JPH0324586A - Manufacture of roughened electrifying roller - Google Patents

Abstract

PURPOSE:To evenly roughen an electrifying roller by specifying the hardness of an elastic roller which brings a belt-like abrasive into press-contact with the electrifying roller. CONSTITUTION:When the surface of the prime electrifying roller is roughened, if the abrasive 12 is only made to abut on the electrifying roller 11, a part which is not in full contact with the abrasive 12 will occur from the eccentricity of the prime electrifying roller, some corrugation on the surface, etc. Therefore, the hardness of the elastic roller 14 for bringing the belt-like abrasive 12 into press-contact with the surface of the electrifying roller 11 is selected so that it is above 30 deg. and below 85 deg.. Thus, pressure is evenly applied on the prime electrifying roller and the surface of the electrifying roller 11 is evenly roughened.

Description

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

[Prior Art] Until now, as photoconductive materials used in electrophotographic photoreceptors,
Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known. These photoconductive materials have a number of advantages, such as being able to be charged to an appropriate potential in the dark, having little charge dissipation in the dark, or being able to rapidly dissipate charge when irradiated with light. On the other hand, it has various drawbacks. For example, in selenium-based photoreceptors, crystallization easily progresses due to factors such as temperature, humidity, dust, and pressure. Especially when the ambient temperature exceeds 40°C, crystallization becomes significant, resulting in decreased charging performance and white spots on images. There are drawbacks such as the occurrence of

Cadmium sulfide photoreceptors do not provide stable sensitivity in humid environments, and zinc oxide photoreceptors require the sensitizing effect of sensitizing dyes such as rose bengal. They have the disadvantage that they cannot provide stable images over a long period of time because the sensitive dyes undergo charging deterioration due to charging and photofading due to exposure light.

On the other hand, it has been discovered that certain organic compounds exhibit photoconductivity. For example, organic photoconductive polymers such as poly-N-vinyl rubber, polyvinyl anthracene, and low-molecular organic photoconductor phthalocyanine pigments such as carbazole, anthracene, birazolines, oxadiazoles, hydrazones, and polyarylalkanes. Organic pigments and dyes such as , azo pigments, cyanine dyes, polycyclic quinone pigments, berylene pigments, indigo dyes, thioindigo dyes, and methine squaric acid dyes are known. In particular, many proposals have been made for photoconductive organic pigments and dyes, which are easier to synthesize than inorganic materials, and the variety of compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. There is. For example, U.S. Pat. No. 4,123,270, U.S. Pat. No. 4,251,613, U.S. Pat.
No. 0672, No. 4268596, No. 427874
No. 7, No. 4293628, etc., an electrophotographic photoreceptor using a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer. etc. are known. In the charging process in an electrophotographic process using such an electrophotographic photoreceptor, charging is conventionally carried out using corona generated by applying a high voltage (DC 5 to 8 kV) 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 dirt on the wires affects image quality, resulting in white spots and black lines in the image. There were other problems.

On the other hand, in terms of power, the current flowing to the photoreceptor is 5 to 30
%, and most of it flowed to the shield plate, making it inefficient as a charging means.

In order to compensate for these drawbacks, many methods of direct charging have been researched and proposed (Japanese Patent Laid-Open No. 1782-1782).
67, 5 6 - 1 0 4. 3 5 1, 58-
40566, 58-139156, 58-150975
Public bulletins, etc.). The shapes of these direct charging members include rollers, brushes (including magnetic brushes), blades, and belts, which can be selected depending on the specifications and form of the electrophotographic apparatus.

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

In the direct charging method using a charging roller, when the distance between the photoreceptor drum and the charging roller becomes constant, discharge occurs and voltage is applied to the drum. Therefore, since the surface of the charging roller is flat, charging is often uneven due to the influence of unevenness or scratches on the surface of the photoreceptor drum.

Further, when 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] A first object of the present invention is to provide an electrophotographic apparatus using a charging roller, in which stains on the white background of an image due to non-uniform charging and toner adhesion on the charging roller occur. To provide a charging roller for an electrophotographic device that can stably supply high-quality copy images with almost no background smudges or the like.

The above objective can be achieved by providing unevenness on the surface of the charging roller whose maximum surface roughness, average surface roughness, and minimum surface roughness are all 0.3 μm or more and 5 μm or less according to the ten-point method. The present inventor has already proposed this.

However, there is still room for improvement in the control of the roughened state of the surface, which is presumed to be the cause of 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 increase the hardness of the elastic roller used to press the abrasive strip onto the charging roller by 30°. This is achieved by setting the angle to 85° or less.

