JPH08305051A - Image carrier, process cartridge and image forming device - Google Patents

Abstract

PURPOSE: To provide a very long-life image carrier, a process cartridge and an image forming device which do not cause a blurring of an output image and whose wear are reduced. CONSTITUTION: The image carrier 1 is constituted so that lubricating grains 3 are contained at least in the upermost surface layer thereof and the containing quantity of the grain 3 is continuously or intermittently increased toward both end parts and provided with an organic photosensitive layer on an electrical conductive supporting body. The process cartridge is provided with the image carrier 1 and set so that it can be loaded and unloaded with respect to the image forming device by integrating a contact type electrostatic charge device electrostatically charging the carrier 1 by making an electrostatic charge member 2 abut on the carrier 1. The image forming device is provided with the contact type electrostatic charge device electrostatically charging the carrier 1 by making the electrostatic charge member 2 abut on the carrier 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies an oscillating voltage to a charging member, brings the charging member into contact with an image carrier to charge the surface of the image carrier, and writes image information to form an image. The present invention relates to an image carrier, a process cartridge, and an image forming apparatus used in the image forming apparatus of the method.

[0002]

2. Description of the Related Art In contact charging, a charging member to which a voltage is applied is brought into contact with an image carrier to transfer the charge to the image carrier, thereby charging the surface of the image carrier to a desired potential.
It has the following advantages over the corona discharge device that has been widely used as a charging device.

A) The voltage required to obtain the desired potential on the surface of the image carrier is low.

B) Since the amount of ozone generated during the charging process is extremely small, the structure of the exhaust system of the apparatus can be simplified.

FIG. 9 shows an embodiment thereof. Reference numeral 1 is an image carrier, and 2 is a charging roller as a charging member. The image carrier 1 is composed of a conductive support 1a and a photosensitive layer 1b. In this embodiment, the image carrier 1 is rotationally driven in one direction at a predetermined peripheral speed. Further, the charging roller is the core bar 2
a and a conductive roller body 2b formed on the outer periphery thereof. This roller is pressed against the image carrier at a predetermined pressure by the action force of the push springs 20 acting on both ends thereof, and is driven / rotated by the rotation of the image carrier.

Reference numeral 21 denotes a power source for applying a voltage to the charging roller 2, and the power source 21 supplies the core metal rod 2 of the charging roller 2.
Image carrier 1 in which a voltage is applied to the charging roller through a contact leaf spring (not shown) brought into contact with a, and is rotated and driven.
The outer peripheral surface of is uniformly charged. The above is the specific configuration of contact charging.

[0007]

Although the contact charging has the above-mentioned advantages, wear on the surface of the image carrier and the charging member, which is a disadvantage due to the contact structure, is recognized. In particular, the surface of the image carrier is also affected by the cleaning blade 10 (FIG. 9) that is brought into contact with the surface of the image carrier, and the degree of wear is greater than that of other components. This is because when the discharge is repeated, the surface layer of the image carrier gradually deteriorates, and the cleaning blade rubs against the surface layer to cause scraping. As the surface wear of this image carrier progresses,
This causes a decrease in sensitivity of the image carrier.

The surface potential V ₀ of the image carrier given by the charger and the film thickness d of the photosensitive layer of the image carrier have the following relationship.

[0009] Here, Q is the amount of charge per unit area given to the image carrier, C is the capacitance per unit area of the photosensitive layer, ε ₀ is the dielectric constant in vacuum, and ε _r is the relative dielectric constant of the photosensitive layer. . Therefore, as can be read from the equation (1), when the film thickness d of the photosensitive layer decreases, a larger amount of electric charge Q is required to apply a constant surface potential V ₀ to the image carrier. That is, since the electric charge Q required to secure the same surface potential V ₀ increases, the potential of the exposed portion does not sufficiently drop under the image forming conditions before the abrasion of the photosensitive layer. If this phenomenon occurs in the image carrier, for example, on the image output paper surface of the reversal development, the density of the portion that should be black should be printed low, which causes a problem that the print quality is significantly deteriorated. For example, an OPC (organic photoreceptor) image carrier often used in electrophotography has a CTL layer, which is a charge transport layer, on the outer periphery of a charge generation layer called a CGL layer.
It has been confirmed that such image roughness becomes remarkable when the thickness is less than or equal to μm.

