JPH036577A - Method and device for roughening surface of electrostatic charging roller - Google Patents

Abstract

PURPOSE:To control the surface roughening state of the electrostatic charging roller by specifying the angle between the tangent direction of the abutting line between an abrasive material and the electrostatic charging roller and the generatrix direction of the electrostatic charging roller. CONSTITUTION:The angle between the direction of the abutting part between the filmy abrasive material 12 and electrostatic charging roller 11 and the generatrix direction of the electrostatic charging roller 11 is set to 3 - 87 deg.. The surface is therefore roughened uniformly so that the maximum value, mean value, and minimum value of roughness which are obtained by a 10-point mean roughness (RZ) measuring method defined by JIS (Japanese Industrial Standard) standard B0601 are all in a range of 0.3 - 5.3mum. Consequently, the staining of the white part of an image due to an irregularity in electrostatic charging and the ground staining of the image due to the sticking of toner on the electrostatic charging roller 11 are eliminated.

Description

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

[Conventional technology]

Until now, photoconductive materials used in electrophotographic photoreceptors have been
Inorganic photoconductive materials such as selenium, cadmium sulfide, and zinc oxide are known. These photoconductive materials have many 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, with 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 occurs significantly, resulting in decreased chargeability 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. Examples include organic photoconductive polymers such as I-N-vinylcarbazole and polyvinylanthracene, low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkane, as well as phthalocyanine pigments. Organic pigments and dyes such as azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindi dyes, and methine squaric acid dyes are known. In particular, many photoconductive organic pigments and dyes have been proposed because they are easier to synthesize than inorganic materials, and the parier technique has been expanded to allow selection of compounds that exhibit photoconductivity in an appropriate wavelength range. ing. For example, U.S. Patent Nos. 4,123,270, 4,251,613, and 425
No. 1614, No. 4256821, No. 426067
No. 2, No. 4268596, No. 4278747,
As disclosed in the same No. 4293628, an electrophotographic photoreceptor is known that uses a photoconductive disazo pigment as a charge generation substance in a photosensitive layer that is functionally separated into a charge generation layer and a charge transport layer. .

Charging in an electrophotographic process using such an electrophotographic photoreceptor is conventionally performed by applying a high voltage (DC 5 to 8 kV) to a metal wire and charging by corona generated. However, with this method, when corona occurs, corona products such as ozone and NOx alter the surface of the photoreceptor, causing image fading and deterioration, and dirt on the wires affects image quality, resulting in white spots and black spots in the image. There were problems such as streaks.

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 studied and proposed. (Unexamined Japanese Patent Publication No. 57-178
267, 56-104351, 58-40566゜5
8-139156.58-150975, etc.) The shapes of these direct charging members include rollers, brushes (including magnetic brushes), blades, and belts, which can be selected according to the specifications of the electrophotographic device. It is possible.

However, in the roller charging method, unlike corona charging, as a result of direct contact between the charging member and the drum, there are problems in that the drum and charging roller tend to swell and uneven charging tends to occur.

In the direct charging method using a charging roller, when the distance between the drum and the charging roller becomes constant, discharge occurs and a 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 drum surface.

Furthermore, if the surface of the charging roller is flat, toner tends to adhere to the charging roller during repeated image formation, causing background stains on the image.

[Problem that the invention is trying to solve]

The first object of the present invention is to provide an electrophotographic device using a charging roller, which is stable, with almost no stains on the white background of the image due to non-uniform charging or background stains due to toner adhering to the charging roller. An object of the present invention is to provide a charging roller for an electrophotographic device that can supply high-quality copy images.

The above purpose is to ensure that the surface of the charging roller has a ten-point maximum surface roughness, a ten-point average surface roughness, and a ten-point minimum surface roughness of 0.3.
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 uniformly roughen the surface of the charging roller, and to This can be achieved by setting the angle between the roller and the generatrix direction to be 3 degrees or more and 87 degrees or less.

[Means for solving problems]

The present invention will be explained in more detail below.

The material of the charging roller used in this initiative is 7/l.
/ Rubber, artificial fibers, polycarbonate, polyvinyl acetate, polyester, etc. that have been treated to be conductive by dispersing carbine, metal, etc. in conductive polymer materials such as minilum, iron, copper, etc., polyacetylene, polypyrrole, / IJ thiophene, etc. An insulating material whose surface is coated with metal or other conductive material can be used.

The volume resistance value of these conductive members is 100 to 1o1
The resistance is 2Ω, and the optimum range is 102 to 1010Ω.

When improving image quality using a charging roller and a photoreceptor drum (hereinafter sometimes simply referred to as a "drum") when the surface of the charging roller is not roughened, the difference between the charging roller and the drum is 9. Also, there is a high probability that toner will adhere to the 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, resulting in uneven charging.

