JP2002268494A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cleaning performance of a cleaning device in an image forming device where a photosensitive body is electrified and exposed to form an electrostatic latent image and the electrostatic latent image is made visible as a toner image and the surface of the photosensitive body is cleaned by the cleaning device after transfer of the toner to a transfer material. SOLUTION: A cleaning device 6 is provided with first and second cleaning blades 1 and 11, and a voltage is applied to the first cleaning blade 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic method for a facsimile machine, a laser beam printer, a copying machine, etc., which can maintain a good image quality for a long period of time by keeping the surface of a photosensitive member clean. And an image forming apparatus using the same. More specifically, substances (contaminants) remaining on or adhering to the photoreceptor after transfer of the toner image, such as toner, paper dust, and corona products, which deteriorate the image quality in the next copy cycle are contaminated. The present invention relates to an image forming apparatus using a cleaning device capable of effectively removing and maintaining the surface of a photoreceptor so as to obtain good image quality.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic method, such as a facsimile, a laser beam printer, and a copying machine, devices such as charging, image exposure, development, transfer, separation, cleaning, and charge removal are arranged around a photoreceptor. The image forming is performed by these devices sequentially acting on the photoreceptor. A DC voltage or a DC voltage obtained by superimposing an alternating voltage on a charging device such as a corona charging device or a contact charging device is applied to the photoconductor, and the photoconductor is brought to a surface potential (for example, 400 to 1000 V in absolute value) necessary for image formation. Be charged. At the time of this charging, corona products such as ozone and nitrogen oxides are generated as discharge products other than the charges. These corona products adhere to the surface of the photoreceptor shortly after the discharge, and cause a reduction in image quality such as a reduction in resolution or image deletion.

[0003] An electrostatic latent image corresponding to the image is formed on the photoreceptor by image exposure with the charged LD light or the like, and is visualized (toner image) by the action of a developer. The components of the toner are pigments, resins, polarity control agents, lubricating substances such as silica, and the like. A part of this component is fixed to the photoreceptor by the pressure of the cleaning blade and the action of the corona product, and the toner filming layer is formed. To form The occurrence of filming causes phenomena such as image unevenness, background contamination, reduced resolution, and image deletion.

[0004] The toner image is transferred by a transfer device to a transfer material that has entered. When copy paper is used as the transfer material, the copy paper is made of cellulose, talc, silica,
It is composed of a binder and the like, and this constituent substance is released on the copy paper surface and adheres in a small number in the form of paper powder. This paper dust adheres to the photoreceptor, causing filming,
Similar to the above-described phenomenon, it causes a reduction in resolution and an image deletion phenomenon. The factors (contaminants) that cause such a decrease in resolution, image deletion, and the like have no actual harm and can be removed relatively easily if they are immediately after the attachment. Normally, contaminants adhering to the photoreceptor are removed to some extent by shaving the photosensitive layer and the contaminants by a developing device and a cleaning device.
An almost practically acceptable level of image quality is provided. However, when the photoreceptor has high wear resistance, when the copying speed is high, when copying a large amount, etc., as the edge of the cleaning blade wears, the cleaning device and the developing device keep the photoreceptor surface clean. It becomes insufficient to maintain it, and sometimes the image quality deteriorates as described above.

In order to maintain the image quality in a good state, it is necessary to suppress the adhesion of contaminants to such an extent that the image quality of the toner image on the photoreceptor is not deteriorated or to prevent the influence of moisture in the atmosphere from being accepted. Safeguards need to be taken. Examples of methods for improving image deletion (white spots) caused by corona products, photoreceptor surface oxidation, toner filming, paper dust adhesion, and the like include the following disclosure examples.

1) A method in which a photosensitive member is heated to 40 to 60 ° C. to prevent a decrease in surface resistance and to suppress a decrease in resolution (for example, JP-A-63-40181 and JP-A-62-2961).
No. 80, Japanese Unexamined Patent Application Publication No. Sho 51-65541, Japanese Unexamined Patent Application Publication No. Sho 60-95
No. 467, etc.) 2) A method of wiping the surface of the photoreceptor to remove corona products adhered to the surface to prevent the resolution from deteriorating (for example, JP-A-58-157549, JP-A-60-173570).
3) A method of cleaning the photosensitive layer with activated carbon fiber to remove corona products (for example, US Pat. No. 5,264,903;
4) A method of cleaning with a nonwoven fabric of ultrafine fibers to remove corona products (for example, JP-A-5-150693, JP-A-5-134585, JP-A-8-248820, etc.) 5) Ozone In order to avoid white spots and white streaks on the image due to NOx, prevent deformation of the cleaning blade, and maintain a stable image for a long period of time, remove the toner, carrier, and the like in order from the transfer device side. A residual developer removing member and a forced scraping member for removing fixed substances such as ozone and NOx are arranged (Japanese Patent Application Laid-Open No. 9-230767). 6) A first blade cleaning unit and a first blade in order from the transfer device side in order to avoid an abnormal image (a background stain, a white streak, a black streak due to charging failure, etc.) occurring in the image forming apparatus using the charging roller. Means that a second blade cleaning means having a low electric resistance and capable of applying a voltage is arranged (JP-A-9-296250).

[0007]

As described above, the contamination of the surface of the photoreceptor with contaminants such as corona products, toner components, and paper powder lowers the surface resistance of the photoreceptor, resulting in lower resolution. This causes image deletion and the like. Also,
The blade edge is damaged by contaminants attached to the photoreceptor, poor cleaning, black stripes, reduced durability of the cleaning blade, deterioration of electrophotographic characteristics in the photoreceptor,
It causes a decrease in mechanical durability such as scratching and uneven wear. Further, these foreign substances adhering to the photoreceptor are re-adhered to the charging roller, locally causing poor charging, causing black streaks and image unevenness. Therefore, in an image forming apparatus using an electrophotographic method, a cleaning unit for always keeping a photosensitive member in a clean state is particularly important. Regarding cleaning means or means for improving image deletion, etc., many solutions have been proposed as seen in the disclosed examples.
At present, there is a difference in effects depending on system conditions, and a fundamental solution has not been reached.

The present invention is based on the view that there is no other way to maintain good image quality over a long period of time except to keep the photoreceptor surface clean at all times. The contaminants adhering to the photoreceptor, which is the cause of the occurrence, are surely removed in each copy cycle, and the surface condition of the photoreceptor is always kept clean so that the image quality can be maintained for a long time in a good condition. In addition to maintaining the cleaning blade, the deterioration and damage of the cleaning blade are reduced.
An object of the present invention is to provide an image forming apparatus capable of improving the overall reliability of an image quality, a photoreceptor, a blade, a charging member, and the like by suppressing contamination of a charging member, rubbing noise, and the like.

[0009]

According to the present invention, in order to achieve the above object, a photosensitive member is charged by using a charging device, an electrostatic latent image is formed by image exposure, and an electrostatic latent image is formed by a developer. Developing the toner image on the photoconductor by a transfer device, transferring the toner image on the photoconductor to a transfer material, and removing the residual toner on the photoconductor after the toner image is transferred by the cleaning device. The cleaning device has at least a first cleaning blade and a second cleaning blade that are in contact with the photoreceptor, and the first cleaning blade is provided on a photoreceptor surface portion upstream of the second cleaning blade in the photoreceptor surface movement direction. First and second cleaning blades are provided so as to be in contact with each other, and the first cleaning blade is formed of an elastic member to which a voltage can be applied. We propose an image forming apparatus, characterized in that (claim 1).

At this time, the first cleaning blade is
It is advantageous if it is grounded or a DC voltage, an AC voltage or a DC voltage with an alternating current is applied (claim 2).

In the above image forming apparatus, the contact pressure of the first cleaning blade against the photosensitive member is set lower than the contact pressure of the second cleaning blade against the photosensitive member. It is advantageous (claim 3).

Further, in the image forming apparatus according to any one of claims 1 to 3, wherein the cleaning device is located downstream of a contact position of the first cleaning blade with respect to the photoconductor with respect to a moving direction of the photoconductor surface. It is advantageous to have a cleaning brush on the side of the photoconductor surface upstream of the contact position of the second cleaning blade with respect to the photoconductor.

