JPH03234458A - Method and device for surface roughening of charged roller surface - Google Patents

Abstract

PURPOSE:To almost eliminate blots of the white ground part of an image due to unequal charging and stably obtain a copy image of high picture quality, by forming a pressing roller peripheral face of an elastic material, and performing a linear abutment or face-abutment while running a belt-like abrasive member at the angle of 0 deg. to 87 deg. to a generating line of a charged roller. CONSTITUTION:The surface of a charged roller 11 is subjected to roughening by abutting of a belt-like abrasive member 12 on the surface of the charged roller 11 by a pressing roller 14. In this case, the peripheral face of the pressing roller 14 is formed of an elastic material. Moreover, the belt-like abrasive member 12 is linearly or facially abuts on this charged roller 11 while traveling at the angle of 0 deg. to 87 deg. to the generating line direction 19 of the charged roller 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a charging roller used in an electrophotographic apparatus.

[Prior Art J] Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are already known as photoconductive materials used in electrophotographic photoreceptors. These photoconductive materials have numerous advantages,
For example, although it has advantages such as being able to be charged to an appropriate potential in the dark, having little dissipation of charge in the dark, and being able to quickly dissipate charge by irradiation with light, it also has various disadvantages. There is. For example, in a selenium-based photoreceptor,
Crystallization progresses easily due to factors such as temperature, humidity, dirt, and pressure. In particular, when the ambient temperature exceeds 40° C., crystallization becomes significant, resulting in disadvantages such as a decrease in chargeability and the appearance of white spots on images.

The disadvantage of cadmium sulfide photoreceptors is that they do not exhibit stable sensitivity in humid environments, and the disadvantage of zinc oxide photoreceptors is that they require the sensitizing effect of sensitizing dyes such as rose bengal. However, as a result of such sensitizing dyes causing charging deterioration due to charging and photofading due to exposure light, it is impossible to form a stable image over a long period of time.

On the other hand, certain organic compounds have been found to exhibit photoconductivity, such as: organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, small molecule organic photoconductors such as carbazole; , anthracene, pyrazolines, oxadiazoles, hydrazones, realyl alkanes, etc.; organic pigments and dyes such as phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, Squaric acid methine dye, etc.

In particular, many photoconductive organic pigments and dyes have been proposed because they are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. has been done.

For example, US Patent No. 4123270, US Patent No. 425161
No. 3, No. 4251614, No. 4256821,
Same No. 4260672, Same No. 4268596, Same No. 4
As disclosed in No. 278747 and No. 4293628, electrophotography uses a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer. Photoreceptors and the like are known.

In the charging process in an electrophotographic process using such an electrophotographic photoreceptor, charging has conventionally been carried out using corona generated by applying a high voltage (5 to 8 kV DC) to a metal wire. However, with this method, when corona occurs, corona products such as ozone and NOx alter the surface of the photoreceptor, causing image blurring and deterioration, and wire breakage affects image quality, resulting in white spots and black lines in the image. There were problems such as the occurrence of

On the other hand, in terms of electrical power, the current flowing to the photoreceptor is 5 to 30% of that amount.
Since most of the charge flows to the shield plate, this charging process has low efficiency as a charging means.

In order to compensate for these drawbacks, direct charging methods have been researched and many proposals have been made (Japanese Patent Laid-Open No. 57-1782
67.56-104351.58-40566.58-
139156.58-150975, etc.).

The shapes of these direct charging members include rollers, brushes (including magnetic brushes), blades, belts, etc.
It can be selected according to the specifications and form of the electrophotographic device.

However, unlike the corona charging method, in the roller charging method, the charging member and the photoreceptor drum are in direct contact, so there is a problem that the photoreceptor drum and the charging roller tend to stick together, and uneven charging tends to occur. There was a problem.

In the direct charging method using a charging roller, discharge occurs when the distance between the photoreceptor drum and the charging roller becomes constant, and a voltage is applied to the drum.

In this case, since the surface of the charging roller is flat,
Occasionally, unevenness or scratches on the surface of the photoreceptor drum caused uneven charging.

Furthermore, if the surface of the charging roller is flat, toner adheres to the charging roller during repeated image formation, which tends to cause scumming on the image.