Further, another problem caused by the decrease in film thickness is a decrease in withstand voltage on the surface of the image carrier during charging. When the withstand voltage of the surface layer of the image carrier decreases, current leakage occurs, the charging voltage on the surface of the image carrier decreases, and a black streak image appears in the output image. The leak generated on the surface of the image bearing member affects the output image because the voltage drop spreads over the entire area of the image bearing member even if the location where the leak occurs is in the non-image area. The image carrier in such a state has to be replaced and discarded. This is not desirable from a cost or environmental standpoint.

Further, as a result of the research conducted by the present inventors, in the case where the charging roller is brought into contact with the image carrier to carry out charging, wear is particularly severe at the longitudinal end of the image carrier as compared with the central part of the image carrier. I found that there was a problem.

First of all, the charging roller used for contact charging is usually provided with a surface layer consisting of a high resistance layer on the roller base body as a countermeasure against leakage at the pinhole portion of the image carrier. These surface layers are usually provided by coating the roller base with a coating liquid from the viewpoint of cost and the like. However, when coating a roller-shaped substrate, it is difficult to uniformly control the coating film thickness within a range of about 10 mm from the roller end due to the liquid dripping at the end or the wraparound of the liquid. Is. For this reason, when the film thickness of the high resistance layer for preventing leakage is large, the current concentrates on the part where the film thickness is relatively small, and the discharge deterioration of the surface of the image carrier progresses.

As shown in FIG. 2, the end portion of the charging roller 2 may be swollen and deformed, and this portion and the image carrier 1 cause a discharge during charging in a minute space formed at the end portion. Occurs in comparison with other areas. The surface of the image bearing member in the area where these phenomena occur is more likely to deteriorate than in other areas, and even if this portion is rubbed in the same manner as other portions, the amount of abrasion is greater. Becomes Further, as described above, the charging roller 2 has a structure in which both ends of the charging roller 2 are pressed by the pressing springs 20 to be brought into pressure contact with the image carrier 1. In addition, 4 is a flange. As a result, the charging roller bends in the longitudinal direction, and the pressure contact force at the end portion becomes larger than at the center portion, and the abrasion due to mechanical force easily occurs. Further, in general, the thickness of the photosensitive layer at the edge of the image bearing member is more uneven than that at the center, and the thickness of the portion where the photosensitive layer rises at the edge is thin, which is one factor that promotes edge scraping. Become. Further, the end portion of the charging roller often comes into contact with the rising portion of the photosensitive layer of the image carrier. In recent years, as the downsizing of image forming apparatuses used for personal small printers and the like has progressed, the longitudinal dimensions of the image carrier and the charging roller must be designed to be as short as the image forming width (image area). Is. Due to these factors overlapping, wear at the end of the image carrier progresses significantly. Further, if the abrasion continues as it is, the withstand voltage is lowered at the edge portion of the image bearing member where the abrasion speed is fast, and the current is concentrated in that portion, so that the image cannot be uniformly charged over the entire length of the image bearing member and fog occurs.

At present, in order to reduce the abrasion of the surface of the image bearing member, a method of adding particles having lubricity to the material of the surface layer of the image bearing member and uniformly dispersing the particles over the entire surface of the image bearing member is known. It is used. Lubricating particles added / dispersed to the surface layer of the image bearing member act to reduce the frictional resistance with those in contact therewith, and have the effect of reducing the amount of abrasion.

However, it was confirmed in the course of study of the present invention that the output image is blurred when the lubricating particles are excessively added according to the scraped amount.

In the case of a commonly used electrophotographic image bearing member, the photosensitive layer or its protective layer is located at the outermost layer.
Therefore, when the lubricating particles are added, they are dispersed in this photosensitive layer or its protective layer. At this time, since the lubricating particles reflect and scatter the light irradiated on the surface of the image carrier for drawing the latent image, image blur occurs. This means that the quality of the output image must be sacrificed to some extent in order to improve the wear resistance of the conventional image carrier by uniformly dispersing the lubricating particles on the surface layer. . Based on these two conflicting problems, the purpose of the present invention was set as follows.