[Means to solve the problem] The present invention will be explained in more detail below.

Materials for the charging roller used in the present invention include metals such as aluminum, iron, and copper, and conductive polymer materials such as polyacetylene, bolivirol, and polythiophene, which are treated with conductive rubber by dispersing carbon, metal, etc. Artificial fibers or insulating materials such as polycarbonate, polyvinyl acetate, and polyester whose surfaces are coated with metal or other conductive materials can be used. The volume resistance value of these conductive members is lO°~1012Ω
'Cffi is optimally in the range of 102 to lOl0Ω·cm. If an image is formed using a charging roller and a photoreceptor drum when the surface of the charging roller is not roughened, the charging roller and photoreceptor drum tend to stick together, and there is also a high probability that toner will adhere to the charging roller. Furthermore, since the surface of the charging roller is flat, defects (unevenness and scratches) on the drum are likely to be picked up during discharge, and uneven charging is likely 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 in the case of a sandblasting method or the like, the abrasive material is likely to be embedded in the charging roller, causing uneven charging, whereas in the case of a band-shaped abrasive material, this embedding is almost absent.

However, with conventional polishing methods, it is still difficult to uniformly roughen the surface of the charging roller, and as a result, the phenomenon of difficulty in uniform charging during charging has not been resolved. The inventors of the present invention have conducted intensive studies on roughening the surface of a charging roller, and as a result, have arrived at the present invention described below. That is, in a method of roughening the surface of a raw charging roller using a band-shaped abrasive material, the hardness of the elastic roller used to press the abrasive material against the charging roller is set to 30° or more and 85° or less. By forming fine irregularities on the surface of the raw charging roller using a surface roughening device, the maximum surface roughness, average surface roughness, and minimum surface roughness of the surface are all 0.3 to 5.0 μm. This is based on the knowledge that it is possible to achieve a uniform surface roughness within a certain range, and as a result, uneven charging on the surface of the charging roller, adhesion of toner, and adhesion to the photoreceptor drum can be substantially prevented. In other words, the present invention provides a method for roughening the surface of a raw charging roller using a band-shaped abrasive material, in which the hardness of an elastic roller for pressing the abrasive material onto the surface of the charging roller is 30' or more. The present invention relates to a surface roughening method characterized in that the roughening angle is selected to be 85° or less.

When roughening the surface of a raw charging roller using a band-shaped abrasive material, simply bringing the abrasive material into contact with the charging roller will be hindered by eccentricity of the raw charging roller, slight undulations on the surface, etc. Therefore, some parts may not come into sufficient contact with the abrasive material.

As a result, there is a drawback that unroughened portions or insufficiently roughened portions may remain.

However, the hardness of the elastic roller that is the presser roller is 3.
The main purpose of the method of the present invention is that if the angle is set to 0° or more and 85@ or less, a pressing force can be uniformly applied to the raw charging roller, and as a result, the charging roller surface can be uniformly roughened. However, if the hardness of the elastic roller is greater than 85°, deep scratches may occur on the surface of the charging roller. Therefore, it is necessary to set the hardness of the roller to 85 degrees. The hardness of the elastic roller used in the method of the present invention is a value measured by the following method.

In other words, it is called the JIS A measurement method among the measurement methods specified in JIS K6301.
The device used for this measurement has the trade name Techlock GS70.
6 [manufactured by Techlock (USA)].

The belt-shaped abrasive material used in the method of the present invention includes fine particles of aluminum oxide, silicon carbide, chromium oxide, diamond, etc., coated on a film of polyester, etc.
There is something fixed.

The roughened charging roller according to the method of the present invention can be used not only for copying machines but also for laser printers, LED printers, CRTs, etc.
It can be used in electrophotographic applications such as printers and electrophotographic plate making systems.

[Example] The method of the present invention will be explained in detail below using specific examples.

Example 1 A copying machine (NP-3525 manufactured by Canon) was modified as shown in FIG. 1 is a photoreceptor for the copying machine, 2 is a charging roller that performs direct charging, 3 is an image exposure device, 4 is a developing device, 5 is a paper feed roller and paper feed guide for transfer paper, 6 is a transfer charger, 7 8 is a separation charger, 8 is a conveyance unit that sends the transfer paper to a fixing device (not shown), 9 is a cleaner, 10 is a pre-exposure light source,
Reference numeral 100 denotes a power supply device that applies voltage to the charging member 2.

Charging roller No. 2 was manufactured by the following method.

