JPH03120578A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To stably carry out cleaning with the surface of a carrier less abraded and less shaved by using a belt-like cleaning member having specific surface resistance for a part abutting on the surface of an image carrier. CONSTITUTION:A cleaning mechanism 2 is parallelly provided in the axial direction of the image carrier 1 rotating in an arrow direction. One part of the loop of the belt-like cleaning member 3 which is attached to the cleaning mechanism 2 and has surface resistance <=10<10>OMEGA abuts on the surface of the carrier 1. In a transfer part 10, the surface of the carrier 1 is rubber on the member 3 and the toner left on the surface of the carrier 1 is cleaned. The loop of the member 3 rotates in the opposite direction of the carrier 1, and the toner on the loop is recovered in a dust box 12. The loop of the member 3 has low surface resistance, so that it is not easily electrified and a toner attracting quantity is reduced. Thus, stable cleaning is carried out without turning over a blade.

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to an image forming apparatus using an electrostatic photographic process, such as an electrophotographic copying machine and a printer, and particularly to a cleaning apparatus therefor.

[Conventional technology]

In a well-known image forming apparatus that repeats the process of transferring a toner image electrostatically formed on an image carrier to a sheet-like transfer material mainly made of paper, the total amount of toner forming the toner image is not necessarily changed each time the toner image is transferred. Since the toner is not transferred to the transfer material, it is essential to sufficiently remove residual toner remaining on the surface of the image carrier after each transfer. Conventionally, as a cleaning means for this purpose, a cleaning blade made of an elastic material such as rubber is used, and one edge of the cleaning blade is brought into contact with the surface of the image carrier to scrape off the toner that reaches this area. It is well known that this technology has been widely put into practical use. The reason for this is thought to be that the structure is simple, the cost is low, and the toner removal function is excellent. This will be explained below based on the drawings. FIG. 2 is a schematic cross-sectional view of a typical example of such a leaning mechanism, and is parallel to the axial direction of a cylindrical image carrier 1 that extends perpendicular to the plane of the paper and rotates in the direction of the arrow. A cleaning mechanism 2 is arranged close to the cleaning mechanism 2, and one edge lla of the free end of the cleaning blade 11 attached to the cleaning mechanism 2 is in contact with the surface of the image carrier 1, and does not contribute to the transfer at a transfer site (not shown). The toner remaining on the surface of the image carrier 1 is removed by the blade 11 as it rotates.
When it reaches the abutment edge lla, it will be scraped off by this. The other end of the cleaning blade 11 is fixed to the support member 4. At this time, the free end edge of the cleaning blade 11 is often brought into contact with the image carrier 1 in the direction shown in the figure (in the counter direction with respect to the rotational direction of the image carrier 1), so that the toner is removed. However, on the other hand, it has the following disadvantages. That is, the contact edge ll of the cleaning blade 11
In order for a to perform a stable cleaning function, it must come into contact with the surface of the image bearing member 1 with uniform pressure over its entire length. Corona products due to the presence of high-voltage members within the apparatus, as well as paper dust and deposits from the corona particles, may adhere to the image carrier 1 and cause unevenness. Due to this cause, the friction between the cleaning blade 11 and the surface of the image carrier 1 becomes extremely large, and as a result, as shown in FIG. Functionality may be lost. Particularly in the case where the photosensitive layer on the surface of the image carrier 1 is formed of an organic semiconductor, the friction with the cleaning blade 11 is inherently large, so that the photosensitive layer is likely to turn over. In addition, in the case of non-magnetic developers, which have come into widespread use with the recent spread of multicolor copying, there is a tendency for poor cleaning and blade slippage to occur from both ends of the cleaning blade. In addition, paper powder that has not been completely cleaned and has adhered to the image carrier 1 is repeatedly used due to corona charging, and when it absorbs moisture, the electrical resistance significantly decreases, resulting in image blurring and image blurring. When cleaning using the cleaning blade 11,
