (K) of (Example 1).
When the dynamic indentation hardness of the surface layer and the process speed of each photoconductor were changed in various ways, and the other conditions were the same, the image deletion and image deterioration were measured in the same manner. The result was obtained.

[0031]

[Table 3]

According to the table, the dynamic indentation hardness is 45 to 22.
It can be seen that when the process speed was set to 200 mm / sec or more within the range of 0 kgf / mm ² , both the image deletion and the image quality were improved.

(Example 4) Dynamic indentation hardness is 100 kgf
/ Mm ² , and further increase the process speed by 300
In the image forming apparatus of mm / sec, the printing was evaluated by changing the supply current, and the results shown in Table 4 were obtained.

This print evaluation is divided into two. The mark Δ indicates that a good print was obtained, and the mark X indicates a poor case.

[0035]

[Table 4]

As is clear from the table, the applied voltage ratio (a
-Si / OPC) of 1.05 to 2.50, excellent printing was obtained. However, the test No. A for 8
-The supply current at the Si photoreceptor was too large, causing discharge breakdown and black spots.

In the test No. of the present invention, No. 3 to Test No. 3
7, the charging of the photoconductor 1 of the image forming element 7a (K) is -620V to -770V, the charging of the OPC photoconductor is -800V, and the charging difference between the two is 180V to
It was 30V.

When color printing was performed using the image forming apparatus of the present invention as described above, an excellent color image was obtained at a printing speed of 12 sheets / min. 200m more
At a process speed of m / sec or more, high-speed color printing was more remarkably performed, the variation in the characteristics of the respective photoconductors was reduced, and the dark decay characteristics were also reduced. As a result, the printing performance was further improved.

[0039]

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 has a dynamic indentation hardness of 4 with the a-Si photoconductive layer.
A-SiC surface layer of 5 to 220 kgf / mm ² is sequentially laminated, and a photoreceptor mounted on an image forming element for forming a colored toner image other than a black toner image is formed by OPC; By increasing the process speed of each photoreceptor to 200 mm / sec or more, image deletion and image degradation do not occur, variations in the characteristics of each photoreceptor are reduced, and dark decay characteristics are also reduced. Has been further improved, and as a result, it has become sufficiently practical as a color printer for high-speed color printing.

Further, in the present invention, the photosensitive member mounted on the image forming element for forming a black toner image is constituted by an a-Si photoconductive layer, and the voltage applied to the charging means is reduced by
In order to form a colored toner image other than a black toner image, the voltage applied to the charging means in the image forming element on which the OPC photoreceptor is mounted is 1.05 to 2.50 times higher than the applied voltage. A high-performance color printer could be provided.

Further, according to the present invention, by increasing the durability against monochrome printing, it is possible to sufficiently use it for color printing, and to obtain a long-term reliable image capable of maintaining the overall printing performance for a long time. 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 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 Conveying belt

Claims (1)

[Claims] 1. A photoconductor, a charging means for applying a charge to the surface of the photoconductor, and an exposing means for irradiating a charged area of the photoconductor with light, wherein the charging means and the exposing means cause the photoconductor to be charged. Developing means for generating an electrostatic latent image on the surface of the photosensitive member, 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 transfer-receiving material; An image forming 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, and an image for forming a black toner image the photoreceptor is mounted on the forming element to sequentially stacked layer structure and the amorphous silicon carbide surface layer amorphous silicon photoconductive layer and the dynamic indentation hardness is 45~220kgf / mm ² is black toner The photoreceptor is mounted on the image forming element to form a colored toner image other than constituted by OPC,
An image forming apparatus in which the process speed of each photoconductor is 200 mm / sec or more.