JPH10268539A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deposition or sticking of a toner during cleaning and to form a good image by constituting the photosensitive layer surface of amorphous silicon carbide and specifying the adhesion strength to a toner and the average particle size of the toner used for a developing means. SOLUTION: In a photoreceptor 1, a photosensitive layer 3 consisting of amorphous silicon (a-Si) is formed on a conductive substrate 2 by vacuum evaporation method, activated reaction evaporation method, ion plating method, RF sputtering, method, DC sputtering method, DC magnetron sputtering method, thermal CVD method, etc. The photosensitive layer 3 is formed by successively depositing a carrier injection preventing layer 4, photoconductive layer 5 and surface protective layer 6. The adhesion strength of the photosensitive layer 3 (surface protective layer 6) to a toner is controlled to <=93 mN/m. Moreover, a toner having <10 μm average particle size is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus equipped with a photosensitive member having a photosensitive layer of amorphous silicon.

[0002]

2. Description of the Related Art A photosensitive member having a photosensitive layer made of amorphous silicon (hereinafter, amorphous silicon is abbreviated as a-Si) has already been commercialized, but this a-Si photosensitive member has a drum shape made of aluminum metal. The outer peripheral surface of the substrate is mirror-finished with a surface roughness of about 0.1 S by cutting or the like, and then the a-Si photosensitive layer is formed to a thickness of 10 μm to 50 μm or to about 80 μm by CVD or PVD. Obtained by forming.

Prior to film formation on the aluminum metal drum,
By performing mirror finishing as described above, the surface of the photosensitive layer formed as a film on the substrate is made as smooth as possible,
The number of defects is minimized, thereby improving the image characteristics.

On the other hand, the electrophotography process for the a-Si photoreceptor includes the Carlson method and the like, and the process generally employs a cleaning means for removing residual toner on the photoreceptor surface. This cleaning means includes a blade method, a fur brush method, a magnet brush method, and the like. Regardless of which method is used, the toner is used to immediately remove the residual toner attached to the surface of the photosensitive layer. It is desirable from the viewpoint of good cleaning to reduce the adhesion between the photosensitive layer and the photosensitive layer.

[0005]

However, even in such an image forming apparatus equipped with an a-Si photoreceptor, if the image forming apparatus has been operated for a long time at normal temperature and low humidity, or in a conventional image forming apparatus, the average particle size is small. In contrast, when a toner having an average particle diameter smaller than that is used in order to obtain a high quality image,
It becomes easy to adhere or fuse to the surface of the Si photoreceptor, so that it is difficult to remove the toner in the cleaning process, and as a result, there is a problem that a black spot-like image defect occurs in a white background image.

In view of the above circumstances, the present inventor has made intensive studies. As a result, in particular, in order to prevent toner adhesion and fusing during cleaning, the surface of the photosensitive layer is not smoothed as in the prior art. On the contrary, it can be understood that the problem is solved by roughening the surface, and the degree of the roughness is related to the work of adhesion to the surface of the a-Si photosensitive layer.
It has been found that such a problem can be solved by setting it to 3 mN / m or less.

Accordingly, the present invention has been completed based on the above findings, and an object of the present invention is to provide an image forming apparatus which achieves satisfactory image formation by preventing toner adhesion and fusion during cleaning. Another object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image even when operated for a long time at normal temperature and low humidity or using a toner having an average particle diameter of less than 10 μm. . Still another object of the present invention is to find an evaluation criterion based on the diameter of a toner to be used, so that a highly reliable image forming apparatus capable of obtaining stable quality even when various toners of various diameters are used. Is to provide.

[0008]

According to the present invention, there is provided an image forming apparatus comprising: a photoreceptor having a photosensitive layer made of a-Si laminated on a substrate; a charging means for applying a charge to the surface of the photoreceptor; Exposure means for irradiating the charged area with light; developing means for forming a toner image on the surface of the photoconductor with respect to the electrostatic latent image formed on the surface of the photoconductor by the charging means and exposure means; Transfer means for transferring the image to the transfer material, cleaning means for removing residual toner on the surface of the photoreceptor after transfer, and static elimination means for removing the residual electrostatic latent image after transfer are provided. The surface is made of amorphous silicon carbide (hereinafter, amorphous silicon carbide is abbreviated as a-SiC), and the adhesive work on the toner is made 93 mN / m or less, and the average of the toner used for the developing means is reduced. Characterized in that the diameter less than 10 [mu] m.