The object of claim 1 according to the present application is to suppress the blurring of the output image which occurs when the lubricating particles are uniformly contained in the entire outermost layer of the image bearing member, and to remarkably occur at the end portion of the image bearing member. The purpose is to effectively reduce the abrasion that occurs and extend the life of the image bearing member.

An object of claim 2 of the present application is to improve the durability of a process cartridge having a contact charging device by using the image carrier of claim 1.

An object of claim 3 of the present application is to extend the image carrier exchange cycle of an image forming apparatus having a contact charging device using the image carrier of claim 1.

The object of claim 4 of the present application is to effectively reduce the abrasion significantly generated at the edge of the image carrier having the organic photosensitive layer on the conductive support, and to affect the image quality. The purpose is to extend the life of the image carrier.

It is an object of claim 5 of the present application to improve the durability of a process cartridge having a contact charging device by using the image carrier of claim 4.

An object of claim 6 of the present application is to extend the image carrier exchange cycle of an image forming apparatus having a contact charging device by using the image carrier of claim 4.

An object of claim 7 of the present application is to manage the amount of lubricating particles contained in the image area and the non-image area separately for each of the areas so that the image quality and the durability are compatible with each other.

[0024]

The present invention is characterized by the following configurations.

(1) An image carrier characterized in that at least the outermost layer contains lubricating particles, and the content of the lubricating particles increases continuously or intermittently toward both ends.

(2) An image carrier according to claim 1, which is integrated with a contact charging device for charging by charging a charging member to the image carrier so as to be detachable from the image forming apparatus. Characteristic process cartridge.

(3) An image forming apparatus comprising the image carrier according to claim 1 and a contact charging device for charging by charging a charging member to the image carrier.

(4) The image carrier according to claim 1, further comprising an organic photosensitive layer on the conductive support.

(5) An image carrier according to claim 4, which is integrated with a contact charging device for charging by charging a charging member to the image carrier so as to be detachable from the image forming apparatus. 6
Process cartridge to collect.

(6) An image forming apparatus comprising the image carrier according to claim 4 and a contact charging device for charging by charging a charging member to the image carrier.

(7) The image carrier according to claim 1 or 4, wherein the content of the lubricating particles is different between the image area and the non-image area.

The means and actions relating to each claim are as follows.

According to the first aspect of the present invention, the lubricating particles are contained in at least the material of the outermost layer of the image bearing member, and the amount thereof is increased at the edge of the image bearing member where the wear is particularly remarkable. Acts to reduce the frictional resistance with a cleaning blade or the like that scrapes the surface layer of the image bearing member.
Further, suppressing the content of the lubricating particles in the central portion of the image bearing body with less wear is used to reduce the reflection / scattering of the scanning light by the particles and avoid blurring of the output image.

According to a second aspect of the present invention, means for mounting the image bearing member of the first aspect on a process cartridge having a contact charging device is adopted, which acts to prolong the life of the process cartridge. The process cartridge mentioned here includes at least a charging member and the image carrier according to claim 1.
A cartridge container that integrally houses the charging member and the image bearing member is provided, and can be freely attached to and detached from the apparatus body of the image forming apparatus.

According to a third aspect of the present invention, means for mounting the image bearing member of the first aspect on an image forming apparatus having a contact charging device is provided, and acts to reduce the trouble of maintenance. The image forming apparatus includes a charging member, the image carrier according to claim 1, an exposing unit that exposes the image carrier to form an electrostatic latent image, and a toner is attached to the electrostatic latent image to form a visible image. The developing device may be provided with a transfer device that transfers the visible image onto a transfer material.

According to a fourth aspect of the present invention, the material of the outermost surface of the image carrier having an organic photosensitive layer on a conductive support contains lubricating particles, and the amount of the particles is particularly large at the edge of the image carrier. The number of parts in the image area and the number in the image area are reduced.This reduces frictional resistance with a cleaning blade that rubs the surface layer of the image bearing member, and reduces reflection / scattering of scanning light by particles, thereby reducing the output image. It works to avoid blur.

