JPH11133645A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent image blurring even after printing of many sheets and to improve image quality by executing printing while controlling polishing in such a manner that the surface of a photoreceptor is smoothed and specifying the surface roughness Rz of a photoreceptor drum to <=500 angstrom and to maintain a sufficient polishing effect without damaging the photoreceptor drum and to prevent the image blurring without degrading image quality by controlled the polishing speed of the photosensitive drum. SOLUTION: This image forming device uses the electrophotographic photoreceptor formed by sequentially laminating a photoconductive layer and a surface layer consisting of a-SiC:H on a conductive substrate and has means for polishing the photoreceptor to the surface roughness Rz of <=500 angstrom. The extreme surface of the electrophotographic photoreceptor of the image forming device is polished at a polishing speed of 10 to 100 angstrom/10,000 times simultaneously with printing of the image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus using a photosensitive drum having a surface layer made of a-SiC: H.
The present invention relates to an image forming apparatus in which an i (amorphous silicon) -based photoconductor drum is appropriately used to prevent an image flow occurring at the time of image formation.

[0002]

2. Description of the Related Art In an electrophotographic method, a photosensitive member is charged.
Image formation is performed as a series of processes of forming an electrostatic latent image by image exposure → forming a toner image by development → transfer → fixing.When a discharge for charging is performed in a charging process, ozone is generated by this discharge. Occur. Then, the components in the air are decomposed by the generated ozone to produce water-soluble ion products such as Nox and SOx, and the ion products adhere to the Si-based photosensitive drum, and further take in moisture in the atmosphere. A composite product is produced to lower the surface resistance of the photosensitive drum. This causes a lateral flow of potential at the edge of the electrostatic latent image drawn on the surface of the photosensitive drum,
As a result, image deletion occurs and the print quality is degraded. Conventionally, a heater is installed inside the photoconductor drum and heated,
A technique of giving energy for desorbing moisture taken in by ion products on the surface of a photoreceptor and suppressing a decrease in resistance of the photoreceptor drum in a high-humidity environment is known and has already been generalized. In addition, a polishing system consisting of a toner mixed with an abrasive and an elastic roller, or another polishing system polishes and removes ion products adhering to the photosensitive drum, causing a reduction in resistance of the surface of the photosensitive drum. Techniques for removing the substance itself are also known.

[0003]

However, the measures against image deletion described above have not always been satisfactory. That is, the above-described heating method using a heater has a problem in that energy is wasted because a heater must be used at all times. Further, the temperature of the heater cannot be sufficiently increased in order to prevent the melting of the toner that comes into contact with or adheres to the photoconductor, and a complete measure against image deletion cannot be taken. On the other hand, the method of polishing the photoreceptor surface includes a
-Since the surface layer of the Si-based photosensitive drum is hard and difficult to polish, there is a problem that polishing takes time and the like, and further improvement has been awaited. Accordingly, an object of the present invention is to improve image quality by preventing the occurrence of image deletion after printing a large number of sheets, and at the same time, it is not possible to reduce the temperature of the heater used or to delete the heater itself. It is. It is a further object of the present invention to prevent image flow, prevent image quality from deteriorating over a long period of time, and extend the life of the photoconductor and thus the image forming apparatus.

[0004]

As described above, the generation of the image flow is caused by the ion product generated from the ozone generated by the discharge of the charger adhering to the photosensitive drum. Since the ion product enters into the roughness structure of about 0.1 μm on the surface of the photosensitive drum, it cannot be sufficiently removed by the conventional polishing system. For example, the surface roughness of a conventional photosensitive drum provided with a surface layer made of a-SiC: H is about Rz = 800 angstroms. When a large number of prints are made on this photoreceptor drum without any special control using a conventional general toner containing an abrasive and an elastic roller, the surface is polished by the photoreceptor surface, toner, transfer paper, etc. The roughness is about 600 angstroms.

[0005] However, at this level of surface roughness, ion products attached to the surface of the photoreceptor are not completely removed, and image flow occurs. Regarding this point, it was confirmed that when the photosensitive drum after printing a large number of sheets was wiped with water, the image flow was improved, and the cause was that the ion product remained on the photosensitive member surface. Therefore, in the present invention, the removal of ion products is facilitated by smoothly polishing the surface of the photoreceptor for each printing process throughout printing of a large number of sheets. More specifically, in the present invention, an image forming apparatus having a polishing means for polishing the surface of the photoreceptor to a roughness of Rz = 500 angstroms or less is used, and a conventional photoreceptor drum, particularly an a-Si type photoreceptor drum, is used. By lowering the hardness of the surface layer, quick polishing by a general polishing means was enabled, and the image flow was improved. Further, while sufficiently maintaining the polishing effect of the photoconductor drum, the polishing speed is set so as not to damage the photoconductor, thereby suppressing the image flow without deteriorating the image quality. The adjustment of the hardness of the surface layer of the photoreceptor is performed, for example, by adjusting the C of a-SiC: H constituting the surface layer.
It can be performed by adjusting the composition ratio of Si and Si.