[0009]

Diagram 1 of the embodiment of the invention photoreceptor is a layer structure of the photosensitive member 1 according to the embodiment of the invention,
A photosensitive layer 3 made of a-Si is formed on a conductive substrate 2 by vacuum deposition, active reactive deposition, ion plating, R
A film is formed by an F 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 is formed by sequentially laminating a carrier injection blocking layer 4, a photoconductive layer 5, and a surface protective layer 6, for example.

On the substrate 2, copper, brass, SUS, Al,
Examples include a metal conductor such as Ni, or an insulator such as glass or ceramic whose surface is coated with a conductive thin film. The substrate 2 may be a sheet-shaped, belt-shaped or web-shaped flexible conductive sheet.
Transparent conductive materials such as metals such as Al, Ni or tin oxide, indium tin oxide (ITO) or the like on a metal sheet such as US, Al, Ni, or a polymer resin film such as polyester, nylon, or polyimide; An organic conductive material coated by vapor deposition or the like and subjected to a conductive treatment is used.

According to the present invention, the adhesive work of the photosensitive layer 3 (surface protective layer 6) with respect to the toner is set to 93 mN / m or less. That is, in the case of a conventional photoreceptor, since the substrate surface is mirror-finished with a surface roughness of about 0.1 S, the surface of the photosensitive layer also has the same surface roughness, thereby exceeding 93 mN / m. In contrast, according to the photoreceptor 1 of the present invention, the bonding work is performed.
By making the surface of the photosensitive layer 3 rough, the bonding work is 93 mN / m
In the following, preferably, the pressure was adjusted to 85 mN / m or less, and a good image was obtained as before, and toner adhesion / fusion was prevented during cleaning.

[0012] And for such an adhesive work,
The surface free energy and the toner diameter are parameters, and the material of the surface protective layer 6 and the toner are also parameters. The degree of achievement of toner adhesion / fusion during cleaning can be determined by the integrated work value of these parameters. It can be evaluated. Therefore, the value of the adhesive work is used as an evaluation criterion without depending on the material and diameter of the toner used, and stable quality can be obtained even when various toners of various diameters are used based on this criterion. .

The surface free energy can be expressed numerically by a dispersive force component, a polar force component, and a hydrogen bond force component, or a dispersive force component and a hydrogen bond force component. Thus, the sum of these values is defined as the surface free energy.

The bonding work and surface free energy are
Although it fluctuates depending on the material and type of the cutting tool and the conditions such as the number of revolutions and the feed rate at the time of cutting, in the present invention, by repeating various experiments, the optimum conditions of the cutting tool and the cutting conditions are determined. Once found, the surface of the photosensitive layer 3 can be roughened by such cutting to provide a suitable range of bonding work. Further, in addition to the above cutting means, a high-hardness metal ball may be hit over the entire outer peripheral surface of the substrate by using a rotary ball mill.

The work of adhesion is also related to the surface roughness of the photosensitive layer 3. Generally, as the work of adhesion becomes smaller, the surface roughness of the photosensitive layer 3 tends to become larger. The surface roughness of the layer 3 may be variously regular or irregular, and the surface roughness may be in the range of 0.8 μm to 6.0 μm, preferably 2.0 μm to 6.0 μm. I learned. However, even if the surface roughness range is set in this way, the required bonding work cannot be obtained.If the surface roughness is the same value but the surface unevenness is different, the bonding is performed accordingly. Work is also different. Thus, according to the photoreceptor 1 of the present invention, by setting the work of adhesion of the photosensitive layer 3 to the toner to 93 mN / m or less, it is possible to obtain a good image as before and to prevent toner adhesion / fusion during cleaning. Was.

[0016] Configuration FIG. 2 of the image forming apparatus is a printer configuration of the image forming apparatus 7 provided with a photosensitive member of the present invention, 8 denotes a photosensitive member, corona charging a charging means on the peripheral surface of the photoreceptor 8 Device 9 and an exposure device 10 (LED head) as an exposure means for irradiating light after charging.
A developing device 12 having a toner 11 for forming a toner image on the surface of the photoreceptor 8, and a transfer device 14 serving as a transfer device for transferring the toner image to a transfer material 13.
And a cleaning means 15 for removing the residual toner on the surface of the photoreceptor after the transfer, and a charge removing means 16 for removing the residual electrostatic latent image after the transfer. Also, 1
Reference numeral 7 denotes a fixing device for fixing the toner image transferred to the transfer material 13 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 black 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 apparatus 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 unit 10, the image forming apparatus 7 has a copier configuration.