Damage to the cleaning blade or vibration may cause toner to slip through, leading to poor cleaning (Especially when toner with a small average particle size is used, toner easily slips through during blade cleaning. Since the particle size of the toner is small, the specific surface area of the toner increases, and as a result, the toner tends to aggregate due to moisture absorption, etc. When the toner aggregates at the contact edge of the cleaning blade, the cleaning blade 11 and the photoconductor The absolute amount of toner, which also acts as a lubricant between Cleaning failures are likely to occur due to toner slipping through or the cleaning blade turning over.As a result, it becomes difficult to obtain stable and durable images.Also, when cleaning using a cleaning blade, the cleaning blade and image carrier Because the coefficient of friction between ,
It is difficult to obtain a stable image through a paper-running durability test. In order to eliminate such drawbacks, for example, Japanese Patent Application Laid-Open No. 61-2
As seen in Japanese Patent Application No. 12881, a structure in which both ends of the cleaning blade that contact the image carrier are cut off has been proposed, but with such a modification, toner running sideways to both ends of the cleaning blade is removed. There was no escape from defects that caused particles to scatter from the edges and contaminate the transfer material and the inside of the device. [Problems to be Solved by the Invention] The present invention has been made in order to cope with the above-mentioned situation, and is capable of always performing stable cleaning without causing the cleaning blade to turn over or toner to slip through in the cleaning mechanism. The purpose of this invention is to provide an electrophotographic apparatus that can perform the following functions. Another object of the present invention is to provide an electrophotographic apparatus configured so that paper dust and the like can be stably removed in a cleaning mechanism without causing image deletion or image blurring. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic apparatus in which wear and abrasion of the surface of an image carrier can be reduced in a cleaning mechanism. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for cleaning the surface of a belt-like cleaning member used in an electrophotographic cleaning mechanism that cleans an image carrier by bringing the belt-like cleaning member into contact with the image carrier. It is characterized by having a resistance of 1016Ω or less. By doing this, even toner having a small particle size can be efficiently cleaned from the surface of the image bearing member, and the turning of the leaning blade, which occurs in blade cleaning, does not occur. The configuration of the present invention will be explained below based on the drawings. The cleaning mechanism 2 that can be installed in the electrophotographic apparatus of the present invention has a belt-shaped cleaning member that comes into contact with the image carrier 1 for cleaning, and has a surface resistance of 10'. It is characterized by the following in Ω. FIG. 1 is a schematic cross-sectional view showing the structure of an electrophotographic apparatus used in the present invention. A cleaning mechanism 2 is disposed close to and parallel to the axial direction of a cylindrical image carrier 1 that extends perpendicularly to the plane of the paper and rotates in the direction of the arrow, and a surface resistor 1010 attached thereto.
A portion of the loop of the belt-like cleaning member 3 having a diameter of Ω or less is in contact with the surface of the image carrier 1 . The loop of the belt-shaped cleaning member 3 is supported by a plurality of support rollers 4. When the toner remaining on the surface of the image carrier 1 without contributing to the transfer at the transfer site 10 reaches the cleaning mechanism 2 as the image carrier 1 rotates, the toner that does not contribute to the transfer reaches the cleaning mechanism 2, where the surface resistance of the mechanism 2 is 1QlO or less. It is cleaned by rubbing against the shaped cleaning member 3. At this time, the loop of the belt-like cleaning member 3 moves in the direction opposite to the rotating direction of the image carrier 1 to clean the residual toner on the surface of the image carrier 1, and this toner falls into the dust box 12. With this mechanism, residual toner