[Problems to be Solved by the Invention] The first object of the present invention is to solve problems in an electrophotographic apparatus using a charging roller, such as staining of the white background area of the image due to non-uniform charging, and damage to the image due to toner adhesion on the charging roller. To provide a charging roller for an electrophotographic device that can stably supply high-quality copy images with almost no peeling.

The above purpose is to ensure that the surface of the charging roller has a maximum surface roughness, an average surface roughness, and a minimum surface roughness of 0.3 according to the ten-point method.
The present inventors have already proposed that this can be achieved by providing a rough surface with a roughness of 5.0 μm or more. However, it is still difficult to control the roughened state of the surface, which causes uneven charging.

Therefore, the second object of the present invention is to uniformly roughen the surface of the charging roller, and the purpose is to set the running direction of the abrasive strip at an intersection angle of 0 degrees or more with respect to the generatrix direction of the charging roller at an angle of 87 degrees. This can be achieved by using a polishing device set below.

[Means for Solving the Problems] The materials of the charging roller used in the present invention include metals such as aluminum, iron, and copper, conductive polymer materials such as polyacetylene, polypyrrole, and polythiophene, carbon,
Use conductive materials such as rubber, man-made fibers or synthetic fibers that have been treated to be conductive by dispersing metals, or insulating materials such as polycarbonate, polyvinyl acetate, and polyester whose surfaces are coated with metals or other conductive materials. be able to. The volume resistance value of these conductive members is 10° to 1012Ω・Cm, optimally 102 to 1
It is in the range of 0.010 Ωcm.

When an image is produced using a charging roller and a photoreceptor drum (hereinafter sometimes abbreviated as a "drum") when the surface of the charging roller is not roughened, the charging roller and photoreceptor drum may become loose. It is easy to stick, and there is also a high probability that toner will adhere to the charging roller. Moreover, the flat surface of the charging roller has the opposite effect, and tends to pick up defects (unevenness and scratches) on the photoreceptor drum during discharge, and as a result, uneven charging tends to occur.

For the above reasons, it is necessary to roughen the surface of the charging roller in advance.

Mechanical polishing is an excellent method for roughening the surface, and among these, a method using a band-shaped abrasive is more preferable. The reason for this is that when using a sandblasting method, etc., the abrasive material is easily embedded in the charging roller, which tends to cause uneven charging, whereas when using a strip-shaped abrasive material, this embedding hardly occurs. .

However, with conventional surface roughening methods, it is still difficult to uniformly roughen the surface of the charging roller, which causes a phenomenon in which uniform charging is not always performed during charging.

The inventors of the present invention have made the following findings as a result of intensive studies on roughening the surface of the charging roller.

That is, in a method of roughening the surface of a charging roller using a band-shaped abrasive material, the running direction of the band-shaped abrasive material is set at an intersection angle of 0 degrees or more and 87 degrees or less with respect to the generatrix direction of the charging roller. By roughening the surface, it is called maximum surface roughness, average surface roughness, and minimum surface roughness)
It has been found that uniform surface roughening can be achieved in which all of the roughness falls within the range of 0.3 to 5.0 μm, and as a result, charging unevenness can be substantially eliminated.

When roughening the surface of a charging roller using a band-shaped abrasive material, when the abrasive material is brought into contact perpendicularly to the generatrix direction of the charging roller, uniform pressure is applied to both edges of the abrasive material. Hard to apply pressure. As a result, the surface of the charging roller has become non-uniform.

Therefore, by changing the running direction of the belt-shaped abrasive material by a specific angle with respect to the generatrix direction of the charging roller and roughening the surface while it is in contact with the roller, any part of the surface of the charging roller can be roughened. As the inside of the abrasive material (inner side of both edges) is temporarily brought into contact with the polishing surface, the pressure applied to the polishing surface (or the polishing point) becomes almost uniform, resulting in uniform surface roughening. The main advantage of the present invention is that it can be used to

In implementing the surface roughening method of the present invention, an apparatus schematically shown in cross section in FIG. 2 can be used as an example. The elementary charging roller 11 is rotated clockwise. On the other hand, while the belt-shaped abrasive material 12 is being fed out from the delivery roller 13, the abrasive material is passed through the elastic presser roller 14 which is in pressure contact with the charging roller and taken up by the winding roller 13.
5 in the direction of arrow 16. At this time, the band-shaped abrasive material 12 rubs the surface of the raw charging roller 11 at the contact position of the presser roller 14. Furthermore, the method according to the invention can be schematically illustrated in FIG. 3 by way of example. That is, in the sliding portion of the charging roller 17, the traveling direction (arrow 18) of the belt-shaped abrasive material 20 is aligned with the direction of the generating line (arrow 19) of the charging roller.
The surface is roughened in the direction (arrow 20) perpendicular to the generatrix direction of the charging roller by setting the intersection angle θ to 0 degrees or more and 87 degrees or less.