In the image forming apparatus according to any one of claims 1 to 4, it is advantageous to use a photosensitive member having a coating layer having a thickness of 2 to 8 μm in which inorganic fine particles are dispersed on the photosensitive layer. (Claim 5).

Further, in the image forming apparatus according to any one of claims 1 to 5, lubricity is given by applying a lubricant to the surface of the photoreceptor by an external addition method, and the friction coefficient of the surface of the photoreceptor is set to 0.1. It is advantageous to set the range to 5 or less and 0.1 or more (claim 6).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The image forming apparatus of this embodiment is provided with two cleaning blades or two cleaning blades in order to surely remove various contaminants adhering to a photoreceptor which affects image quality. A cleaning device having a cleaning brush disposed between the blades is disposed between the transfer device and the charging device. The cleaning blade on the transfer device side is a first cleaning blade, and the cleaning blade on the charging device side is a second cleaning blade. The first cleaning blade is made of an elastic member to which a voltage can be applied, for example, a rubber material. To configure the first cleaning blade Voltage applied may be which a conductive or semi-conductive and, for example, the volume resistivity of 10 ⁰ to 10 ¹¹ Omega · cm, preferably 10 ⁰ to 1
0 ¹⁰ Omega · cm, particularly preferably 10 ⁰ to 10 ⁸ Omega · cm
Set to. Such a cleaning blade has a hardness of 50.
It is preferable that the blade is made of an elastic member (preferably a rubber type) having a heat resistance, ozone resistance, abrasion resistance, and non-polluting properties of about 80 to 80 degrees and a thickness of about 1.5 to 4 mm. The conductivity of the cleaning blade can be achieved by adding materials such as carbon powder, carbon and alkali metal salts. The best rubber material is urethane rubber,
BSR, CR, silicone rubber and the like can also be used.

The first cleaning blade is made conductive or semiconductive (medium resistor) by applying a voltage to the cleaning blade. This is for facilitating removal of toner and the like. When a voltage is applied, it is possible to select any one of a DC voltage, an AC voltage, and a DC voltage in which an AC voltage is superimposed according to use conditions, and the cleaning blade can be grounded (0 V) (see FIG. 1, see FIG. 2).

The reason why the cleaning blade is grounded or cleaned while applying a voltage thereto is to electrostatically remove a residue such as toner and paper powder on the photosensitive member. If the toner or paper dust remains on the photoconductor due to poor cleaning, the toner or paper powder gradually adheres to the photoconductor surface due to heat, pressure, and the like generated during repeated use, and tends to cause filming. That is, since the toner and paper powder after passing through the transfer device are electrostatically and physically attached to the photoreceptor, they can be used for a long time with a single cleaning blade as in the conventional blade cleaning system. In such a case, or in the case of a photoreceptor with significantly improved abrasion resistance or a model with a high copying speed, the blade edge is worn, etc. Affects quality. This cleaning failure can improve the cleaning efficiency by using two blades, but care must be taken in the mounting position of the two cleaning blades. If you do too much,
The toner blocked by the second cleaning blade is not removed, and there is a risk of adversely affecting the photosensitive member, such as filming, black bands, and poor cleaning. Therefore, it is preferable to set the positions where the first and second cleaning blades come into contact with the photoconductor so that such a problem does not occur.

By applying a voltage to the cleaning blade, toner, paper dust and the like are electrostatically lifted or sucked from the photoreceptor, and residues such as toner and paper dust on the photoreceptor are removed. However, the transfer residual toner and paper powder do not have uniform polarity and electric charge, and may be positive, negative, or almost 0V. Therefore, the voltage condition such as the polarity of the voltage applied to the first cleaning blade or its value (including 0 V) needs to be changed according to the system conditions. A voltage having a polarity capable of electrostatically attracting toner or the like on the photoconductor is applied to the first cleaning blade, or the first cleaning blade is grounded.

When the edge of the cleaning blade is worn, the cleaning performance of the photoconductor is reduced and the photoconductor is easily contaminated. Therefore, as much as possible, the first cleaning blade removes contaminants and removes the remaining contaminants. It is preferable that the photoconductor is always kept in a clean state by removing the substance and the corona product that is hard to be removed by the second cleaning blade or the cleaning brush.

It is desirable that the contact pressure of the first cleaning blade against the photosensitive member be set lower than the contact pressure of the second cleaning blade against the photosensitive member. For example,
The contact pressure of the second cleaning blade is 60 to 80 mN
/ Cm, the contact pressure of the first cleaning blade is set to 60 mN / cm or less. This is because if the amount of toner and paper dust is large, the photoconductor is easily damaged. By grounding the first cleaning blade or applying a voltage thereto, the first cleaning blade contacts the photoconductor. The pressure can be set low. The toner or the like that has escaped from the first cleaning blade can be supplemented by a second cleaning blade or a cleaning brush. However, even if a voltage is applied to the first cleaning blade, if the contact pressure of the first cleaning blade is reduced more than necessary, cleaning failure occurs. Therefore, it is preferable that the pressure is at least higher than 40 mN / cm. By removing most of the residual toner by the first cleaning blade, the contact pressure of the second cleaning blade against the photoconductor can be reduced, and thus the durability of the photoconductor as well as the cleaning blade can be reduced. Can be prevented from lowering. The voltage applied to the first cleaning blade is, for example, a DC voltage 20 in absolute value.
The AC voltage may be set to about 0 to 800 V, the AC voltage may be set to 200 to 1500 V, and the frequency may be set to a sine wave of 100 to 2000 Hz.

As for the method of contacting the cleaning blade with the photoconductor, the first cleaning blade may be either a reading system or a counter system. However, in consideration of the load on the photoconductor and space saving, the first cleaning blade is used as a leading system. It is preferable that the second cleaning blade be a counter system in view of cleaning performance.

The cleaning brush is used for excavating and removing extremely fine corona products, which are difficult to remove with a cleaning blade, and reactants of the corona products with oxides and resins on the photoreceptor, thereby further cleaning the photoreceptor. It is an effective means for making However, the cleaning brush is sufficiently effective even in an apparatus having a copy speed of about 10 to 20 cpm, but the accumulation speed of contaminants is high, and the consumption of the cleaning member is high.
m or more, the effectiveness is particularly high. cpm is
Indicates the number of copies per minute.

By using the cleaning device as described above, it is possible to almost eliminate contaminants which reduce the image quality on the photoreceptor, and to provide good image quality over a long period of time. This cleaning device is not limited to the organic photoreceptor, but can be applied to an a-Si photoreceptor, an Se-based photoreceptor, and any overcoated photoreceptor. However, the effect may differ depending on the physical characteristics and mechanical characteristics of the photoconductor, and the present invention is highly effective when an organic photoconductor is used. Organic photoreceptors can be manufactured at lower cost than photosensitive materials such as selenium and amorphous silicon, and have the advantages of easy production, no pollution, and high sensitivity. It is a photoconductor. However, since the organic photoreceptor is made of resin, the photosensitive layer is soft and has low mechanical durability (abrasion resistance). Therefore, when a two-stage cleaning blade system is used, abrasion resistance is disadvantageous depending on setting conditions. And the life of the photoconductor may be shortened. Therefore, when an organic photoreceptor is used, it is desirable to form a more wear-resistant coating layer on the photoreceptor. As a preferable method for the coating layer, a donor for improving the hole mobility in the same binder resin as the photosensitive layer (for example, a polycarbonate resin or a polyester resin) on the photosensitive layer, and further, if necessary, an antioxidant Alternatively, a plasticizer is added, and inorganic fine particles of titanium oxide or alumina are added to improve the abrasion resistance.
A resin to which about 40% is added is prepared, and a coating layer of 2 to 8 μm is formed by using a dip coating method, a spray coating method, or the like. Examples of the characteristics of the coating layer include electric resistances of 10 ¹² to 10.
¹⁴ Ω · cm, transmittance of 90% or more in the infrared region of 650 to 780 nm. As described above, by using the inorganic fine particles of titanium oxide or alumina, good electrophotographic characteristics can be maintained both electrically and in image quality. In addition, foreign substances adhering to the photoreceptor are easier to remove than a state without a coating layer. Therefore, the chargeability is high, the sensitivity is not reduced, and good image quality is provided. As described above, it is preferable to use a photoreceptor having a coating layer having a thickness of 2 to 8 μm in which inorganic fine particles are dispersed on the photosensitive layer. In this case, the inorganic fine particles forming the coating layer of the photoreceptor are preferably made of titanium oxide or titanium oxide. Advantageously, it is any of the aluminas.