on the surface of the image carrier 1 is always cleaned by the clean surface of the belt-shaped cleaning member 3. According to the present invention, since cleaning is performed using a belt-like cleaning member, even if small particle size toner is used under strict cleaning conditions, toner slip-through and blade turning-up, which is seen in blade cleaning, will not occur. . Typically, a belt-shaped cleaning member becomes electrically charged when it is repeatedly used for cleaning. As a result, the cleaned toner is likely to be electrostatically attracted to the belt-shaped cleaning member. If this toner is adsorbed to the belt-shaped cleaning member, the residual toner on the surface of the image carrier 1 will not be completely cleaned, and cleaning defects are likely to occur. Therefore, in the cleaning mechanism 2 of the present invention, the belt-shaped cleaning member 3 has a surface resistance of 101 t'Ω or less, preferably 108Ω or less (measurement conditions: 25°C, 50% R
H) Since the belt-shaped cleaning member with low surface resistance is used, the belt-shaped cleaning member is less likely to be charged, and the amount of toner adsorbed to the belt-shaped cleaning member 3 after cleaning is reduced. can. By using a cleaning mechanism using this belt-like cleaning member, residual toner on the surface of the image carrier 1 can be almost completely cleaned. Examples of the belt-like cleaning member include woven fabrics made of fibers, nonwoven fabrics, and film-like or net-like sheets made of organic resins, inorganic resins, metals, ceramics, and the like. Examples of materials used to form the fibers include polyester, nylon, polyacrylonitrile, polyurethane, and polyvinyl acetate. To reduce the surface resistance of these materials, examples include treating them with an antistatic agent or incorporating them into a polymer. Methods such as incorporating Examples of the antistatic agent include quaternary ammonium salt type cationic surfactants, higher alcohol sulfate ester salt type anionic surfactants, and polyhydric alcohol type surfactants. Conductive fibers include metal fibers (gold, silver, stainless steel,
Examples include tungsten, alloys thereof, etc.), carbon-containing fibers, etc. As the material for the film or net-like sheet, organic resins such as polyolefin, polyvinyl chloride, and polyamide are easily used. To lower the surface resistance of film-like or net-like sheets,
Substances with low conductivity (for example, quaternary ammonium salts such as polyvinylbenzyltrimethylammonium chloride, anionic conductive resins such as polyacrylates and polyacrylic acids, carbon or metal fine powder, etc.) are added to the above organic resin. Apply or impregnate. Inorganic resins, ceramics, etc. may also be treated in the same way if their surface resistance is high. Photoreceptors to which the cleaning mechanism of the present invention can be effectively applied include silicon photoreceptors and organic photoreceptors. Other inorganic photoreceptors such as selenium, zinc oxide, cadmium sulfide, selenium-tellurium, and selenium-arsenic can also be used. Organic photoreceptors include organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, and low-molecular organic photoconductors such as carbazole, anthracene, birapurines, oxadiazoles, hydrazones, and polyarylalkanes. and phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments,
Organic pigments and dyes such as indigo dyes, thioindigo dyes, and squaric acid methine dyes are known. In particular, photoconductive organic pigments and dyes are easier to synthesize than inorganic materials, and the degree of freedom in selecting compounds that exhibit photoconductivity in an appropriate wavelength range has been expanded. Organic pigments and dyes have been proposed. For example, U.S. Patent Nos. 4,123.270 and 4.247.6.
No. 14, No. 4,251,613, No. 4.251.
No. 614, No. 4.256.821, No. 4.260
．． No. 672, No. 4.268.596, No. 4,27
As disclosed in No. 8°747 and No. 4.293.628, a disazo pigment exhibiting photoconductivity is used as a charge generating substance in a coated photosensitive layer which is functionally separated into a charge generating layer and a charge transporting layer. Electrophotographic photoreceptors are well known. In the electrophotographic apparatus of the present invention, cleaning is performed by bringing the belt-shaped cleaning member into contact with the image carrier, so that the blade dislocation that occurs in blade cleaning cannot occur. Since a belt-shaped cleaning member with a resistance of 10'.Ω or more is used, it is possible to efficiently clean toner, paper powder, and other stains on the image carrier.