Examples of belt-shaped abrasive materials used in the practice of the present invention include those in which fine particles of aluminum oxide, silicon carbide, chromium oxide, diamond, etc. are fixed to a film of polyester or the like by means of coating or the like.

The charging roller of the present invention can be used not only in copying machines but also in electrophotographic application fields such as laser printers, LED printers, CRT printers, and electrophotographic plate making systems.

Example 1 A copying machine [trade name: NP-3525 (manufactured by Canon)] was modified as shown in FIG. In the figure, 1 is the photoreceptor for the copying machine, 2 is the charging roller that performs direct charging, and 3
is the image drum light, 4 is the developer, 5 is the transfer paper feed roller and paper feed guy 1? , 6 is a transfer charger, 7 is a separation charger, 8 is a conveyance unit that sends the transfer paper to a fixing device (not shown), 9 is a beam 10 is a pre-exposure light source, 100 is a charging unit that applies voltage to the desk 2 It is a power supply device.

The charging roller No. 2 was manufactured by the following method. .

Chlorobrene rubber [Product name: Denka Chlorobrene M-3
0 (manufactured by Denki Kagaku Kogyo ■)] 100 parts by weight and 5 parts by volume of conductive carbon [trade name, Contact Us 900 (manufactured by Columbian Chemical Company)] are melted and kneaded, and the center of the resulting mass is coated with corrosion-resistant material. Shallow molding through a steel (stainless steel) shaft,
A plain charging roller 2 was used.

The average surface roughness (R7) of the surface of this elementary charging port 2 is 0.2LLm, and the minimum surface roughness and the maximum i\i7 phase 4
Momme was 0.0 gm and 0.3 μrn, respectively.

This raw charging roller was connected to the device U shown in Fig. 2 L'A, and a belt-shaped abrasive material with abrasive grain size of 9.0 μm [trade name Ni-wrapping film #2000 (manufactured by Sumitomo Three, J'mu Co., Ltd.)] was used. ] Run q:'r-, q was roughened using a polishing device set at an intersection angle of 87 degrees with respect to the direction of the charged Y]-ra-f-glue.

The average roughness (8,) of this charging roller surface is 1.0.
μm, minimum surface roughness and maximum surface roughness (J each 0
．． It was 82λIIl and L2μm.

When this roughened charging roller was installed in the above-mentioned modified copying machine and a paper passing durability test was conducted, no problems occurred up to 5,000 sheets. The results are shown in Table J.

The charging exposure conditions are a DC voltage of -750V on the charging roller.
and an AC peak-to-peak voltage of 3.500 V, an image exposure amount of 3.0 lux·sec, and a pre-exposure jll.

It was done in looks and seconds.

Examples 2 and 3 The surface of the raw charging roller was roughened using a polishing device in which the running direction of the belt-shaped abrasive material in Example J was set at an intersection angle of 45 degrees or 0 degrees with respect to the generatrix direction of the raw charging roller, respectively. .

The average surface roughness (R2) of the charging roller surface was 0.9 um (Example 2) and 1.9 um, respectively. I ILm (Example 3), and the minimum surface roughness and maximum surface roughness are 0.7 μm and 1.1 μm (Example 2) and 0.8, respectively.
μm and 1.3 μm (Example 3).

A paper passing durability test was conducted using each charging roller under the same equipment and conditions as in Example 1.
No problems occurred until the end.

The results are summarized in Table 1 as Examples 2 and 3 and are shown by -.

Comparative Example 1 A charging roller similar to that in Example 1 was prepared, and a paper passing durability test was conducted using the same equipment and conditions as in Example 1 without roughening the surface. Horizontal streaks due to sticking to the photoreceptor began to appear on the image. Show the results to the front panel with a comparative example.