That is, the image forming apparatus of the present invention uses a drum-shaped electrophotographic photosensitive member in which a photoconductive layer and a surface layer made of a-SiC: H are sequentially laminated on a conductive substrate,
An image forming apparatus having means for polishing the surface roughness Rz of the photoreceptor to 500 angstrom or less, wherein the outermost surface layer of the electrophotographic photoreceptor is simultaneously coated with an image by 10 to 1
It is characterized in that it is polished at a polishing rate of 00 angstroms / 10,000 rotations.

[0007]

FIG. 1 is a basic structural diagram showing a process system of an image forming apparatus according to the present invention, particularly around a photoconductor 11 of a printer. Around the photoreceptor 11, a charger 13, an exposure source 15, a developing roller 1
7, a transfer roller 19, a polishing roller 21, a cleaning blade 27, and a static eliminator 29 are provided. The photoconductor 11 is discharged in the dark by the charger 13, and the entire surface of the photoconductor 11 is uniformly charged. Next, the exposure source 15
, An image signal is exposed, electric charges are selectively leaked, and an electrostatic latent image is formed.

Next, the electrostatic latent image is developed with a developer by a developing roller 17 to form a visible image on the photoreceptor 11 by toner. The toner on the photoconductor 11 is transferred to the transfer paper 31 by the transfer roller 19, and the transferred image is fixed by a fixing device (not shown), thereby completing the image formation. On the other hand, toner (remaining toner) remaining on the photoconductor 11 without being transferred in the transfer process is removed by the polishing roller 21 and the cleaning blade 27, and is conveyed by the toner collecting screw 25 to a waste bottle (not shown). The photosensitive member 11 is neutralized by the neutralizer 29, returns to the initial state, and repeats the image forming process after the charging step. As described above, when the image forming process is repeated, that is, when a large number of sheets are continuously printed,
Ozone is generated by the discharge of the photoconductor 11, and as a result, ion products adhere to the surface of the photoconductor 11, resulting in a decrease in the surface resistance of the photoconductor 11 and a deterioration in image quality due to image deletion.

Therefore, the present invention uses an image forming apparatus having a polishing means for polishing the surface roughness Rz of the photoreceptor 11 to 500 angstroms or less. The average roughness Rz is
This is a 10-point average roughness of 100 μm length according to JIS B0601. Polishing can be performed by various members that come into contact with the photoconductor 11, and the polishing roller 21 and the cleaning blade 27 correspond to these. Further, by blending the abrasive with the toner in the developer, the polishing at the time of contact with the contact member is further promoted. In particular, in the present invention, by using a photoreceptor having a surface layer having a specific small hardness as the photoreceptor 11, the photoreceptor 11 is polished for each printing process by short-time processing using a general polishing means, so Realizing and maintaining a smooth photoreceptor surface,
In addition, ion products can be removed.

As the polishing roller 21, for example, an elastic roller can be used. The elastic roller is pressed against the photoconductor 11 by the urging force of the spring 23 to polish the surface of the photoconductor 11. The degree of polishing can be controlled by setting the hardness and linear pressure of the polishing roller 21 and the peripheral speed with the photoconductor 11. As the abrasive, titanium oxide, alumina, silica and the like can be blended in the developer.

As the photoconductor 11, for example, as shown in FIG. 2, a carrier injection blocking layer 43, a photoconductive layer 45, and a surface layer 47 made of a-SiC: H are formed on a conductive substrate 41. Those laminated sequentially are used. Conductive substrate 4
For example, a conductor or an insulator subjected to a conductive treatment is used for Al. Ni, Fe, C
Metals such as u and Au are mainly used.

The photoconductive layer 45 is made of Se, Se-T
e, Se alloys such as As ₂ Se ₃ , ZnO, CdS, CdS
e-dispersion type inorganic photoreceptor in which particles of a II-VI compound such as e are dispersed in a resin, an organic semiconductor material such as polyvinyl carbazole, or a-Si is used.
An i (amorphous silicon) based photoreceptor is preferable. The configuration of the photoconductive layer is not particularly limited, and may be a single layer type or a stacked type of a charge generation layer and a charge transport layer. Further, a carrier injection blocking layer 43 for preventing adhesion between the conductive substrate 41 and the photoconductive layer 45 and preventing charge injection may be provided.