With the above construction, the durability of the photoreceptor is greatly improved as compared with the conventional one, and sufficient characteristics can be maintained for a long time. However, if further improvement is desired, a lubricant is applied to the surface of the photoreceptor. It is desirable to add an appropriate amount of external additive to provide lubricity. There is also a method of internally adding a lubricant to the photosensitive layer,
It is not practical because it has no durability and its addition amount is limited. The lubricant reduces the frictional resistance between the cleaning blade and the developer and the photoconductor, so that abrasion of the photoconductive layer is suppressed. As the island-like thin film of the lubricant expands in the photosensitive layer, the bite by the carrier gradually decreases, and the filming caused by the toner, paper powder, and corona product is reduced.

Usable lubricants are fluororesins (polytetrafluoroethylene, polyvinylidene fluoride, etc.), zinc stearate, and the like. The lower the coefficient of friction after adding the lubricant, the more the wear of the photosensitive layer is suppressed, and High durability can be realized. However, if the friction coefficient is excessively reduced, paper dust and corona products adhered to the photoreceptor cannot be scraped, so that image deletion tends to occur, and the friction coefficient of the photoreceptor surface is set lower than 0.1. It is not preferable. The preferable range of the friction coefficient is 0.1 or more and 0.5 or less, and particularly preferably 0.2 or more and 0.4 or less. However, since it depends on the surface condition (uniformity) of the photoreceptor, the friction coefficient alone cannot sufficiently cope with it. However, if the friction coefficient is within the above range and the friction coefficient is low, the durability of the photoreceptor is low. It can be surely improved. The coefficient of friction of the photoreceptor surface when no lubricant is externally added is about 0.6 to 0.63. By setting the friction coefficient to fall within the above range, the durability of the photoreceptor can be realized from 200,000 to 400,000 or more. The friction coefficient is a numerical value when the Euler belt method is used, and will be described later. Another advantage of adding a lubricant is that the filming phenomenon caused by sticking of silica added to the toner as a fluidizing agent into the photoreceptor is gently and greatly reduced, and the appearance characteristics and, consequently, the deterioration of image quality are minimized. A hard stopping effect is recognized.

Hereinafter, the image forming apparatus will be described more specifically. 1) Copying process FIG. 1 schematically shows the image forming apparatus. The image forming apparatus shown here applies an image to a photoreceptor 1 rotating in a clockwise direction by using a charging roller 2 as shown, a charging brush (not shown), or a charging device 2 such as a corona discharge device. Surface potential required for formation, for example -400 to -1
000V. Next, in a digital image forming apparatus, an electric signal read or transmitted by a CCD (Charge Coupled Device) is transmitted to a polygon mirror, a cylindrical lens, and a dot by an LD or LED having a wavelength of 630 to 820 nm or less. 80-30 diameter
With the exposure device 3 using a convex lens for narrowing down to μm,
Image exposure is performed on the photoreceptor in the form of a dot pattern to form an electrostatic latent image. The electrostatic latent image thus obtained is visualized, that is, formed into a toner image by using the developing device 4 using a one-component or two-component developer, and the toner image is
Roller as shown, or belt shape not shown,
Alternatively, by any of the transfer devices 5 such as a corona discharge method,
Transfer to copy paper (plain paper) 9 as an example of a transfer material (9
The transfer paper is separated from the photoreceptor by the separating device. The copy paper 9 is conveyed to a fixing device 8, where the transferred toner image is fixed to form a hard copy. Since the developer (mostly toner) remains on the photoconductor after the transfer, the photoconductor is cleaned by the cleaning device 6.

As described above, the image forming apparatus shown in FIG. 1 charges a photosensitive member using a charging device, forms an electrostatic latent image by image exposure, and develops the electrostatic latent image by a developer. Then, the toner image on the photoconductor is transferred to a transfer material by a transfer device, and the residual toner on the photoconductor after the transfer of the toner image is removed by a cleaning device.

Here, the cleaning device 6 includes the photosensitive member 1
At least the first cleaning blade 10 in contact with
And a second cleaning blade 11. The first and second cleaning blades 10 are arranged such that the first and second cleaning blades 10 are in contact with a portion of the photoconductor surface upstream of the second cleaning blade 11 in the photoconductor surface movement direction. The first cleaning blade 10 is provided with respective blades.
Is composed of an elastic member to which a voltage can be applied as described above. Further, the cleaning device 6 is located downstream of the contact position of the first cleaning blade 10 with respect to the photoconductor with respect to the moving direction of the photoconductor surface, and the contact position of the second cleaning blade 11 with respect to the photoconductor. The cleaning brush 12 is in contact with the surface of the photosensitive member on the upstream side. The cleaning brush 12 is provided as needed, and the cleaning brush can be eliminated as in the cleaning device 6 shown in FIG. The image forming apparatus shown in FIG. 2 has the same configuration as that of the image forming apparatus except that the cleaning device 6 has no cleaning brush.
There is no difference from the image forming apparatus shown in FIG.

The first cleaning blade 10 which is closer to the transfer / separation device is installed by a counter or a leading system as shown in the drawing, and has a resilient material to which a voltage can be applied. The second cleaning blade 11, which is a conductive blade and is closer to the charging device, is constituted by a cleaning blade made of an elastic insulating material and installed in a counter system. The photoreceptor after the cleaning is erased by a static eliminator 7 (which does not necessarily require static elimination light) composed of an LED element of a long wavelength light, and the remaining electrostatic latent image in the photosensitive layer is erased, and the next copy cycle is started.

As described above, a charging device, an image exposing device, a developing device, a transfer device, and two cleaning blades are sequentially provided around the photosensitive member along the moving direction of the surface thereof, or Arrange a cleaning brush,
A cleaning device is provided so that a voltage can be applied to the first cleaning blade. As described above, by disposing a cleaning device incorporating two cleaning blades or a cleaning brush in the image forming apparatus, it is possible to provide a good image quality for a long time without ozone odor. On the other hand, since the photoreceptor at the time of image formation is released from contaminants, contamination of the photoreceptor and the charging member is reduced, and the durability of both members can be increased. The cleaning device can be used alone or incorporated in a process cartridge.

Although FIG. 1 shows a copying process using a single color developer, a tandem type image forming apparatus using four photosensitive members can be used even in a color type image forming apparatus using one photosensitive member. The apparatus basically uses the copying process shown in FIG. In addition, a belt-shaped or drum-shaped intermediate transfer body is used as a transfer material, and the toner image on the photoconductor is primarily transferred to the intermediate transfer body, and then the toner image is secondarily transferred to a final transfer material, for example, copy paper. Alternatively, the toner image may be fixed on the final transfer material. Further, as the photoconductor, a drum-shaped photoconductor as shown in the figure, or an endless belt-shaped photoconductor driven by being wound around a plurality of rollers can be used.

2) Photoconductor The photoconductor used in the above-described image forming apparatus can be basically any of inorganic photoconductors such as Se type and a-Si type and organic photoconductors. However, there is a difference in the appearance of the phenomenon depending on the photoreceptor, and it is necessary to wear the photoreceptor appropriately. Hereinafter, the organic photoconductor will be described in detail.