According to a fifth aspect of the present invention, means for mounting the image carrier having the organic photosensitive layer on the conductive support of the fourth aspect in a process cartridge having a contact charging device is adopted. It acts to lengthen.

According to a sixth aspect of the present invention, a means of mounting the image carrier having the organic photosensitive layer on the conductive support of the fourth aspect in an image forming apparatus having a contact charging device, and extending the exchange cycle thereof. It works to reduce the trouble of maintenance.

According to the seventh aspect, means for changing the amount of the lubricating particles to be contained in the image area and the non-image area is adopted. For example, when it is desired to greatly improve the durability, the image quality is reversed. It acts so that the amount of particles required to match the characteristics of each region can be individually selected, such as when priority is given.

[0040]

【Example】

[Embodiment 1] FIG. 1 is a cross-sectional model view of an image bearing member of the present invention, and FIG. 3 is a vertical cross-sectional model diagram of an image bearing member and a contact charging roller.

Reference numeral 1 denotes an image carrier, which is a drum support 1a,
It comprises a photosensitive layer 1b and an undercoat layer 1e. The photosensitive layer 1b further includes a CGL layer 1c which is a charge generation layer and a CTL layer 1 which is a charge transport layer.
d. The image carrier having such a structure is
It is called a PC (organic photoreceptor) image carrier. Further, flanges 4 for attaching to the main body and the cartridge are attached to both ends of the image carrier 1 in the figure. In addition, 3 is a lubricating particle.

The drum support 1a is made of a conductive material such as aluminum, stainless steel, titanium, or chromium. As another special structure, it is possible to use paper or plastic in which conductive particles such as carbon black are impregnated with a binder resin.

The CTL layer 1d is formed by coating an organic photoconductor with a binder resin and applying it. CTL layer 1
The film thickness of d is preferably 5 to 50 μm, and 8 to 30 μm
Is more preferable, and the mass ratio of the charge transport material and the binder resin is preferably 5: 1 to 1: 5.

For the CGL layer 1c, one kind or a mixture of materials such as a diazo pigment, a quinocyanine pigment, an indigo pigment, a quinone pigment, a bisbenzimidazole pigment, a quinacridone pigment, a phthalocyanine pigment, and a perylene pigment may be deposited or may be deposited. It can be formed by dispersion coating with a suitable binder resin. The binder resins listed here can be selected from a wide range of insulating resins or organic photoconductive polymers. As the insulating resin, polyvinyl butyral, polycarbonate, polyester, phenoxy resin, acrylic resin, polyamide, cellulose resin, polyvinyl alcohol and the like can be used, and as the organic photoconductive polymer, polyvinyl anthracene, polyvinyl pyrene and the like can be used. The thickness of the CGL layer 1c is 0.01 to 15
μm is preferable, 0.05 to 5 μm is more preferable,
The mass ratio of the charge generating material to the binder resin is preferably 10: 1 to 1:20.

An undercoat layer 1e having an adhesive and barrier function is provided between the drum support 1a and the CGL layer 1c.
As the material, polyvinyl alcohol, nitrocellulose, polyamide, gelatin, aluminum oxide, casein, etc. are used. In order for the undercoat layer 1e to exhibit its function,
It is preferable that the film thickness is 5 μm or less and the volume resistance is 10 ⁷ Ω · cm or more.

A charging roller 2 as a contact charging member is in contact with the image carrier. The charging roller includes a cored bar 2a made of stainless steel and a conductive rubber 2b. Conductive rubber 2
For b, a synthetic rubber such as chloroprene rubber or styrene butadiene rubber in which conductive powder such as conductive carbon or tin oxide is dispersed to adjust the volume resistivity is used.
Further, a leak prevention layer 2c having a volume resistance value of about 10 ¹⁰ Ωcm is provided on the outer periphery thereof.

In this embodiment, an aluminum cylinder having a diameter of 30 mm and a length of 260 mm was prepared as the drum support 1a, on which 4 parts of copolymerized nylon and 4 parts of type 8 nylon were added, 50 parts of methanol and 50 parts of n-heptanol.
And then dip-coated to form an undercoat layer 1e having a thickness of 0.6 μm.

