JP2000162937A - Image forming device - Google Patents

Abstract

[PROBLEMS] Even when a photosensitive drum is polished with a polishing roller, jitter and the like are reduced, and polishing is insufficient even when a pattern having a low printing ratio is continuously printed without being affected by the printing pattern. To provide an image forming apparatus. An amorphous silicon photoreceptor, a developing means for forming a toner image with a polishing toner, a supply means for supplying a polishing toner, an elastic roller pressed against the surface of the photoreceptor, And polishing means 6 and 9 for polishing the surface of the photoreceptor 1 by rubbing the surface of the photoreceptor 1 and polishing the surface roughness of the photoreceptor to 500 ° or less. Elastic roller 6 pressed against 1
, The rotation of the elastic roller 6 is forcibly stopped during non-printing, and the surface is polished by sliding friction between the stopped elastic roller 6 and the rotating photosensitive member 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus using an amorphous silicon (hereinafter referred to as "a-Si") photosensitive drum, and particularly to an a-Si photosensitive drum capable of suppressing image deletion. It is related to the used method.

[0002]

2. Description of the Related Art It has been known that an image forming apparatus using an a-Si photosensitive drum is liable to cause image deletion due to its characteristics. That is, when charging is performed using a charger, ozone is generated by discharging the charger.
The components in the air are decomposed by this ozone, and NOx and S
An ion product such as Ox is generated. Since this ion product is water-soluble, it adheres to the photosensitive drum and enters into the roughness structure of about 0.1 μm on the surface of the photosensitive drum, so that it can be removed by a cleaning system used in a general-purpose machine. In addition, they take in moisture in the atmosphere, and the resistance of the surface of the photosensitive drum decreases. As a result, a lateral flow of potential occurs at an edge portion of the electrostatic latent image formed on the surface of the photoconductor drum, and as a result, image flow may occur.

Conventionally, a heater is provided in a photoconductor drum to give energy for releasing the moisture taken in by the ion product, thereby suppressing a reduction in the resistance of the photoconductor drum surface in a high-humidity environment. It has been generalized.

However, in such an apparatus, the number of components for constituting the heater is large, which not only increases the cost but also requires consideration of safety.
Therefore, prior to the filing of the present application, the present applicant has developed a system for polishing ozone by using a system in which a photoreceptor is polished by an interaction between a polishing toner mixed with a polishing agent and a polishing means (a polishing roller and a cleaning blade) without using a heater. A technique for removing an object was proposed (Japanese Patent Application No. 9-315984).

This technique is an image forming apparatus having a structure for polishing the surface roughness of an a-Si photosensitive drum so as to be less than Rz 500 ° (angstrom). Even if the substance adheres to the surface of the photosensitive drum, the ozone product can be sufficiently removed to polish the surface roughness to Rz 500 ° or less.

[0006]

However, in order to polish the photosensitive drum with the elastic roller, a large pressing force of the elastic roller against the photosensitive drum and a linear velocity difference of about 20% are required. Image defects occur due to uneven rotation of the elastic roller.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image forming apparatus capable of reducing jitter and the like and polishing a required amount of the surface of a photoreceptor even when the photoreceptor drum is polished by a polishing roller. The purpose is to do.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an amorphous silicon photoreceptor and an electrostatic latent image of the photoreceptor. Developing means for forming a toner image, supply means for supplying the polishing toner, and polishing means for pressing an elastic roller against the surface of the photoreceptor and rubbing the surface of the photoreceptor with the elastic roller. An image forming apparatus configured to print the toner image on a recording medium while polishing the surface roughness of the photoreceptor to 500 ° or less by an interaction between the polishing toner supplied by the supply unit and the polishing unit. In the apparatus, at the time of printing on the recording medium, the elastic roller pressed against the photoconductor performs driven rotation with the rotation of the photoconductor, while the rotation of the elastic roller is forcibly stopped during non-printing. To, and configured to polish the surface by rubbing of the photosensitive member and the rotating resilient roller that the stop.