Organic photoreceptors have been used in recent years as the mainstream of photoreceptors, and have a high chargeability and can be designed with high sensitivity.
It has the advantages of being inexpensive, easy to produce by a spray method or dipping method, and having no pollution. On the other hand,
There is a problem that the durability is short because the hardness is low and brittle because it is made of resin. However, this durability can be improved by optimizing the copying system and the photoconductor configuration. The specific configuration of the photoconductor is shown in FIG.
The undercoat layer 1b and the charge generation layer 1 are sequentially formed on the conductive support 1a.
c, a photoconductor in which a charge transport layer 1d and a coating layer 1f are laminated. In this example, the charging polarity is negative. FIG. 4 shows a photoconductor having another configuration in which the charge generation layer and the charge transport layer are integrated, and the operation polarity is mainly positive. Hereinafter, the configuration of the photoconductor of FIG. 3 will be described.

Conductive Support The material of the conductive support is generally aluminum, which has been subjected to processing such as super finishing or mirror finishing, but it satisfies any of electrical, mechanical and chemical properties. If there is,
In addition to metals such as stainless steel, copper, and brass, conductive layers formed by depositing or sputtering gold, aluminum, platinum, chromium, etc. on compressed paper, resin, or glass, and conductive layers in which fine particles such as carbon and tin are dispersed. It may be coated. The electric resistance is a volume specific resistance of 10 ⁶ Ω
There is no problem if the value is less than cm order. The shape is, for example, a drum shape, and the thickness depends on the diameter and the material. When aluminum is used, a thickness of about 0.5 to 3 mm is used. 0.8- if the photoreceptor is 24-80 mmφ
A conductive support having a thickness of about 1.5 mm is used.

Undercoat Layer The undercoat layer is used to maintain charge characteristics by preventing charge injection from the conductive support, to prevent latent image disturbance due to irregular reflection in the photosensitive layer of digitally converted image exposure, and It is formed in order to improve the coating properties and adhesion of both the support and the charge generation layer. The undercoat layer is formed by dispersing a metal oxide such as TiO ₂ or SnO ₂ in an alkyd resin, an alkyd-melamine resin, polyvinyl alcohol, casein, or the like in the case of an alumina deposited film or a dispersion system on a conductive support. 1 using immersion method, spray method, ring coat method, etc.
Apply to a thickness of 10 μm. Preferably 4 μm to 8 μm
It is about. If the undercoat layer is too thick, the residual potential tends to increase repeatedly. If the undercoat layer is too thin, the SN ratio deteriorates, and noise (black spots, background stains, etc.) increases due to long use. Usually, by forming the undercoat layer having a volume resistance of about 10 ⁹ to 10 ¹² Ω · cm with a thickness of 3 to 8 μm uniformly, good electrophotographic characteristics can be maintained.

Charge Generation Layer The charge generation layer is obtained by dispersing a charge generation material in a binder resin. In the case of an organic photoreceptor, as a charge generating material, metal phthalocyanines, phthalocyanines such as metal-free phthalocyanines, azo pigments having a skeleton such as carbazole, triphenylamine, fluorenone, and oxadiazole, perylene pigments, and quinones such as anthranthrone Pigments, perylene pigments, benzoquinone and naphthoquinone pigments, polycyclic quinone pigments, quinone imine pigments and the like can be used alone or as a mixture of two or more. Moreover, you may add a low molecular transport substance as needed. As the binder resin, a polyamide resin, a polyester resin, a polycarbonate resin, a polyurethane resin, an acrylic resin, a polyacrylamide resin, a phenol resin, or the like can be used.
Further, as a hole-transport substance, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, thiazole derivatives, triazole derivatives, styryl anthracene,
Styrylpyrazoline and the like are used alone or in combination of two or more. These charge generating materials and binder resins are dispersed uniformly in a ball mill, a sand mill, a vibration mill, or the like using tetrahydrafuran, toluene, cyclohexanone, dichlorethane, or the like as a dispersion, and spray coating is performed.
Using a dipping method or the like, the undercoat layer is coated with a thickness of 0.05 to 5 μm, preferably 0.2 to 1 μm. If the thickness is more than necessary, the space charge increases, which affects the light attenuation characteristics, the residual potential, and the like.

Charge Transport Layer The charge transport layer is obtained by dispersing a charge transport material in a binder resin. Oxazole derivatives, oxadiazole derivatives (described in JP-A-52-139065 and 52-139066), imidal derivatives,
Triphenylamine derivatives (described in Japanese Patent Application No. 1-77839), α-phenylstilbene derivatives (described in Japanese Patent Application Laid-Open No. 57-73075), and toniphenyl methane derivatives (described in Japanese Patent Application No. 51-10983) And anthracene derivatives (described in JP-A-51-94829) can be used. As the binder resin, a polycarbonate resin (bisphenol A type, bisphenol C type, bisphenol Z type or a copolymer thereof), a polyarylate resin, a polyester resin, a polystyrene resin, a vinyl acetate resin, or a mixture of two or more kinds may be used. Can be done.

In order to improve environmental resistance, an antioxidant can be added to suppress a decrease in sensitivity and a rise in residual potential. Examples of the antioxidant include monophenolic compounds such as 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, and 2,6-di-t-butyl-4-ethylphenol. '-Methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-
Bisphenyl-based compounds such as ethyl-6-t-butylphenyl), 1,1,3-tris- (2-methyl-4-hydroxy-
5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-
High-molecular-weight phenolic compounds such as 4-hydroxybenzyl) benzene and tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane 2,5-di-t Hydroquinones such as -octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, and 2- (2-octadecenyl) -5-methylhydroquinone.

The thickness of the charge transport layer is desirably set to a uniform range of 5 to 30 μm. Setting the thickness to about 10 to 25 μm is advantageous for forming an electrostatic latent image having a high resolution of 600 to 1200 dpi or more. Since the resolution of the copy image is also affected by the toner, the particle size of the carrier, the developing method, the dot system of the original image, the transfer conditions, the surface resistance of the charge transport layer, the bulk resistance, etc., the resolution of the electrostatic latent image can be achieved. It is desirable to set only a high level. The resolution of the electrostatic latent image on the photoreceptor tends to gradually decrease as the film thickness increases, because light and charges diffuse as the photosensitive layer becomes thicker. Therefore, a thinner thickness of the charge transport layer is advantageous in terms of resolution, but as the thickness becomes thinner, since the photosensitive layer is a dispersion layer, non-uniformity of electric resistance becomes conspicuous, and in the long term, Decreases the SN ratio and decreases the electrical durability,
A problem such as a down without waiting for mechanical durability occurs. Further, by reducing the thickness of the charge transport layer, the contrast potential required for image formation cannot be obtained, and an image having low contrast and gradation is obtained.

Coating Layer The coating layer is formed on the photosensitive layer in order to improve the mechanical and electrical durability of the photoreceptor.
Thin films such as amorphous silicon film and high resistance tin oxide film
About 5 μm, a method of forming by vacuum evaporation, CVD, sputtering, ion plating, etc., 0.0
Fine particles of about 5 to 5 μm are dispersed in a binder resin,
There is a method of coating a thin film on the photosensitive layer. By dispersing an appropriate amount of the inorganic fine particles in the binder resin, the durability of the photoconductor can be improved. As the inorganic fine particles, there are titanium oxide, silica, alumina, zirconium oxide, indium oxide, silicon nitride, and the like. Particularly, alumina and titanium oxide have good environmental stability in order, and can be used as suitable inorganic fine particles. . These inorganic fine particles can be subjected to a water-repellent treatment using a silane coupling agent or a fluorine-based silane coupling agent. Inorganic fine particles of polycarbonate resin as a binder resin, polyethylene resin, polyurethane resin, acrylic resin, but can be distributed and used in the polyamide resin, preferably a polar dependency no 10 ^16-10 good transparency
A polycarbonate resin having a high resistance of about ¹⁷ Ω · cm is preferable.