Next, as the CGL layer 1c, 10 parts of copper phthalocyanine pigment and 10 parts of polyvinyl butyral resin were dispersed together with 120 parts of cyclohexanone in a sand mill for 10 hours, and 30 parts of methyl ethyl ketone was added to the dispersion to form the undercoat layer 1e. The coating was applied to the top to a thickness of 0.15 μm.

Further, 10 parts of a polycarbonate resin having a mass average molecular weight of 120,000 was dissolved in 80 parts of monochlorobenzene together with 10 parts of a hydrazone compound, and further, PTFE resin particles having a diameter of 0.3 μm were used as the lubricating particles in a weight ratio of 2 to the polycarbonate resin. Mix and disperse at 0.5%, and CG
16 μm by spraying on L layer 1c
The CTL layer 1d was formed with a thickness of. At this time, portions other than the portion where the latent image is formed were masked, and the charge transport layer having the above composition was formed only in the image area.

Next, the surface of the image area of this image bearing member is masked, and the material of the charge transport layer mentioned above is used for the PTFE.
C that is obtained by changing only the distribution of resin particles to a mass ratio of 10%
Spray coating was performed on the GL layer 1c.

With the above procedure, PTFE is added to the photosensitive layer material.
An image bearing member was produced in which the resin particle content was divided into 2.5% in the image area and 10% in the non-image area on both ends.

The coating width of the photosensitive layer of the image bearing member is 250 mm.
Then, the image area was set from the center to 210 mm. This image carrier has a non-image area of 20 mm on both ends, and the end portion of the charging roller is in pressure contact with this portion.

The core bar 2a of the charging roller 2 has a diameter of 6 m.
m, 256 mm long stainless steel round bar, conductive rubber 2b
Length 230 cm, volume resistance 10 ³ Ωcm, film thickness 2.
8 mm carbon-dispersed styrene-butadiene rubber was adopted for each.

Further, the volume resistance is 10 ⁹ to ¹⁰ 10 around the outer circumference.
Ωcm epichlorohydrin rubber was applied with an average film thickness of 150 μm to form the leak prevention layer 2c.

The details of the apparatus used to measure the degree of wear on the surface of the image bearing member will be described below.

[0056] Process speed 50 mm / sec, a latent image potential dark portion potential = -650 V light potential = -150 V-1 primary bias 500 Hz, 1800 V superimposing and developing conditions a DC voltage of -670V to the AC voltage _pp 1800 Hz, 1600 V _pp Superimposing a DC voltage of -500 V on the AC voltage of the above, the wear amount of each part of the surface layer of the image carrier was measured when 1000 sheets were passed under the above conditions, and the image carrier having the configuration of the present example was measured. In the body, it was reduced to about 70% compared to the case where no PTFE resin particles were added. When the number of sheets to be passed is further increased and the difference between the image on the printing paper surface and the image carrier without addition of PTFE resin particles having the same film thickness is compared, it is found that about 600
Regular fog occurred in 0 sheets, whereas the phenomenon could be confirmed in the product containing the PTFE resin particles after 10,000 sheets.

At the same time, the ratio of the PTFE resin particles added to the CTL layer of the image bearing member was changed uniformly over the entire area of the image bearing member by the same material and manufacturing method, and the characteristics were evaluated. Table 1 shows the contact portion of the charging roller at the central portion and the end portion of the surface layer of the image carrier when 1000 sheets were passed by changing the mixing amount of the PTFE resin particles of the image carrier from 0% to 15% by mass ratio. It is a summary of the amount of wear and the change in the image.
Further, FIG. 4 shows a graph in which the horizontal axis represents the amount of lubricating particles added and the vertical axis represents the amount of wear, and the change thereof.

[0058] (Unit: μm) ○ = No blur △ = No problem in practical use × = Blurred, unusable

As can be seen from Table 1 and FIG. 4, the amount of wear on the surface of the image bearing member was greatly reduced as compared with the case where the PTFE resin particles were not added. This is because the PTFE resin particles acted to reduce the friction between the surface of the image bearing member and the cleaning blade or the like rubbing the surface of the image bearing member. Further, the effect can be recognized when the addition amount of the lubricating particles is 1%.