In the normal continuous printing operation, the time from the formation of the electrostatic latent image on the photosensitive member to the formation of the next electrostatic latent image is a few seconds due to the paper passing speed. It is said to be the so-called paper space. Since an electrostatic latent image is formed on the photosensitive member and the elastic roller is driven to rotate relative to the photosensitive member during printing, problems such as jitter can be solved.
On the other hand, between papers on which no electrostatic latent image is formed on the surface of the photoconductor, the elastic roller is forcibly stopped by the clutch for about 0.1 second, and the surface is polished with a speed difference with respect to the rotating photoconductor. It is composed. The range that can be polished at one time is limited, but the entire surface of the photoreceptor is polished substantially uniformly while the printing operation is repeated.

[0010]

Embodiments of the present invention will be described below. The present invention relates to an electrophotographic apparatus using an a-Si photosensitive drum, wherein the surface roughness of the photosensitive drum is reduced to Rz5.
In order to provide an apparatus for polishing under 00 °, FIG.
FIG. 1 is an explanatory diagram of a schematic configuration of a printer to which the present invention has been applied. FIG. 2 is an explanatory view of a main part of the photosensitive drum and the polishing roller.

An exposure source 3, a developing roller 4 (developing means and supply means), a transfer roller 5, and a polishing roller 6 (polishing means) comprising an elastic roller are arranged along the rotation direction of the photosensitive drum 1.
A cleaning blade 9 (polishing means), a static eliminator 10 and a charger 2 are provided. As is well known, after the static elimination by the static eliminator 10, the exposure source 3 exposes the photoconductor 1 uniformly charged by the charger 2. The latent image is recorded, the exposed latent image is visualized into a toner image by the developing roller 4 by reversal development, and the toner image is transferred to the transfer paper 11 by the transfer roller 5.

The untransferred toner not transferred by the transfer roller 5 removes residual toner from the surface of the photosensitive drum 1 by a polishing roller 6 and a cleaning blade 9, and thereafter,
The removed residual toner is conveyed to a waste bottle (not shown) by a toner collecting device such as a collecting screw 8.

Reference numeral 14 denotes a cleaning device, which is a photosensitive member 1
And a cleaning blade 9, which is a polishing system for polishing the surface of the photoreceptor. The polishing roller 6 has a spring 7 for applying a constant pressure to the surface of the photoconductor. The configuration of the polishing roller 6 is covered with urethane foam rubber via a shaft. The rubber hardness is adjusted to 50 degrees via the shaft. As shown in FIG. 2, a clutch 12 for transmitting rotation from a power source (not shown) is provided at the shaft end of the polishing roller 6. In the non-transmission state, the photosensitive drum 1 is driven to rotate in accordance with the rotation of the photosensitive drum 1, and during non-printing (for example, between sheets in continuous printing), the polishing roller 6 is moved to about 0.1 by a clutch.
Force stop for about a second.

FIG. 4 shows the layer structure of the photosensitive drum 1, and FIG.
0 is a conductive substrate, 21 is a photoconductive layer, and 22 is a surface protective layer. The photoreceptor used in the present invention is different from the conventional photoreceptor in the surface protective layer 22. The surface protection layer 22 is made of a-Si
It is composed of C: H, and its element ratio is represented by a composition formula a-Si1-
X CX: When expressed as H, the value of X is 0.95 ≦ X <1.
00, preferably 0.96 ≦ X <0.98, and the dynamic indentation hardness of the surface is 45 to 300 kgf / mm.
2

By setting the value of X to 0.95 or more, the hardness is reduced and the surface is easily shaved, and a fresh surface is always produced by polishing with the polishing roller 6 together with the polishing toner. By making it less than the above, it becomes easy to make the dynamic indentation hardness 45 kgf / mm 2 or more.