When dispersing inorganic fine particles in a binder resin, by dispersing an appropriate amount of fine particles of a fluorine-based resin such as polytetrafluoroethylene, water repellency and lubricity are enhanced, and environmental characteristics and wear resistance are improved. Is also possible. The dispersion amount of the inorganic fine particles is 25 to
It is preferable to add about 40% by weight, and when the addition amount is large, the abrasion resistance is increased, but on the other hand, the light transmittance is decreased, the diffusion, the charge mobility is decreased, the resolution is reduced, the residual potential is increased, and the like. The sensitivity is likely to decrease. In addition, contaminants which hinder image formation, such as filming due to corona products or toner components attached to the surface, may be less likely to be worn and may cause a reduction in resolution. On the other hand, when the addition amount of the inorganic fine particles is small, the friction coefficient becomes high, mechanical durability cannot be maintained, toner filming due to the developer, adhesion of silica or the like (sticking), and the like are likely to occur. Dots and unevenness may occur. Therefore, the thickness of the coating layer depends on the required durability, but is in the range of 2 to 8 μm, preferably 3 μm.
It is desirable to set it to about 6 μm.

Since inorganic fine particles are dispersed in the coating layer, if there is any deviation or poor dispersion of the particle size, the resolution, residual potential, mechanical durability and the like are affected. Therefore, it is desirable that the inorganic fine particles in the coating layer are substantially uniformly dispersed in the layer. The total thickness of the photosensitive layer including the photosensitive layer (= charge generation layer + charge transport layer) and the coating layer is desirably set in the range of 15 to 30 μm.

3) Charging Method and Apparatus Charging prior to the formation of an electrostatic latent image on a photoreceptor and a charging method for transferring a toner image to copy paper include a corona discharge method and a charging member such as a charging roller or a brush. The contact or non-contact charging method or the like is used. In the corona discharge method, an absolute value of 4000-80 μm is applied to a 40-80 μm tungsten wire or a saw-toothed SUS plate mounted in a metal case.
A method of applying a high voltage of 8000 V. Since a high voltage is applied, corona products such as ozone and nitrogen oxides are inevitably increased in comparison with a low-voltage driven contact charging method, which causes environmental problems. . The corona discharge method (mainly a scorotron charger) does not damage the photoreceptor because it is non-contact, and it is easy to uniformly charge it by operating it about 10 cm away from the photoreceptor. The generated corona product flies toward the photoreceptor For example, it is possible to reduce the chemical influence of the corona product on the photoreceptor by using the contact charging method. However, a large amount of ozone and nitrogen oxides are generated, and there are many environmental problems.

On the other hand, the contact charging method and 50-250 μm
In the non-contact charging method in which charging is performed from a charging member that is installed at a certain distance, a DC voltage or a sine-wave AC voltage (1000 V to 2000 V in absolute value, 500 Hz to 2.
5 KHz) is applied so as to be superimposed on the DC voltage, and is charged so that the surface potential becomes about 400 to 800 V in absolute value.
Since the applied voltage is low, the amount of corona products such as ozone and nitrogen oxides is extremely small at 1/100 or less of that of the corona discharge method. Therefore, the exhaust treatment device may be simple, and there is almost no environmental problem. However, even if the amount of production is very small,
The effect of the corona product on the photoreceptor is large, and presents significant problems in image quality, such as reduced resolution, image deletion, and uneven density of a halftone image. The merit of the method in which the charging member is slightly separated from the photoconductor and charged is advantageous in that even if the charging member is soiled, damage to the photoconductor is reduced.

Since this corona product adheres extremely thinly to the photoreceptor, it is not easy to remove it with a cleaning blade, and the photoreceptor having higher abrasion resistance cannot be more easily removed. Therefore, a cleaning method for cleaning the photoreceptor surface is extremely important. As the charging method used in the present invention, any of the above-mentioned methods can be used. However, a non-contact charging method in which charging is performed in contact or in close proximity is preferred from environmental characteristics. As described above, as a means for charging the photoconductor, a contact charging device or 50 to 25
By using a non-contact charging member that is disposed about 0 μm away from the photoreceptor and performs charging, power saving and downsizing of the power supply device are achieved as compared with the related art, and the generation of ozone is minimized. Environmentally favorable. When a non-contact charging member is used, dust or the like that adheres to the photoreceptor is unlikely to adhere, so that the durability of the charging member can be further increased. An electric charge required for image formation is applied to the photoreceptor by a charging device including a conductive member that is in contact with or very close to the photoreceptor to form an image. For example, as shown in FIG.
For example, the charging device 2 including a charging roller having an elastic layer having a volume resistivity of 10 ^{5 to} 10 ⁸ Ω · cm is used.

4) Cleaning Device The cleaning device includes not only toner but also a corona product,
This device removes as much as possible pollutants such as paper dust and filming, which are problematic in image formation. The cleaning device 6 shown in FIG. 1 uses first and second two cleaning blades 10 and 11 and a cleaning brush 12, and the cleaning device 6 shown in FIG. 2 does not use a cleaning brush. The material of the first cleaning blade close to the transfer / separation device is preferably urethane rubber, but BSR, CR, silicone rubber and the like can also be used. These carbon powders in the rubber material, the addition of materials such as carbon and an alkali metal salt, a volume resistivity of 10 ⁰
~10 ⁸ Ω · cm, one in which the form and the hardness of 50 to 80 degrees. The thickness of the blade can be used in about 1.5-4mm,
Usually, it is around 2 mm. The first cleaning blade 10 may be installed on the photoreceptor 1 by a counter or a reading method, but is preferably installed by a reading method, and the contact pressure is set lower than that of the second cleaning blade 11. For example, if the contact pressure of the second cleaning blade is set to 60 to 80 mN / cm, the contact pressure of the first cleaning blade is set to 60 mN / cm or less. This is because if the amount of toner and paper dust is large, the photoreceptor is likely to be damaged. By applying a voltage, the toner can be set at a low level. Can be complemented by When the cleaning performance of the cleaning device is improved, the charging roller is not contaminated, the charging property is stabilized, and the image quality can be maintained high. The application of a voltage to the first cleaning blade 10 or the grounding of the blade 10 facilitates removal of paper dust, toner, and the like attached to the photoconductor.
As shown in FIGS. 1 and 2, any one of ground, a DC voltage, an AC voltage, and a DC voltage on which an AC voltage is superimposed can be selected according to use conditions. 1 and 2, reference numeral 14 denotes a DC power supply, and reference numeral 13 denotes an AC power supply.
The voltage applied to the first cleaning blade 10 is about 200 to 800 V DC, and 200 to 1000 AC.
V, the frequency is a sine wave of about 50 to 2000 Hz.

The second cleaning blade 11 attached to the charging device side is provided with urethane rubber on the counter, so that the toner paper powder and the corona generated from the first cleaning blade 10 are sufficiently removed. If the first cleaning blade 10 is working sufficiently,
The contact pressure of the cleaning blade 11 can be made lighter than that of a single-unit cleaning device, so that the durability of the blade can be extended.

The material of the cleaning brush provided between the first and second cleaning blades is, for example, a fiber such as polypropylene, polyethylene, nylon or the like having a fiber thickness of 15 to 20 deniers applied to a resin roller with a density of 2,000.
Approximately 3500 hairs / inch ² are planted and processed into a brush-like roller for use.

The reason for installing the cleaning brush is particularly effective in a high-speed copying machine or when a large amount of corona product is generated. That is, high-speed copying machines often use highly durable photoconductors, and contaminants such as paper dust and corona products increase according to the copying speed and the number of sheets. Therefore, there are cases where two cleaning blades are insufficient. Since the cleaning brush cleans the contaminant adhering to the photoreceptor by scraping it off at the tip of the brush, the cleaning property is more reliably improved than when the blade is used alone. Of course, this method can be sufficiently used for an image forming apparatus having a copying speed of about 20 to 40 sheets. By using a series of these cleaning devices, it is possible to almost eliminate contaminants that reduce the image quality on the photoreceptor, and to provide good image quality over a long period of time.