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

Machine polishing is an excellent method for roughening the surface, and a method using a band-shaped abrasive is more preferred. The reason for this is that when using a sandblasting method, etc., the abrasive material is easily embedded in the charging roller, causing uneven charging, whereas when using a strip-shaped abrasive material, this embedding hardly occurs. be.

However, with conventional polishing methods, it is still difficult to uniformly roughen the surface of the charging roller, which has caused 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 angle between the tangential direction of the contact portion of the band-shaped abrasive material and the charging roller and the generatrix direction of the charging roller is 3 degrees. By roughening the surface of the charging roller by setting the temperature to 87 degrees or less, a uniform roughness can be obtained in which the maximum surface roughness, average surface roughness, and minimum surface roughness are all within the range of 0.3 to 5.0 μm. Surface formation can be achieved, and as a result, charging unevenness can be substantially eliminated. Here, the maximum surface roughness, average surface roughness, and minimum surface roughness refer to the maximum value, average value, and minimum value obtained by the ten-point average roughness (RZ) measurement method defined in JIS standard BO601.

That is, the present invention provides a method for roughening the surface of a charging roller using a band-shaped abrasive material, in which the intersection angle between the tangential direction of the abutting portion of the band-shaped abrasive material and the charging roller and the generatrix direction of the charging roller is 3 degrees. The feature is that the surfaces are roughened by bringing the two into contact with each other so that the angle is 87 degrees or less.

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 becomes unevenly roughened. Therefore, by changing the direction of the contact area between the abrasive strip and the charging roller by a specific angle and roughening the surface while they are in contact, any part of the surface of the charging roller can be temporarily polished. Even if the edges of the material are unevenly polished, the interior of the material (
As a result, the pressure applied to the polished surface (or polishing point) becomes almost uniform, and the surface roughening can be made uniform. He has a great eye for invention.

For carrying out the surface roughening method of the present invention, an apparatus schematically shown in cross section in FIG. 2 can be used as an example. Rotate the charging roller 11 clockwise or counterclockwise. On the other hand, the cloth-like abrasive material 12 is fed out by a roller 13
The sheet is fed out from the sheet and moved in the direction of arrow 16 to a take-up roller 15 via a rubber pressing roller 14 that is in pressure contact with a charging roller. At this time, the band-shaped abrasive material 12 rubs the surface of the charging roller 110 at the suppressed position of the presser roller 14. Furthermore, the invention can be illustrated schematically by way of example in FIG. That is, in the sliding portion of the charging roller 17, the angle θ between the tangential direction (arrow 18) of the abutting portion of the belt-shaped abrasive material 21 and the charging roller and the matrix direction (arrow 19) of the belt WL roller is set to 3 degrees. The surface is roughened in a direction perpendicular to the generatrix direction of the charging roller (arrow 20) by setting the surface roughness to a degree not less than 100 degrees.

Examples of belt-shaped abrasive materials used in the practice of the present invention include those made by coating and fixing fine particles of aluminum oxide, silicon carbide, amorphous/loam, diamond, etc. on a film of polyester or the like.

Obi of the present invention 'if! The roller can be used not only in copying machines but also in general electrophotographic fields such as radar printers, LED printers, CRT printers, and electrophotographic plate making systems.

The present invention will be explained in detail below using specific examples.

(Example 1) A Canon copier NP-3525 was modified as shown in FIG. 1 is a photoreceptor for NP-3525.

2 is a band '4c1-ler where direct charging is performed; 3 is image exposure; 4 is a developing device; 5 is a transfer paper feed roller and paper feed guide; 6 is a transfer charger; 7 is a separation charger; 8 is a separation charger. 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, and 100 is a power supply device that applies voltage to the charging member 2.

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

/ o a 7° Len Rubber [Denka Chloropre 7M-3
0 Denki Kagaku Kogyo Co., Ltd.] 100 parts by weight and 5 parts by weight of conductive carbon (Contactex 900 Near CI Ambient Chemical Powers Co., Ltd. a) were melt-kneaded and molded through a stainless steel shaft through the center to form a charging roller. .

The average surface roughness (Rz) of the different surface of this charging roller is 0.2
61 in μm, and the minimum and maximum surface roughness are o, respectively.

μm, 0.3 μm.

This charging roller was set using the device shown in FIG. 2 so that the tangential direction of the contact portion of the belt-shaped abrasive material and the charging roller was at an angle of 3 degrees with respect to the generatrix direction of the charging roller. The optical surface was roughened using a polishing device. The surface average surface roughness (Rx) of this charging roller is 1.0 μm
The minimum and maximum surface roughness are 0.8 μm and 1.
It was 2 μm. When this charging roller was installed in the above-mentioned modified copying machine and subjected to paper passing durability, no problems occurred up to 5,000 sheets. This is Example 1 and the results are shown in Table 1.

In addition, the charging exposure conditions are a II current voltage of -75 to the charging roller.
0 V and an AC peak-to-peak voltage of 1500 V were superimposed, the image exposure amount was 3.0/I/lux/sec, and the pre-exposure i was 10.0 lux/sec.