Comparative Example 2 and Comparative Example 3 Example 1 The surface of the raw charging roller was roughened using a polishing device in which the running direction of the belt-shaped abrasive material was set at an intersection angle of 90 degrees or 88 degrees with respect to the generatrix direction of the raw charging roller, respectively. It became a face.

The average surface roughness (R2) of this charging roller surface is 1.5 μm (Comparative Example 2) and 1.4 μm (Comparative Example 3), respectively, and the minimum surface roughness and maximum surface roughness are 0.2 μm, respectively.
and 7.0 μm (Comparative Example 2) and 0.2 μm and 5.
It was 5 μm (Comparative Example 3).

Each charging roller was attached to the same device as in Example 1 and a paper passing durability test was conducted under the same conditions as in Example 1. In each case, image unevenness due to charging unevenness occurred from the beginning of the paper passing durability test. Contamination occurred in the white background area, and horizontal streaks due to adhesion between the charging roller and the photoreceptor began to appear on the image after about 50 sheets had been passed. Comparative example 2
The results are shown in Table 1.

Comparative Example 4 The surface of the raw charging roller was roughened using the polishing device in which the running direction of the belt-shaped abrasive material in Example 1 was set at a crossing angle of 90 degrees with respect to the generatrix direction of the raw charging roller.

However, in order to prevent both edges of the belt-shaped abrasive used from coming into contact with the charging roller, a mechanism is provided to lift both edges of the abrasive from the charging roller. The average surface roughness (R2) of this roughened charging roller surface was 1.0 μm, and the minimum surface roughness and maximum surface roughness were 0.8 μm and 1.2 μm, respectively.

This charging roller was installed in the same device as in Example 1, and
When a paper passing durability test was conducted under the same conditions as in Example 1, problems began to occur around 50 sheets passed. The results are collectively shown in Table 1 as Examples 2 and 3.

As shown in Examples 1 to 3 and Comparative Examples 1 to 4,
By roughening the surface of the charging roller using a device in which the running direction of the abrasive strip is set at an intersection angle of 0 degrees or more and 87 degrees or less with the generatrix direction of the raw charging roller, image unevenness, background smearing, and photosensitiveness can be reduced. It is possible to obtain a good image with almost no horizontal streaks caused by adhesion to the body.

Note that the roughened charging roller according to the method of the present invention is not limited to being used as a primary charging member, but can be used as any charging member such as a transfer charging member or a separation charging member.

[Effects of the Invention] When the charging roller whose surface has been roughened by the method of the present invention is used, there is almost no sticking between the charging roller and the photoreceptor drum, uneven charging, and background smearing due to toner adhesion to the charging roller, resulting in stable performance. Repeated images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a copying machine to which a roughened charging roller of the present invention is installed, FIG. 2 is a schematic cross-sectional diagram of a roughening device of the present invention, and FIG. 3 is a schematic cross-sectional view of a roughening device of the present invention. FIG. 2 is a schematic cross-sectional diagram of the surface roughening device of FIG. 1. Photosensitive drum, 2. Charging roller 3. Image exposure, 4. Developing device, 5. Transfer paper feed roller and paper feed guide, 6. Transfer charger, 7. Separation charging. 8...Fixing device (not shown), 9...Cleaner 12...Band-shaped abrasive material, 13...Feeding roller 14...Press roller 15...Take-up roller 16...Travel direction of the band-shaped abrasive material, 17・Charging roller during surface roughening ・Contact area between belt-shaped abrasive material and charging roller ・Generatrix direction of charging roller, 20 ・・Direction perpendicular to the generatrix direction of charging roller ・Band-shaped abrasive material ・Power supply device . 9 18 ・ 00

Claims (2)

[Claims] (1) A method for roughening the surface of a charging roller using a band-shaped abrasive material, characterized in that the angle between the running direction of the abrasive material and the generatrix direction of the charging roller is 0 degrees or more and 87 degrees or less. A method of roughening the surface. (2) A charging roller surface roughening device comprising at least a charging roller, a band-shaped abrasive material, and a presser roller that brings the abrasive material into contact with the surface of the charging roller, wherein the circumferential surface of the presser roller is formed of an elastic material. An apparatus characterized in that the abrasive material is brought into line contact or surface contact while traveling at an angle of 0 degrees or more and 87 degrees or less with respect to the generatrix of a charging roller.