5) Method of Externally Adding Lubricant The reason for supplying the lubricant onto the photoreceptor is, as described above, deterioration of the photoreceptor appearance, for example, toner filming, penetration of a developer additive component such as silica into the photoreceptor. It is to avoid the effects of, but by suppressing the above phenomenon,
The lubricant easily acts on the photoconductor, which contributes to the reduction of the friction coefficient of the photoconductor. As a method of supplying the lubricant to the photoconductor, there is a method of directly or indirectly supplying a powdery or block-shaped lubricant to the photoconductor. For example, powdery zinc stearate, PTFE (polytetrafluoroethylene resin), polyfukkavinylidene, or the like is added to the developer at a ratio of 0.01 to 0.5% based on the toner. If too much is added, the friction coefficient of the photoreceptor may be too low, or the physical properties (for example, Q / M) of the toner may be violated, the control may not be effective, and the toner may be excessively supplied. Usually, it is desirable to add 0.01 to 0.3% to the toner. The amount of the lubricant to be added is sufficient to suppress filming and poor appearance due to toner. Incidentally, when the lubricant is used alone (when the surface property adjusting member is not used in combination), the amount of addition is only such an amount that the friction coefficient of 0.6 is reduced to about 0.45 to 0.55. . Therefore, there is almost no effect in suppressing abrasion of the photosensitive layer. The method of supplying the solid lubricant is a member to be worn,
For example, there is a method in which a dedicated brush or a cleaning brush (fur brush) is also used. In this method, a block-shaped lubricant is supplied to a photoreceptor while being worn by a brush.
The amount of supply is controlled by lightly contacting the lubricant with the brush. Still another supply method is 50-
There is a method in which a film-like lubricant of about 200 μm is supplied in contact with the photoconductor. This method can reduce the friction coefficient by controlling the pressure of the lubricant that comes into contact with the photoreceptor, or by switching to another fluororesin.

6) Coefficient of friction The coefficient of friction is an important characteristic in improving the mechanical durability of the photosensitive layer. The friction coefficient of the photoreceptor can be reduced to 0.1 by adding a leveling agent (eg, silicone oil).
It is about 3 to 0.5 (value measured by the Euler belt method described later), and is 0.6 or more when the leveling agent is not added. However, even when a leveling agent is added, if about 20 copies are made, the coefficient of friction immediately exceeds 0.6, and there is no durability. When a photoreceptor without such a coating layer is used, the abrasion of the photosensitive layer is increased due to abrasion by a cleaning blade or a developer, and durability cannot be maintained. Further, the above-described adhesion of silica or piercing may occur, which may cause uneven filming or uneven wear on the surface of the photoreceptor. The inorganic fine particles in the coating layer form irregularities on the surface layer of the photosensitive layer, and reduce frictional resistance with the cleaning blade. 30% inorganic fine particles
The coefficient of friction when added to a certain degree is about 0.4 to 0.6, which is relatively persistent unlike the case without a coating layer, so that wear is reduced in combination with fine particles of high hardness. By reducing the coefficient of friction, the pressure of the cleaning blade, the developer, the contact charging device, etc., which is in contact with the photoconductor, is reduced, so that the wear of the photosensitive layer is necessarily reduced. However, if the friction coefficient is too low, the cleaning performance by the cleaning blade is significantly reduced, so that it is difficult to remove contaminants such as corona products, paper dust, and filming, and image quality such as resolution degradation and image deletion is reduced. Is generated. The preferable range of the coefficient of friction is 0.1 or more and 0.5 or less, and preferably 0.2 to 0.4. When the value is around 0.6 or more, the wear of the photosensitive layer is accelerated, but the wear may be affected by the surface condition of the photoconductor. The method of externally adding a lubricant to a photoreceptor is to use a powdery, solid, or film-like fluororesin, zinc stearate, a liquid lubricant such as silicone oil or a fluorine-based oil, or a gaseous lubricant. There is a method of adding a small amount of a lubricant to a developer, in addition to a method of causing a photoreceptor to act as an external addition method.

When the coefficient of friction of the surface layer of the coating layer is reduced by using a film-like fluororesin, it is 100 to 400 μm.
A lubricating member is prepared using a fluorine-based resin (for example, PTFE = polytetrafluoroethylene) film having a thickness of about m and an elastic member for softly contacting the photosensitive member, and the member is coated on the surface of the coating layer. By pressing uniformly, the coefficient of friction can be reduced. Depending on the pressing of the lubricity imparting member against the photoreceptor, there is a possibility that abrasion may occur on the photoreceptor, but the inorganic fine particles are dispersed, and the friction coefficient is lightly adjusted to be around 0.4. If they come into contact with each other, almost no scratch is given to the image.
Further, when a lubricant such as fluorine resin fat or zinc stearate is used, the lubricant can be once attached to a coating member such as a brush and then supplied to the photoreceptor from the coating member. Furthermore, powdery fluororesin (PTF)
When E) is supplied to the photoreceptor, it can be attached to a feather or a cotton-like material and supplied little by little to the surface of the coating layer. There is an intermittent method of supplying to the coating layer surface continuously or at regular intervals, but if the coefficient of friction is too low, the mechanical durability can be greatly extended. Too much damage may cause adverse effects such as image deletion.
It is preferable to perform the printing in an intermittent manner such that the printing operation is performed once for one sheet. When a lubricant is added to the toner, for example, zinc stearate and powdery fluororesin are used in the toner in an amount of about 0.01 to 0.4%, preferably 0.1 to 0.2%.
%. If the amount of addition is large, the coefficient of friction is significantly reduced while copying proceeds, leading to image deletion.

The coefficient of friction is calculated by the following measuring method. FIG.
As shown in FIG. 6, a photoconductor 1 for measurement is fixed to a pedestal, and a high-quality paper [thickness of 85 μm cut into a width of 30 mm and a length of 297 mm, for example] [type 62 manufactured by Ricoh Co., Ltd.
00 paper, longitudinal stitches] is prepared as a belt 24, and the belt 24 is wrapped around the peripheral surface of the photoreceptor 1 at an angle of 90 °, and is wrapped around one end of the belt via a yarn 20 of negligible weight and 100 gr. A weight 25 is attached, and a digital force gauge 23 for weight measurement is attached to the other end via a thread 21 with negligible weight. The digital force gauge 25 placed on the table is slowly pulled in the direction of arrow A, and the weight at which the belt 24 starts to move by sliding on the photoreceptor is read, and the (static) friction coefficient is calculated by the following equation. . μs = 2 / π × ln (F / W) where μs: coefficient of static friction, F: reading load W: weight of weight π: pi The method of measurement (Euler-belt method) is disclosed in
166919 and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

EXAMPLES <Method of Manufacturing Photoconductor for Evaluation> A photoconductor was manufactured in the following manner. A coating liquid for an undercoat layer (UL), a coating liquid for a charge generation layer (CGL), and a coating liquid for a charge transport layer (CTL) on an aluminum drum having a diameter of 60 mm, a length of 340 mm, and a thickness of 1.2 mm. , Followed by dip coating, followed by heating and drying to give a 3.5 μm undercoat layer, 0.15
A charge generating layer having a thickness of about 0.2 μm and a charge transporting layer having a thickness of 22 to 25 μm were applied to prepare a photoreceptor. Further, a binder resin, a donor, inorganic fine particles (metal oxide) and a solvent were placed on the photoreceptor in a glass pot, and dispersed in a ball mill for 24 hours to obtain an average particle diameter (measured by a CAPA500 manufactured by Horiba, Ltd.) of about 0.45 to about 0.45. A coating liquid of 0.55 μm is prepared, and is applied 1 to 3 times (approximately 1.5 to 2.0 μm /
Times) and dried by heating to form a coating layer of 1 to 10 μm, thereby completing an electrophotographic photosensitive member. All parts described below represent parts by weight.