(Example 2.3) In Example 1, the tangential direction of the abrasive strip and the contact portion of the Teflon roller was set at an angle of 45 degrees or 90 degrees with respect to the generatrix direction of the charging roller. The surface of the charging roller was roughened using a polishing device with different settings.

The average surface roughness (Rz) of this charging roller was 0.9 μm (Example 2).

1 and 1 μm (Example 3), and the minimum surface roughness and maximum surface roughness were 0.7 μrn and 1.1 μm, respectively (Example 2).
) and 0.8 μm, 1.3 μm (*Example 3)
It happened.

When a similar experiment was conducted using a charging roller similar to that used in Example 1, no problems occurred up to 5,000 sheets. The results are shown in Table IK as Examples 2 and 3, respectively.

(Comparative Example 1) A charging roller similar to that in Example 1 was made, and paper passing durability was carried out under the same equipment and conditions as in Example 1 until the surface did not become rough. Horizontal μ due to smearing with the photoreceptor began to appear on the image. This was taken as Comparative Example 1 and the results are shown in Table IK.

(Comparative Examples 2 and 3) In Example 1, the tangential direction of the contact portion between the abrasive material and the charging roller is 0 with respect to the generatrix direction of the charging roller.
The surface of the charging roller was roughened using a polishing device set to have an angle of 1° or 2°. The surface average surface roughness (Rz) of this charging roller is 1.5μ, respectively.
m (Comparative Example 2) and 1.4 μm (Comparative Example 3), and the minimum and maximum surface roughnesses were 0.2 μm and 7.0 μm (
Comparative Example 2) and 0.2 μm, 5.5 μm (Comparative Example 3)
I failed. When we conducted experiments using the same equipment as in Example 1, we found that in all cases, image unevenness due to charging unevenness and stains on the white background occurred from the beginning of paper passing durability, and after about 50 sheets had passed. , horizontal streaks due to smearing between the charging roller and the photoreceptor began to appear on the image. These are shown in Table 1.

(Comparative Example 4) In Example 1, the polishing device was set so that the tangential direction of the abrasive material and the contact portion of the charging roller was at an angle of 0 degrees with respect to the generatrix direction of the charging roller. The surface of the charging roller was roughened. However, both edges of the round band-shaped abrasive material used were placed so as not to come into contact with the charging roller. Therefore, a device is provided to lift both edges of the abrasive material from the contact portion of the charging roller. The average surface roughness (Rz) of this polished charging roller was 1.0 μm, and the minimum surface roughness and major surface roughness were 0.8 μm and 1.2 μm, respectively. Then, when an experiment was conducted in the same manner as in Example 1 using this charging roller, no problem occurred up to 5,000 sheets. This was treated as Comparative Example 4 and the results are shown in Table 1.

As shown in Examples 1 to 3 and Comparative Examples 1 to 4,
Surface treatment of the charging roller is carried out using a device having a belt-shaped abrasive material in which the angle between the tangential direction of the contact portion of the abrasive material and the charging roller and the generatrix direction of the charging roller is 3 degrees or more and no more than 3 degrees. As a result, it is possible to obtain a good-looking image free from unevenness in one image, background smudges, and horizontal streaks caused by contact with the photoreceptor.

In addition, the charging roller according to this proposal is not only capable of primary charging, but also
Any of them can be used as a transfer charging member, a separation charging ring, and a charging member.

〔Effect of the invention〕

When the charging roller of the present invention is used, there is almost no smudging or charging unevenness between the band 11Lc2-r and the photoreceptor drum, and there is almost no background smudge due to toner layering on the band 40-r, and stable repeated images can be produced. can get fco

[Brief explanation of drawings]

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 unit that sends the transfer paper to the fixing device (not shown); 9.
...Cleaner 10...Pre-exposure light source, 11...Charging roller 12...Film-like abrasive material, 13...
Feeding roller 14... Pressing roller 15.
... Winding roller 17 ... Charging roller 18
...Band-shaped abrasive material and band-to-roller contact part, 19...
- Generatrix direction of the charging roller, 20... Direction perpendicular to the generatrix direction of the charging roller, 21... Band-shaped abrasive material, 100
...Power supply device.

Claims (2)

[Claims] (1) In a method of roughening the surface of a charging roller using a band-shaped abrasive material, the angle between the tangential direction of the line of contact between the abrasive material and the charging roller and the generatrix direction of the charging roller is 3 degrees or more. A surface roughening method characterized by roughening the surface to 78 degrees or less. (2) A charging roller surface roughening device comprising at least a charging roller, a band-shaped abrasive material, and an extrusion roller that brings the abrasive material into contact with the surface of the charging roller, in which the peripheral surface of the extrusion roller is formed of an elastic material. An apparatus characterized in that the abrasive material is brought into line or surface contact at an angle of 3 degrees or more and 87 degrees or less with respect to the generatrix of a charging roller.