Moreover, since toner is not easily adsorbed to the belt-shaped cleaning member, the cleaning performance in repeated durability tests is also good. Therefore, good image quality can be maintained even after repeated copying, with almost no background smudges, image blurring, or smearing caused by durability tests. Furthermore, unlike cleaning mechanisms that use cleaning blades, rollers, etc. that increase the contact pressure to the image carrier, a belt-shaped cleaning member is used for the contact part with the image carrier, making cleaning easier. Since the coefficient of friction between the member and the image carrier can be lowered, the surface of the image carrier can be less likely to be scratched even by repeated durability tests. From this, it can be said that the electrophotographic apparatus of the present invention is equipped with a leaning mechanism that is advantageous for organic photoreceptors, which are inferior to inorganic photoreceptors, especially in terms of wear resistance. Example 1 A cleaning mechanism was created using a carbon-containing polyester fabric having a surface resistance of 3XIO' [Ω] as the belt-shaped cleaning member 3 of the cleaning mechanism 2 shown in FIG. As the image carrier 1 with which the loop of the belt-shaped cleaning member 3 in the mechanism came into contact, an aluminum cylinder with a diameter of 80 mm was used, in which a photosensitive layer having the following structure was formed on the surface of the cylinder. , an ammonia aqueous solution of casein (casein 11.2 gr, 28% ammonia water 1 gr,
222 ml of water) was applied using a coating method and dried to a coating amount of 1. A subbing layer of Ogr/a'' was formed.Next, 1.0 part by weight of a charge generating substance represented by the following formula, 1 part by weight of butyral resin (trade name Kosuretsu 8M-2, manufactured by Sekisui Chemical Co., Ltd.) and isopropyl alcohol. 30 parts by weight were mixed and dispersed using a ball mill disperser for 4 hours, and this dispersion was applied onto the undercoat layer by dip coating and dried to form a charge generation layer.Thickness of the resulting film was 0.3 μm.Next, 1 part by weight of a charge transporting substance represented by the following formula (trade name: Kneepilon, manufactured by Mitsubishi Gas Chemical) and 6 parts by weight of dichloromethane were mixed, and the mixture was stirred with a stirrer. This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer.The thickness of the obtained film was 17 μm.This photoreceptor drum was coated with a photoreceptor. Examples 2 to 4 Example 1 was carried out using the same electrophotographic apparatus as Example 1 except that the belt-shaped cleaning member of the cleaning mechanism 2 of Example 1 and the average particle diameter of the toner used were changed. A durable image was produced in the same manner as in Table 1.The results are shown in Table 1.A photosensitive layer having the following structure was formed on the surface of an aluminum cylinder was used.The surface of the cylinder was coated with casein. An ammonia aqueous solution (casein 11.2gr, 28% ammonia water Igr, water 222a+1) was applied by a coating method and dried to form a subbing layer with a coating amount of 1.Ogr/sa''. Next, 1.0 parts by weight of a charge generating substance represented by the following formula, Example 5 A polyethylene sheet containing carbon powder (thickness: 50 μm) to create a cleaning mechanism. The image carrier 1 that the belt-shaped cleaning member 3 of the cleaning mechanism 2 comes into contact with has a diameter of 80 mm and is prepared by mixing 1 part by weight of butyral resin (trade name Kosuretsu 8M-2, manufactured by Sekisui Chemical) and 30 parts by weight of isobrobyl alcohol using a ball mill dispersion machine. After mixing and dispersing for 4 hours, this dispersion was applied onto the undercoat layer by dip coating and dried to form a charge generation layer. The thickness of the obtained film was 0.3 μm. Next, 1 part by weight of a charge transport substance represented by the following formula, 1 part by weight of polycarbonate resin (trade name: Niepiron, manufactured by Mitsubishi Chemical), and 6 parts by weight of dichloromethane were mixed and dissolved under stirring using a stirrer. This liquid was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The thickness of the obtained film was 18 μm. This photoreceptor drum is referred to as a photoreceptor 2. A copying machine [NP-35
25 (manufactured by Canon Inc.), no cleaning defects occurred, and an image equivalent to the initial image could be obtained even after the 80,000-sheet durability test. The remaining film thickness of the charge transport layer after a durability test of 50,000 sheets was 16.