[Coating solution for undercoat layer] Alkyd resin (Beccosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals, Inc.) 6 parts Melamine resin (Super Becamine G-821-60, Dainippon Ink and Chemicals 4 parts Titanium oxide (CR-EL manufactured by Ishihara Sangyo Co., Ltd.) 40 parts Methyl ethyl ketone 200 parts [Coating liquid for charge generation layer] Oxo titanium phthalocyanine pigment 2 parts Polyvinyl butyral (UCC: XYHL) 0.2 parts Tetrahydrofuran 50 Part [Coating liquid for charge transport layer] Bisphenol A type polycarbonate (Z-Polyka manufactured by Teijin Chemicals Limited) 10 parts Low molecular charge transport material having the following structure 12 parts

Embedded image Methylene chloride 100 parts Methyl phenyl silicone oil (50 cs) 1 part [Coating liquid for inorganic fine particle layer] The coating liquid for inorganic fine particle layer is 25% by weight of binder resin and inorganic fine particles, and the ratio of charge transport material to binder resin. And 7 to 1/10 by spraying using cyclohexanone as a solvent.
Spraying was performed four times to form four kinds of coating layers. Binder resin: Polycarbonate resin (Z polycarbonate, Mv50,000 manufactured by Teijin Chemicals Ltd.) Inorganic fine particles: Alumina powder (AA-40 manufactured by Sumitomo Chemical Co., Ltd.) Low molecular charge transport material: The following structure

Embedded image Solvent: cyclohexanone

<Charging member> Epichlorohydrin rubber in which carbon was uniformly dispersed was applied to a rod rod made of brass having a thickness of 8 mm, and was formed to a thickness of 14 mmφ with an electric resistance of 2 to 6 × 10 ^5.
As a charging member of Ω · cm (when 100 VDC was applied), a charging member processed so as to be separated by 100 μm in an image forming area of the photoconductor was prepared. 60μ thickness on both ends of charging member
A single layer of PET (polyethylene terephthalate) having a width of 10 mm and a width of 10 mm was adhered and processed so as to have a void in the image forming area when it was brought into contact with the photoreceptor. In addition, the space | gap when arrange | positioned facing a photoreceptor was 85-100 micrometers. This charging member was used by being set in a housing.

<Cleaning Device> A cleaning device for a single cleaning blade having a 2-mm-thick urethane rubber attached thereto by a counter method. The first cleaning blade has a thickness of 2 mm, an electric resistance of 2 to 5 × 10 ⁶ Ω · cm, and a hardness of 60. The urethane rubber (made by Kinugawa Rubber) is used as shown in FIG. 2 and is attached by a reading method as shown in FIG. 2, and a urethane rubber having a thickness of 2 mm is used as a second cleaning blade. Cleaning equipment installed,
2500 fibers / i of 17 denier polypropylene fiber
As shown in FIG. 1, three types of cleaning devices were prepared, in which a cleaning brush having a diameter of 30 mm implanted (straight hair) at a density of nch ² was attached between two cleaning blades. The motor for driving the cleaning brush was externally mounted, and was set so as to rotate in the forward direction with the rotation of the photoconductor as shown in FIG. The rotation speed is 17
It was set to 0 rpm.

<Evaluation Method> The evaluation image forming apparatus
A cleaning device having a single cleaning blade configuration,
A cleaning brush and two cleaning blades
Cleaning device consisting of two cleaning blades
So that a cleaning device consisting of
Experimental electronics with copy speed 28 (sheets / min)
A photocopier was prepared. The developer has a particle size of about 9.5 μm.
Cyan toner (SiO 2 as a fluidizing agent) ₂= 0.7%, Ti
O₂= 0.8%, lubricant (SZ2000) = 0.05%
Addition) with a magnetic carrier (FPC-30) having a particle size of 80 μm.
0LC) 5% concentration developer (Ricoh prototype development)
Agent) was used. The gap between the charging member and the photosensitive member is 85 to 1
Made of epichlorohydrin rubber with a carbon dispersion of 00 μm
Using a charging roller of φ14 mm, the applied voltage
The alternating voltage is superimposed on the charging member with a high-voltage cable from the power supply
DC voltage was applied. The voltage condition is an alternating voltage of 1.5 KV
/ 1KHz, DC voltage is -600V at the surface potential of the photoreceptor
It was adjusted to be. Note that a high voltage applied voltage for the charging member is used.
The source is Yokogawa's function generator FG-30
0 + trigger voltage using Nagano Aichi Electric HV-255
The timing of voltage application to the photoreceptor was planned.

Evaluation items were in a normal humidity environment (22 ° C./55% R).
H), the resolution after the paper passing running, the photoconductor appearance,
The coefficient of friction is the resolution and image quality when the image is formed after the image forming apparatus is left at 30 ° C./90% RH for 3 hours after the humidity control, that is, after the paper passing running. “After run” in the table means after running. Although not shown in the table, the wear amount of the photosensitive layer was also evaluated. The wear amount of the photosensitive layer was measured using an eddy current film thickness meter (Fisher scope MMS) manufactured by Fischer, and the film thickness was measured at 26 points before and after running, and the average value was determined. The friction coefficient was measured using a self-made device and a 30 mm x 297 mm high quality paper (Ricoh type 6)
200 paper, vertical), 100g weight, digital
Using a force gauge (FGC-2 manufactured by Shinpo Kogyo Co., Ltd.), the measurement was performed by the above-described Euler belt method. The image quality is determined by using a standard test chart and a JIS standard bamboo shoot chart attached to the original as a document to determine the resolution, sharpness, etc., and using a 5% line chart for the running paper. 100,000 sheets were evaluated at a rate of 99 sheets per cycle.

(Example 1) Thickness 2 mm, hardness 60 degrees, electric resistance 2-5 × 10 ⁶ Ω · cm, contact pressure 45, 55,
A cleaning device comprising a first cleaning blade of 70 mN / cm and 85 mN / cm, a second urethane rubber cleaning blade having a thickness of 2 mm and a contact pressure of 75 mN / cm was mounted on an experimental electrophotographic copying machine. The voltage applied to the cleaning blade 1 is grounded (0 V),-
500VDC, 1200VAC / 1000Hz, +30
Four conditions of 0 VDC + 1200 VAC / 1000 Hz were set. Charge transport layer (CTL) 23 μm as photoreceptor,
A coating layer having a thickness of 5.0 μm was prepared.
As the developer, a toner (manufactured by Ricoh) containing 0.05% of zinc stearate added to the toner was used. The results are shown in Table 1 to Table. The contact pressure of the first cleaning blade is 55, 7
When set to 0 mN / cm, there was no problem with the image quality of the photoconductor, but at 45 and 85 mN, the photoconductor was slightly or slightly scratched or filmed. Did not. Under the conditions of the voltage applied to the first cleaning blade, better results were obtained under conditions involving an AC voltage, but under other conditions, by setting the conditions to suitable conditions, it was possible to obtain satisfactory quality. Can be set. Abrasion of photoreceptor is 0.08 to 0.12
μm / 10,000 sheets, and durability equivalent to 300,000 to 400,000 sheets was confirmed.

[0061]

[Table 1]

(Comparative Example 1) The cleaning device was changed to a device having one cleaning blade, the contact pressure of the blade was set to 75 mN / cm, and zinc stearate 0% and 0.05% were added to the developer. The organic photoreceptor having the same coating layer of 5 μm as in Example 1 was used as the photoreceptor. Table 2 shows the evaluation results. Comparative Examples 1-1 and 1-
2 is 0% zinc stearate, and Comparative Examples 1-3 and 1-4 are 0.05%. The method of forming filming is lighter when zinc stearate is added, and the degree of image deletion is locally limited. However, a cleaning device including one cleaning blade removes contaminants on the photoconductor. However, after 100,000 sheets, a problem may occur in image quality.

[0063]

[Table 2] (Embodiment 2) The cleaning device was replaced with a cleaning brush having a cleaning brush mounted between the first and second cleaning blades, and the contact pressure of the first cleaning blade was reduced to 45,5.
5, 70, and 85 mN / cm, and the contact pressure of the second cleaning blade was set to 75 mN / cm. An organic photosensitive material equivalent to that of Example 1 having a coating layer of 5 μm in which a developer is made of zinc stearate of 0.05% with respect to the toner and 30% of alumina (AA-40) with respect to the binder resin is added to the photosensitive member. Used body. Table 3 shows the evaluation results. When cleaning brush is added, contact pressure is 85m
Except for removing N / cm, very good results were obtained.
The coefficient of friction was about 0.3 as a whole, and the fogging was not so much as to cause a streak mainly at the end. The wear of the photosensitive layer was slightly higher than that of Example 1, and wear of 0.1 to 0.17 μm / 10,000 sheets was confirmed.