The dynamic indentation hardness of the surface is 45 to 3
00 kgf / mm2, preferably 50 to 220 kgf /
mm2. As described above, since the hardness is set to 300 kgf / mm 2 or less as compared with the conventional a-SiC: H surface protective layer, the surface is appropriately polished by the interaction between the polishing toner and the polishing roller 6, and the photoreceptor is polished. The discharge products attached to the surface protection layer 22 of the drum 1 can be polished. On the other hand, by setting the hardness to 45 kgf / mm 2 or more, the amount of shaving by the polishing roller 6 does not become too large, and the life thereof does not become extremely short as compared with the conventional a-SiC: H. .

Such a dynamic indentation hardness is as follows:
This is an effective hardness evaluation method for evaluating the hardness of a thin film of 0 μm or less, a test load is applied to the surface of the thin film with a triangular pyramid indenter, and the indentation depth of the indenter at that time is measured.
This is the hardness that is determined by further calculation. In this measurement, an ultra-micro hardness tester DUH-201 manufactured by Shimadzu Corporation was used.

Further, instead of the surface protection layer 22, a-Si
C: H The hardness of the surface protective layer may be gradually reduced from the interface side with the photoconductive layer 21 toward the surface of the surface protective layer 22, and the other layer configurations may be the same. That is, when the configuration is made smaller in this way, the discharge products that have entered the concaves on the unevenness existing on the surface of the surface protective layer 22 at the initial stage of using the photosensitive drum 1 are removed. Irregularities can be removed by flattening, and by polishing with the polishing roller 6, the irregularities are gradually reduced to reduce irregularities, thereby easily removing products adsorbed on the surface. As the surface is abraded, the hardness of the surface is increased accordingly, and the amount of abrasion due to the polishing is reduced, thereby preventing the surface from being damaged. As the surface is scraped in this way, the surface roughness of the photoreceptor becomes 500
Å Polished below. The photoreceptor used in the present invention is a special photoreceptor having a structure capable of shaving the surface as described above, but is not limited thereto.

Next, the operation of the present invention will be described. During the normal printing operation, printing is performed in a state where the driving force to the polishing roller 6 is cut off by the clutch 12, and the polishing roller 6 is driven to rotate with respect to the photosensitive drum 1. Therefore, the untransferred toner is cleaned by the cleaning blade 9 and is conveyed to the toner collecting roller 8 side.

The non-printing time of the present invention is defined as (1) from the time after the formation of the electrostatic latent image on the surface of the photoreceptor to the time when the printed paper is completely discharged and the photoreceptor stops. (2) At the time of machine startup and during idle rotation in which an electrostatic latent image of the photoconductor is not formed by providing a different mode (refresh mode) different from the normal printing operation performed every 10,000 sheets of printing (3) This is the time between papers between printings, and the polishing roller 6 pressed against the photoconductor 1 by the spring 12 by the clutch 12 is forcibly stopped for a predetermined time. In addition, in the case of the paper interval time of (3), 0.
It is configured to forcibly stop for about one second.

As the toner, there is used a polishing toner in which alumina, titania or the like is embedded as an abrasive on the surface of the toner particles and held so as to partially protrude from the surface. However, the present invention is not limited to this, and the abrasive may be electrostatically attached to the toner surface. In this way, the surface of the a-Si photosensitive drum polished so as to have a temperature of 500 ° or less does not easily adhere to the ion product and is easily removed, thereby suppressing image flow.

Hereinafter, embodiments of the present invention will be described. <Example 1> (Production of photoconductor and photoconductor polishing system) 40 mm in diameter
X 1% printing on A4 paper was performed using an a-Si photosensitive drum made with a size of 360 mm in length. To the toner, 3% of titanium oxide is added as an abrasive, and a roller made of embodied EPDM (outer diameter: 14 mm, sponge thickness: 2.0 mm, hardness: HS
35 degrees), and 100 g / cm of antiques on the drum surface
And a system for polishing the photoreceptor was provided. A screw for collecting toner was arranged at a position opposite to the photosensitive drum of the polishing roller. A polishing roller is provided with a clutch so that it can be switched between driven and stopped by an electric signal.During normal printing, driven and stopped for 0.1 second between printing and printing. Set.