Chlorobrene rubber [Product name Denkakuchi Robrene M-30]
5 parts by weight of conductive carbon [trade name: Conductex 900 manufactured by Columbian Chemical Co., Ltd.] was melt-kneaded with 100 parts by weight (manufactured by Denki Kagaku Kogyo ■) and molded with a stainless steel shaft passed through the center to form a plain charging roller.

The average surface roughness (R2) of this elementary charging roller surface is 0.2
μ oboro, and the minimum surface roughness and maximum surface roughness are each 07
They were 0 μm and 0.3 μm. This raw charging roller was pressed against a band-shaped abrasive material 12 (manufactured by Sumitomo 3M, trade name: Wrapping Film) with an abrasive particle size of 6.0 μm, and this abrasive material 12 and a charging roller 11 using the apparatus shown in FIG. When the surface was roughened using a rubber roller with a hardness of 60 @ as the elastic roller 14 used for
The average surface roughness (R2) of the charging roller 11 surface is 1.0μ
m, and the minimum surface roughness and maximum surface roughness are each 0.6
μm and 1.6 μm.

When this roughened charging roller 11 was installed in the above-mentioned modified copying machine and subjected to paper passing durability, no problems occurred up to 5,000 sheets.

The charging exposure conditions are a DC voltage of -750V on the charging roller.
By superimposing the AC peak-to-peak voltage of 1500 V, the image exposure amount is 3.
．． This was carried out at 0 lux·sec, a pre-exposure amount of 10, and 0 lux·sec.

Comparative Example 1 The hardness of the rubber roller 14 was set to 90 using the same device as in Example 1.
When the charging roller 11 was roughened by replacing it with
The average surface roughness (R2) of the surface is 3.3 μm. The minimum surface roughness and maximum surface roughness were 1.3 μm and 7.7 μm, respectively. This is because the hardness of the rubber roller l4 is too high, and the pressing force exerted by the abrasive material l2 on the charging roller 1l during surface roughening becomes too high, resulting in unnecessarily deep scratches on the surface of the charging roller 11. It is thought that this was done. When the charging roller l1 whose surface had been roughened in this way was installed in the same equipment as in Example 1 and subjected to paper passing durability under the same conditions, unevenness of the image due to charging unevenness and staining of the white background area were observed from the beginning of the durability. Endurance was canceled due to this problem.

Examples 2, 3, 4.5 and 6 Abrasive particle size 6.0μ used in equipment similar to Example 1
Rubber roller 14 with the hardness shown in Table 1 was used instead of band-shaped abrasive material 12 with abrasive grain size of 9.0 μm.
Processed with. The average surface roughness (R.), minimum surface roughness, and maximum surface roughness of the surface of the roughened charging roller 11 obtained and the roughened roller 11 were incorporated into the same electrophotographic apparatus as in Example 1, and 5000 Table 1 also shows the results of sheet feeding durability. Comparative Examples 2 and 3 Instead of the rubber roller 14 used in Example 2, rubber rollers having the hardness shown in Table 2 were subjected to surface roughening treatment.

Table 2> Above, Examples 1, 2, 3, 4.5 and 6 and Comparative Example 1
, 2, and 3, a rubber roller l4 used to press the abrasive material 12 against the charging roller 11
By roughening the surface using a material with a hardness of 30" or more and 851 or less, it is possible to obtain a charging roller with a uniformly rough surface. As a result, image unevenness, background stains, and
Also, it is possible to obtain a good image with almost no horizontal streaks caused by sticking with the photoreceptor roller.

The roughened charging roller according to the method of the present invention can be used not only for primary charging, but also for transfer charging, separation charging, etc., and as a 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 virtually no sticking or uneven charging between the charging roller and the photoreceptor drum, and background smearing due to adhesion of toner to the charging roller. , we were able to obtain stable repeated images.

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a copying machine incorporating a roughened charging roller obtained by the method of the present invention, and FIG. 2 is a schematic diagram of a roughening apparatus for carrying out the method of the present invention. 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 charger 8... Conveyance section 9 that feeds the transfer paper to the fixing device (not shown)...
・Cleaner O...Pre-exposure light source 1...Charging roller 2...Band-shaped abrasive material 3...Feeding roller 4...Press roller 5...Take-up roller O...Power supply device Fig. 1 Figure 2

Claims (1)

[Claims] (1) In a method of manufacturing a roughened charging roller by roughening the surface of the charging roller using a band-shaped abrasive material, the hardness of the elastic roller that presses the abrasive material against the charging roller is set to 30° or more. A method for producing a roughened charging roller, characterized in that the roughening surface is selected within a range of 85° or less.