[0064]

[Table 3]

(Example 3) A cleaning device in which two cleaning blades were arranged was prepared, and an AC voltage of 0 V, 1100 V / 1 KHz was applied to the first cleaning blade, and the contact pressure was set to 45, 55 and 70mN / c
m, and the contact pressure of the second cleaning blade is 65 m
N / cm was set. The properties were evaluated by using a developer in which 0.05% of zinc stearate was added to the toner and an organic photoreceptor having no coating layer formed on the photoreceptor. Table 4 shows the results. Even if the photoconductor does not have a coating layer, by reducing the contact pressure of the cleaning blade,
The occurrence of scratches could be reduced, and the image quality was good. The abrasion of the photosensitive layer was 0.2 to 0.4 μm / 10,000 sheets because no coating layer was formed.

[0066]

[Table 4]

(Comparative Example 2) A cleaning device having a single cleaning blade was prepared and the contact pressure was set to 65 m.
N / cm was set. A developer prepared by adding 0% and 0.05% of zinc stearate to the toner is provided.
An organic photoreceptor without a coating layer was used as the photoreceptor, and the characteristics were evaluated. Comparative Example 2-1 and Comparative Example 2
-2 is 0% zinc stearate, and Comparative Examples 2-3 and 2-4 are 0.05%. Table 4 shows the results. In a cleaning device including a single cleaning blade, filming caused by fixing of contaminants such as toner, paper powder, and corona products appears from silica or the like pierced on the surface of the photoreceptor. There were problems such as uneven density and reduced resolution. Abrasion of the photosensitive layer tends to be mitigated when using a toner to which zinc stearate is added.However, since filming has occurred more or less, the apparent abrasion is small,
Some sites increased in some places.

[0068]

[Table 5]

Example 4 Using a cleaning device having two cleaning blades, the contact pressure of the first cleaning blade was varied to 45, 55, and 70 mN / cm, and the applied voltage was changed to 1400 V / 1 KHz. The voltage was set. The contact pressure of the second cleaning blade is 75
It was set to mN / cm. The photoreceptor has a coating layer thickness of 2,
Three types of photoreceptors having variable sizes of 5 and 8 μm were used, and a developer obtained by adding 0.1% of zinc stearate to the toner was used. Evaluation was performed based on these factors. Table 6 shows the results. For the photoreceptor having a coating layer of 8 μm, the image density decreased due to the decrease in the residual potential, but the appearance of the photoreceptor was good. Regarding the photoconductors of 2 μm and 5 μm, even if the contact pressure is varied between 55 and 70 mN / cm, no clear abnormal phenomenon is observed in both the photoconductor appearance and image quality, and the first
Even if the contact pressure of the cleaning blade was as low as 45 mN / cm, there was no problem with the image quality and the photoreceptor.
In the case of a photoreceptor having a coating layer of 2 μm, the photosensitive layer was cut off by 1.5 μm on 100,000 sheets, so that the durability is considered to be about 100,000 sheets, but no abnormal image was confirmed even on 100,000 sheets.

[0070]

[Table 6]

[0071]

According to the first aspect of the present invention, at least two cleaning blades are provided as means for releasing contaminants unnecessary for image formation, such as toner, paper dust, and corona products, remaining on the photoreceptor. By adopting a member capable of applying a voltage to the first cleaning blade and setting appropriate voltage conditions including grounding according to a use condition, cleaning with a finer grain than in the related art can be achieved.

According to the second aspect of the present invention, the first cleaning blade is grounded, or one of a DC voltage, an AC voltage, and a DC voltage obtained by superimposing an AC voltage is selected and applied as the applied voltage. As a result, the contaminants remaining on the photoconductor can be efficiently removed in combination with the rubbing force of the cleaning blade itself.

According to the third aspect of the present invention, even if the surface of the photoreceptor enters the first cleaning blade in a state where a large amount of toner and paper dust remain, the photoreceptor can be scratched,
A problem that causes filming can be suppressed. Meanwhile, the first
Since most of the toner is removed by the cleaning blade, even if the contact pressure of the second cleaning blade with respect to the photoreceptor is slightly increased, scratching hardly occurs.

According to the fourth aspect of the invention, by further disposing a cleaning brush between the first cleaning blade and the second cleaning blade, minute contaminants such as corona products can be eliminated, and the surface of the photosensitive member can be removed. Is further purified, so that deterioration of image quality is suppressed even in a high-humidity environment, and good image quality can be provided over the entire environment.

According to the fifth aspect of the present invention, by providing an optically and electrically good wear-resistant coating layer on the photoreceptor, the durability of the photoreceptor can be extended.
If the coating layer is thinner than 2 μm, the durability cannot be maintained, and if it is thicker than 8 μm, the durability increases, but a problem arises in image quality due to an increase in residual potential. Providing a coating layer of inorganic fine particles also has the advantage of reducing the adhesion of foreign matter on the photoreceptor.

According to the invention of claim 6, by externally adding a lubricant to the surface of the photoconductor so as to lower the friction coefficient of the surface of the photoconductor, abrasion of the photoconductor can be suppressed.
Due to the action of the lubricant, the adhesion of contaminants to the photoreceptor can be suppressed, so that the durability of the photoreceptor can be lengthened, and a good image can be formed over a long period without reducing the image quality. You can do it.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus.

FIG. 2 is a schematic view illustrating another example of the image forming apparatus.

FIG. 3 is an enlarged cross-sectional configuration diagram of a photoconductor.

FIG. 4 is an enlarged cross-sectional configuration diagram of another photoconductor.

FIG. 5 is a diagram illustrating an Euler belt system.

FIG. 6 is a diagram of the photoconductor and the belt viewed in a direction indicated by an arrow VI in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 5 Transfer device 6 Cleaning device 9 Transfer material 10 1st cleaning blade 11 2nd cleaning blade 12 Cleaning brush

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Adult Kojima 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H068 AA04 CA33 2H134 GA01 GB02 GB05 GB06 HB00 HD01 HD03 HD06 HD11 HD14 HD15 HD19 KD05 KD12 KG08 KH01 KH05 KH15 LA01 QA02

Claims (6)

[Claims] 1. A photoconductor is charged by using a charging device,
After forming an electrostatic latent image by image exposure, developing the electrostatic latent image with a developer to form a toner image, the toner image on the photoconductor is transferred to a transfer material by a transfer device, and the toner image is cleaned by a cleaning device. An image forming apparatus for removing residual toner on a photoconductor after transfer, wherein the cleaning device has at least a first cleaning blade and a second cleaning blade that are in contact with the photoconductor, and the first cleaning blade is a first cleaning blade. The first and second cleaning blades are respectively provided so as to abut on the photosensitive member surface portion upstream of the photosensitive member surface movement direction with respect to the second cleaning blade, and the first cleaning blade is constituted by an elastic member to which a voltage can be applied. An image forming apparatus, comprising: 2. The image forming apparatus according to claim 1, wherein the first cleaning blade is grounded, or is applied with a DC voltage, an AC voltage, or a DC voltage having an AC weight. 3. The image forming apparatus according to claim 1, wherein the contact pressure of the first cleaning blade against the photoconductor is set lower than the contact pressure of the second cleaning blade against the photoconductor. 4. The cleaning device according to claim 1, wherein the first cleaning blade is located downstream of a contact position of the photoconductor with respect to a moving direction of the photoconductor surface, and a contact position of the second cleaning blade with respect to the photoconductor. The image forming apparatus according to claim 1, further comprising a cleaning brush that comes into contact with a portion of the photoreceptor surface upstream of the image forming apparatus. 5. A photoconductor having a coating layer having a thickness of 2 to 8 μm in which inorganic fine particles are dispersed on the photoconductive layer.
The image forming apparatus according to any one of claims 1 to 4. 6. Lubricity is imparted by applying a lubricant to the photoreceptor surface by an external addition method, and the coefficient of friction of the photoreceptor surface is reduced to 0.1.
The image forming apparatus according to claim 1, wherein the range is 5 or less and 0.1 or more.