However, the content of PTFE resin particles is 10%.
If it exceeds the range, the visible image on the printed paper is blurred. This is a phenomenon that occurs because the laser light that scans the surface of the image carrier collides with and scatters on the lubricating particles dispersed in the photosensitive layer. However, it can be said that there is no problem in practical use when the addition amount of image blur is 10% or less. However, the amount of wear does not decrease significantly when the amount of lubricating particles exceeds 7.5%. Therefore, it is optimum to add the lubricating particles within the range shown by the shaded portion in FIG. 4 to obtain the effect of the invention. Therefore, in the present embodiment, the amount of particles added in the central portion is 1% or more and 7.5% or less, and the amount added in the end portion is larger than that in the central portion. It prevents the image carrier from reaching the end of its life from the most worn parts.
The life of the entire image carrier is extended.

Further, the addition amount of the lubricating particles does not necessarily have to be divided into the image area and the non-image area. For example, since the frequency of printing / drawing up to the very limit of the image area width at the time of actual image output is relatively low, the amount of lubricating particles may be increased also at the edge of the image area. If this method is applied, it is possible to further reduce the size of the image carrier and the charging roller in the longitudinal direction.

In this embodiment, PTFE particles were used as the lubricating particles, but the same effect can be obtained if the material has excellent lubricating properties. For example, PFA, FEP, PVDF, CTF
Fluorine-based resins such as E and EFE, silicon-based resins, polyacetals, polyamides, polyimides, ethylene vinyl acetate, acrylic resins, epoxy resins, N-methoxymethylated nylon, etc. can be said to be suitable materials. However, with respect to the particle size, if the particle size is too large, image blurring due to diffused reflection of the irradiation light is likely to occur, so that a particle size of 0.1 to 10 μm, preferably 0.1 to 1 μm is preferably used.

[Embodiment 2] FIG. 5 is a sectional view of an image bearing member provided with a protective layer (hereinafter referred to as an OCL layer) according to a second embodiment of the present invention and a charging roller.

Reference numeral 5 denotes an image carrier, which is a drum support 5a,
The photosensitive layer 5b, the undercoat layer 5e, and the OCL layer 5f. The photosensitive layer 5b is further formed of a CGL layer 5c which is a charge generation layer and a CTL layer 5d which is a charge transport layer. The most significant feature of this embodiment is that the above-mentioned OCL layer 5f for protecting the photosensitive layer 5b is present so as to surround the photosensitive layer 5b. The OCL layer 5f is made by mixing and dispersing conductive powder in a photocurable acrylic resin. Photocurable acrylic resin is a non-conductive material,
When the image carrier is covered as it is, the electric charges applied during charging cannot pass through the OCL layer. Therefore, by adding a conductive powder as appropriate, it becomes possible to provide conductivity suitable for the process conditions. Further, in contrast to the case where the lubricating particles were added to the photosensitive layer in Example 1, in the image carrier of this example, the lubricating particles are mixed and dispersed in the OCL layer 5f.

In this embodiment, the diameter of the drum supporting member is 3
0mm, 260mm long aluminum cylinder,
Undercoat layers 5e and C were formed with the same method and film thickness as in Example 1.
The GL layer 5c and the CTL layer 5d were formed.

Next, a particle size of 0.0 is added to the photocurable acrylic resin.
An OCL solution is prepared by dispersing 5 μm of tin oxide powder and further mixing 25% by weight of acrylic resin as silicone resin fine particles having a particle size of 0.3 μm as lubricating resin particles.
At this time, the dispersion amount of the tin oxide powder is 1 when the resistance of the OCL solution is 1.
Adjust so that it is in the range of 0 ¹⁰ to 10 ¹⁵ Ω. This is spray-painted on the CTL layer 5d with the non-image area masked to form the OCL layer 5f only in the image area.

Subsequently, an OCL solution was prepared in which the proportion of the silicone resin fine particles to be mixed with the photo-curable acrylic resin was changed to 50% by mass ratio, and the non-image area was spray-coated to form an OCL layer 5f having a thickness of 3 μm. To form.