(Printing test) KYOCERA FS-90 printing
00, and the image flow is H.00. H. Environment (30 ℃ 80
% RH) The image was confirmed after standing for 8 hours. The image flow is determined by rank, where 1 is a good side and 5 is a bad side.
The practical area was set to rank 1.5 or higher. The surface roughness of the photoreceptor drum after printing was measured using an atomic force microscope (AF).
According to M), 10-point average roughness (Rz) at a length of 100 μm
I asked.

The evaluation of the image deletion rank is as follows. 1: No fog was observed on the background portion of the print. 2: By using a loupe, fog is slightly observed in the background portion. 3: Fog is slightly observed in the background portion of the print by visual observation. 4: Fog is visually observed in the background. 5: Vertical streaks and the like appeared in the background portion, and remarkable fog was observed.

(Evaluation of Jitter) The effect on the image caused by the occurrence of jitter between the polishing roller and the photosensitive drum is that when a graphic pattern is output, a stripe pattern is formed at the intervals between the gear teeth of the drive system. It is.

For the evaluation of jitter, an image sample in which horizontal lines were written at one-line intervals along the printing direction was output, the image resolution was changed, and the resolution when jitter appeared was classified as follows.

No jitter is observed even at a resolution of 600 dots per 1 inch. 2. At a resolution of 600 dots per inch, slight jitter is observed. 3: Jitter is observed at a resolution of 300 dots per inch. 4: Jitter is seen at a resolution of 150 dots per inch. 5: Jitter is observed even at a resolution of 75 dots per inch. (Experimental Results) The results obtained by this experiment are shown in FIG. From these results, it was found that the surface roughness was improved by advancing printing, no image deletion occurred, and 6
Even when horizontal lines every other line were printed out at a resolution of 00 dots / inch, the jitter rank was 1 or 2, and a good image was obtained with almost no jitter.

<Comparative Example 1> The same experiment as in Example 1 was performed except that the elastic roller was forcibly stopped during non-printing irrespective of normal printing, and the occurrence of jitter was observed. As a result, jitters of ranks 4 and 5 were remarkably observed, and image defects occurred.

[0029]

As is apparent from the above description, according to the present invention, it is possible to suppress the image flow and to prevent the image defect due to the jitter at the time of printing.
Further, according to the present invention, since the heater temperature can be reduced, the heater capacity can be reduced, and the heater can be eliminated, energy can be saved and the heater warm time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a printer to which the present invention is applied.

FIG. 2 is an explanatory diagram of main parts of a photosensitive drum and a polishing roller.

FIG. 3 is a diagram showing the transition of the surface roughness of the photosensitive drum and the flow of the image with respect to the number of printed sheets (when the machine is started with A1 paper 1% printing and when a mode for forcibly polishing every 10,000 sheets is provided).

FIG. 4 is an explanatory view of a photoreceptor of the present invention.

[Explanation of symbols]

 1: Photoreceptor 2: Charger 3: Exposure source 4: Developing roller 5: Transfer roller 6: Polishing roller 7: Spring 8: Toner recovery screw 9: Cleaning blade 10: Static eliminator 11: Transfer paper 12: Clutch

Claims (2)

[Claims] An amorphous silicon photoreceptor; developing means for forming a toner image by adhering a polishing toner having an abrasive held on its surface to an electrostatic latent image of the photoreceptor; and supplying the polishing toner. Means, and a polishing means for pressing an elastic roller against the surface of the photoreceptor and polishing the surface of the photoreceptor by rubbing the elastic roller, the polishing toner supplied by the supply means and the polishing The surface roughness of the photoreceptor is reduced to 500 ° by interaction with the means.
In the image forming apparatus configured to print the toner image on a recording medium while polishing below, at the time of printing on the recording medium, the elastic roller pressed against the photoconductor performs a driven rotation with the rotation of the photoconductor, On the other hand, the image forming apparatus is characterized in that the rotation of the elastic roller is forcibly stopped during non-printing, and the surface is polished by sliding friction between the stopped elastic roller and the rotating photosensitive member. 2. The image forming apparatus according to claim 1, wherein the non-printing time is a time between recording media to be printed when the recording medium is continuously printed. .