It was 5 μm. The thickness of the scraping remained at 0.5 μm. When a durability test was conducted in the same manner as in Example 1 using the photoreceptor 2 prepared in this way, toner with an average particle size of 8 μm, and the cleaning mechanism described above, no cleaning defects occurred, and the final result was the same as the initial one. images were obtained. In addition, the remaining film thickness of the charge transport layer after the 50,000-sheet durability test was 17
, 7 μm, and the scraped thickness remained at 0.3 μm. Example 6 Example 5 was performed except that the belt-like cleaning member 3 of the cleaning mechanism 2 of Example 5 was a polyvinyl chloride sheet containing carbon powder, and the average particle size of the toner used was 10 μm.
A durable image production test was conducted in the same manner as in Example 1 using an electrophotographic apparatus similar to that of Example 1. The results are shown in Table 1. Examples 7 and 8 The belt-shaped cleaning member 3 of the cleaning mechanism 2 of Example 1 was changed to various types, and the photoreceptor used was α-S for negative charging.
A durable image production test was conducted in the same manner as in Example 1 using the same electrophotographic apparatus as in Example 1 except that the i-photoreceptor was used. The results are shown in Table 1. Comparative Example 1 A durable image was produced in the same manner as in Example 1 using the same electrophotographic apparatus as in Example 1, except that the belt-like cleaning member 3 of the cleaning mechanism 3 in Example 1 was changed to an untreated polyester fabric. I did this. The results are shown in Table 1. Comparative Example 2 Example 1 was carried out using the same electrophotographic apparatus as Example 5, except that the belt-shaped cleaning member 3 of the cleaning mechanism 3 of Example 5 was changed to a polyethylene sheet containing no conductivity imparting agent.
A durability test was conducted using the same method as above. The results are shown in Table 1. Comparative Example 3 A durable image was obtained in the same manner as in Example 1 using the blade cleaning mechanism used in a copier [NP-3525 (manufactured by Canon)] without using the belt-like cleaning member 3 used in Example 1. I did a test run. The results are shown in Table 1. [Effects of the Invention J The present invention is an electrophotographic apparatus characterized in that a cleaning mechanism uses a belt-shaped cleaning member that has a small number of parts that come into contact with an image carrier (both of which have a surface resistance of IQIOΩ or less). Therefore, unlike an electrophotographic apparatus using a cleaning blade, it is an object of the present invention to provide an electrophotographic apparatus that can perform stable cleaning at all times without causing the blade to turn over or toner to slip through. The electrophotographic apparatus is capable of stably removing paper dust and the like without causing image deletion or image blurring in the cleaning mechanism, and the image carrier is less likely to be scratched.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of the electrophotographic apparatus of the present invention, FIG. 2 is a schematic partial cross-sectional view showing the structure of a known blade cleaning mechanism, and FIG. 3 is a cleaning in the known blade cleaning mechanism. It is a schematic diagram which shows the contact state when a blade is turned over. 1, image carrier 2, cleaning mechanism 3, belt-like member 4, support member 5, pre-exposure 6, wide charger 7, image exposure 8, developing device 9, paper feed roller 10, transfer charger 11, cleaning blade 11a, normal abutment edge of the ri'J-nink blade 11b, ae)<t abutment edge of the blade 12, dust box

Claims (4)

[Claims] (1) In an electrophotographic cleaning mechanism that cleans a belt-shaped cleaning member by bringing it into contact with an image carrier, the belt-shaped cleaning member has a surface resistance of 10^1^0.
An electrophotographic device characterized by having a cleaning mechanism whose resistance is Ω or less. (2) The electrophotographic device according to claim 1, wherein the toner used in the electrophotographic device has an average particle diameter of 10 μm or less. (3) The electrophotographic apparatus according to claim 1, wherein the image carrier is made of a silicon photoreceptor. (4) The electrophotographic apparatus according to claim 1, wherein the image carrier is an organic photoreceptor.