As the surface layer a-SiC: H, a layer having appropriate polishing characteristics or hardness is used. Specifically, at the same time as printing an image, 10 to 100 angstroms per 10,000 rotations of the drum-shaped photoconductor, preferably 1
A surface layer and a polishing means capable of realizing a polishing rate of 0 to 30 angstroms are used. A-SiC: H which satisfies such polishing characteristics is, for example, a-SiC: H which is a surface layer.
It can be obtained by controlling the element ratio between C and Si in the C: H layer. Specifically, the surface layer a-SiC: H
When represented by the element ratio of the following chemical formula 2, X is 0.1.
It is desirable to use those in the range of 95 ≦ X <1.0.

[0014]

Embedded image

A-Si having a C / Si ratio in the above range
The C: H layer has an appropriate hardness, and provides the polishing characteristics and the effect of removing ion products of the present invention. Note that a-Si
C: H indicates hydrogenated amorphous silicon carbide. The polishing rate of the surface layer depends on the polishing characteristics of the surface layer.
It can be adjusted by controlling the polishing means.
By adjusting the urging force of the spring 23, the pressing pressure of the polishing roller can be controlled and controlled. Also,
Fine adjustment can be made by the amount of abrasive added to the toner and the balance of other peripheral devices. As described above, by setting the polishing rate so as not to damage the photoconductor drum while sufficiently maintaining the polishing effect of the photoconductor drum, it is possible to suppress the image flow without deteriorating the image quality.

[0016]

According to the present invention, printing is performed while controlling the polishing so that the surface of the photoreceptor becomes smooth, and the surface roughness Rz of the photoreceptor drum is set to 500 angstroms or less, thereby printing a large number of sheets. The image quality can be improved by preventing the image flow later. Further, by controlling the polishing speed of the photoconductor drum, a sufficient polishing effect can be maintained without damaging the photoconductor drum, and image flow can be prevented without deteriorating image quality.
Further, as a result, a good image can be obtained even if the heater temperature is lowered or the heater itself is omitted, and energy saving and long life can be achieved. At the same time, the effect of shortening the warm time can be obtained.

[0017]

【Example】

Example 1 As shown in FIG. 2, a film was formed on an aluminum substrate by plasma CVD under the film forming conditions shown in Tables 1 and 2.
Carrier injection blocking layer made of Si: H: B: N, a-S
A photoconductive layer made of i: H and a surface layer made of a-SiC: H are formed to form a-Si photosensitive drums A and B.
It was created. As shown in Table 1, these drums A and B have an injection blocking layer and a photoconductive layer having a common composition. on the other hand,
As shown in Table 2, the C / Si composition ratio of the surface layer is different for each of the photoconductors A and B. The prepared photoreceptor had a drum shape with a diameter of 30 mm and a width of 254 mm. Table 3 shows the physical property values of the obtained photoreceptor. XPS for measuring chemical composition
A surface analyzer (X-ray electron spectrometer) was used, and an ultra-fine hardness meter (DUH-201 manufactured by Shimadzu Corporation) was used for hardness measurement.

Using this a-Si photosensitive drum, FIG.
4% printing on A4 paper was performed by the reversal development method using the apparatus shown in FIG. Here, a polishing system was provided in which TiO ₂ was mixed into the toner as an abrasive, and the photoreceptor surface was polished by a polishing roller made of urethane foam. The drum heater was not used. Table 4 shows the evaluation results of image flow (flow) and image quality until after printing of 30,000 sheets. The image flow is H.
H. Confirmation was carried out with an image after leaving for 8 hours in an environment (30 ° C.-80% RH). The image flow was determined for each rank, and 1 was set to a good side, 5 was set to a bad side, and the practical level was set to 1.5 or more.
The image quality was evaluated by a three-step evaluation (（, Δ, ×) as an evaluation of image defects other than image deletion. The surface roughness of the photoreceptor drum after printing was determined to be 100 by an atomic force microscope (AFM).
The 10-point average roughness (Rz) at a length of μm was determined.