The image forming apparatus 7 employs ordinary dry development, but is also applicable to a liquid developer used for wet development. Incidentally, the average particle size of the pigment of this liquid developer is extremely small, about 1 μm.

Thus, according to the image forming apparatus 7 of the present invention, when the average particle diameter is 10 to 20 μm as in the related art, even if the toner is operated for a long time at normal temperature and low humidity, the toner is kept in the cleaning step. -No adhesion or fusion to the surface of the Si photoreceptor. Further, even when a toner having an average particle diameter of less than 10 μm was used to obtain a high quality image, the toner did not adhere or fuse to the surface of the a-Si photosensitive member.

[0020]

EXAMPLE A photosensitive layer 3 is formed by a plasma CVD method on a cylindrical substrate made of Al having a purity of 99.9%. This photosensitive layer 3 contains 1500 ppm of boron and 1.
A-Si carrier injection blocking layer 4 containing 0% and 0.7% nitrogen, a-Si photoconductive layer 5 containing 0.5 ppm boron, a
And a surface protective layer 6 made of SiC.

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.

The contact work and surface free energy of the various photoconductors obtained by various polishing means were measured, and the results shown in Table 1 were obtained.

[0023]

[Table 1]

The contact work was measured using a CA-X roll-type contact angle meter manufactured by Kyowa Interface Science Co., Ltd. and surface free energy analysis software EG-11.

The measurement of the surface free energy is generally used in Japan, and is analyzed by applying a three-component method presented by the Adhesion Society, so-called extended Fowkes theory. Of the liquid (the values of the surface free energies of the dispersive force component, the dipole component, and the hydrogen bonding component are already known, for example,
The contact angle is measured by a droplet method using methylene iodide and the like, and is calculated based on the extended Fowkes theory based on the data.

Next, various photosensitive members are transferred to the image forming apparatus 7.
(Dry development: toner average particle diameter 8 μm), an image was formed by the Carlson method, a running test of 300,000 sheets was performed, and the image characteristics and toner adhesion were measured. The results shown in Table 1 were obtained. Was. ○ and △ for image characteristics
The mark was evaluated with a mark and the mark x, and the mark ○ indicates that a good white background image was obtained, and the mark △ indicates slight black spot or black streak image defects in the white background image, but there was no practical problem. The mark “x” indicates that black spots or black streak-like image defects were noticeably generated in the white background image.

In the above embodiment, at room temperature and normal humidity (23 ± 3
Image forming apparatus 7 having an average toner particle size of 8 μm at 50 ° C., 50 ± 10%). In addition, the average toner particle size at normal temperature and low humidity (23 ± 3 ° C., 15% or less) 8 μm
When the same experiment was performed using the image forming apparatus 7 described above, the same image characteristic was obtained for each sample.

[0028]

As described above, according to the image forming apparatus of the present invention, the surface of the photosensitive layer is made of a-SiC, and the work of adhesion of the photosensitive layer to the toner is set to 93 mN / m or less. A good image formation can be obtained by preventing toner adhesion and fusing at the time of printing. Particularly, even if the toner is operated for a long time at normal temperature and low humidity or a toner having an average particle diameter of less than 10 μm is used, a good image is formed. Formation was obtained.

Further, according to the present invention, since an evaluation criterion based on the diameter of the toner to be used has been found, a highly reliable image can be obtained with stable quality even when various toners of various diameters are used. An object of the present invention is to provide a forming apparatus.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a layer configuration of a photoreceptor according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an image forming apparatus 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 Image forming apparatus 9 Corona charger 10 Exposure device 11 Toner 12 Developing machine 13 Transfer material 14 Transfer device 15 Cleaning means 16 Static elimination means

Claims (1)

[Claims] A photosensitive member having a photosensitive layer made of amorphous silicon laminated on a substrate; a charging unit for applying a charge to a surface of the photosensitive member; an exposure unit for irradiating a charged area of the photosensitive member with light; Developing means for forming a toner image on the surface of the photoreceptor with respect to the electrostatic latent image formed on the photoreceptor surface by these charging means and exposure means; transfer means for transferring the toner image to a material to be transferred; Cleaning means for removing residual toner on the photoreceptor surface after the transfer, and static elimination means for removing the residual electrostatic latent image after the transfer are provided, and the surface of the photosensitive layer is made of amorphous silicon carbide,
An image forming apparatus characterized in that the work of adhesion to the toner is 93 mN / m or less, and the average particle size of the toner used in the developing means is less than 10 μm.