[0019]

[Table 1] Table 1: Drum film formation conditions 1 layer type Injection blocking layer Photoconductive layer gas flow rate * ¹ SiH ₄ (sccm) 130 300 B ₂ H ₆ (sccm) * ² 0.16% 0.7ppm NO (sccm) * ² 10.0% -Gas pressure (Torr) 0.43 0.45 Substrate temperature (° C) 290 290 High frequency power (W) * ¹ 133 300 Film thickness (μm) 2.5 15.0 Film formation rate (μm / Hr) 2.5 5.0 * 1) The values of gas flow rate and high frequency power represent one chamber. * 2) The numerical value indicates the doping amount

[0020]

[Table 2] Table 2: Drum film formation condition 2 (surface layer) Type of photoconductor A Type of B layer Photoconductive layer side Free surface side gas flow rate * ¹ CH ₄ (sccm) 208 167 208 SiH ₄ (sccm) * ² 2.5% 8.3% 0.4% Gas pressure (Torr) 0.35 Substrate temperature (° C) 290 High frequency power (W) * ¹ 133 Film thickness (μm) 0.85 * 1) The values of the gas flow rate and the high frequency power represent one chamber. * 2) Numerical values indicate the ratio (%) to CH ₄ .

[0021]

[Table 3] Table 3: Drum physical properties Type of photoreceptor Type of all drums A and B layers Interface Free surface Free surface composition (C / Si + C) × 100 (%) 50 80 97 Hardness Kgf / mm ² 420 800 100 Surface roughness (angstrom)-900 830

[0022]

[Table 4]Table 4: Evaluation result of image deletion and image quality after printing 30,000 sheets Photoconductor type A B Polishing speed * Ten 30 Three Ten 30 100 130 Ryu flow Ryu flow Ryu flow Ryu flow Ryu flow Ryu flowNumber of printed sheets Quality Quality Quality Quality Quality Quality Quality Quality Initial 1.0 ○ 1.0 ○ 1.0 ○ 1.0 ○ 1.0 ○ 1.0 ○ 1.0 ○ 5000 2.5 × 1.5 △ 2.0 △ 1.5 ○ 1.5 ○ 1.5 ○ 1.5 △ 10000 4.5-1.5 × 4.0 △ 1.0 ○ 1.0 ○ 1.0 ○ 1.0 × 15000 5.0 − 2.0 × 5.0 − 1.0 ○ 1.0 ○ 1.0 ○ 1.0 × 20000 5.0 − 2.0 × 5.0 − 1.0 ○ 1.0 ○ 1.0 ○ 1.0 × 25000 5.0 − 2.0 × 5.0 − 1.0 ○ 1.0 ○ 1.0 ○ 1.0 × 30000 5.0 − 2.5 × 5.0 − 1.0 ○ 1.0 ○ 1.0 ○ 1.0 × 300000 sheets − − − − − − − − − − 1.0 ○ − − *) Polishing rate unit: Angstrom / 10,000 rotations

The image forming apparatus of the present invention softens the surface hardness of the photoreceptor and controls the polishing rate,
The effect of removing ion products by polishing and the effect of making the surface roughness of the photoreceptor drum smooth immediately after printing can be obtained, thereby improving the effect of making ion products less likely to adhere. As a result, Table 4 shows the results. As described above, an image forming system in which image deletion hardly occurs and in which a good image can be obtained for a long period of time has been realized. In the photoreceptor B of the present invention, the surface roughness rapidly becomes smooth at the start of printing, and the surface roughness becomes 500 angstroms or less after printing about 2,000 sheets,
After printing about 100,000 sheets, it almost drops to the final value,
Good printing characteristics were obtained stably even after printing 000 sheets.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a substrate around a photoreceptor in an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic view showing a layer structure in one embodiment of a photoreceptor used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Photoconductor 13 Charger 15 Exposure source 17 Developing roller 19 Transfer roller 21 Polishing roller 23 Spring 25 Toner collection screw 27 Cleaning plate 29 Static eliminator 31 Electrographic paper 41 Conductive substrate 43 Carrier injection prevention layer 45 Photoconductive layer 47 Surface layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Norio Tomie 704 Matabe, Noshino, Tamaki-cho, Tamaki-cho, Mie Prefecture 19 Inside the Mie Plant of Kyocera Corporation (72) Takayuki Sato, Inabashita-Matabei, Noshina, Tamaki-cho, Mie Pref. 704 19 Kyocera Corporation Mie Plant

Claims (2)

[Claims] 1. A photoconductive layer and a-Si on a conductive substrate.
A drum-shaped electrophotographic photosensitive member in which a surface layer made of C: H is sequentially laminated is used, and the surface roughness Rz of the photosensitive member is 500.
An image forming apparatus having means for polishing to less than Å, wherein the outermost surface layer of the electrophotographic photosensitive member is polished at a polishing rate of 10 to 100 Å / 10,000 rotations simultaneously with printing of an image. Image forming apparatus. 2. An element ratio of the outermost surface layer of the photoreceptor is
Formula (1) of The image forming apparatus according to claim 1, wherein X is in a range of 0.95 ≦ X <1.0.