By the procedure described above, an image bearing member was produced in which the content of the silicone resin fine particles was divided into 25% in the image area and 50% in the non-image area on both ends with respect to the photocurable acrylic resin.

Details of the apparatus used for measuring the degree of wear of the surface of the image bearing member will be described below. However, the charging roller used in Example 1 was used. Similarly, the coating width of the photosensitive layer of the image bearing member was also set to 250 mm, and the image area was set to 210 mm, which is distributed from the center. This image carrier has a non-image area of 20 mm on both ends, and the end portion of the charging roller is in pressure contact with this portion.

[0070] Process speed 50 mm / sec, a latent image potential dark portion potential = -650 V light potential = -150 V-1 primary bias 500 Hz, 1800 V superimposing and developing conditions a DC voltage of -670V to the AC voltage _pp 1800 Hz, 1600 V _pp Superimposing a DC voltage of -500V on the AC voltage of the above, using the experimental apparatus described above, the difference between the image on the printing paper surface and the image carrier without addition of silicone resin particles having the same film thickness was compared. Regular fogging occurred in about 8,000 sheets of the product, whereas the phenomenon could be confirmed in the product containing the silicone resin fine particles after 12,000 sheets. From these results, it can be seen that the silicone resin fine particles added to the OCL layer reduced the frictional resistance with the scraped material on the surface of the image bearing member and improved the durability.

At the same time, the content of the silicone resin fine particles in the image bearing member is varied over the entire range of 0 to 60%, and the same apparatus is used to set
Table 2 shows the relationship between the amount of abrasion of the central portion of the image holding member and the contact portion of the end charging roller and the image blur when 0 sheets were intermittently durable for two sheets for 40 seconds. Further, FIG. 6 shows a graph in which the horizontal axis represents the amount of lubricating particles added and the vertical axis represents the amount of wear, and the change thereof.

[0072] (Unit: μm) ○ = No blur △ = No problem in practical use × = Blurred, unusable

As can be seen from Table 2 and FIG. 6, the abrasion amount of the image bearing member starts to decrease from the content of the silicone resin fine particles below 1%, and when it exceeds 50%, the decreasing rate becomes smaller.

Further, in this embodiment, since the lubricating particles are dispersed in the OCL layer which is thinner than the CTL layer in the first embodiment, the probability that the laser beam scanned on the surface of the image carrier collides and scatters, and the image is reduced. Blurring is less likely to occur. Therefore, CTL
More lubricating particles can be added as compared with the case of adding to the layer, but even in this case, image blur occurs when the content exceeds 50%. From the above results, it can be said that it is effective to add the lubricating particles to the image area within the range of the shaded area shown in the graph of FIG. Therefore, in this embodiment, the amount of particles added in the central portion is set to 1% or more and 25% or less, and the amount of addition is larger in the end portions than in the central portion, so that the edge wear can be prevented without affecting the image quality. The life of the image bearing member was prevented from reaching the end of the image bearing member first, and the life of the entire image bearing member was extended.

Further, as the lubricating particles to be added, even if other than the PTFE resin particles used in Example 1, for example, silicone type lubricating particles are used as in this Example, the abrasion speed thereof is slightly changed. Therefore, it is more effective in reducing the amount of wear as compared with the image bearing member containing no lubricating particles.

If the image bearing member is constructed as in this embodiment,
Similar to the case where the PTFE particles are used as the lubricating particles as in Example 1, it has an effect of extending the life of the image carrier while suppressing the influence on the image quality.

[Third Embodiment] FIG. 7 is a cross-sectional view of a process cartridge incorporating the OPC image bearing member 1 of the first embodiment. This process cartridge includes a toner container 6 equipped with a rotary toner carrier 7 and a D blade 8.
And a waste toner container 9 on which an image carrier 1, a charging roller 2, and a cleaning blade 10 are mounted.

The amount of the insulating toner 11 enclosed in the toner container 6 is uniformly adjusted by the rotary toner carrier 7 and the D blade 8, and is conveyed to the surface of the image carrier while being charged.

On the other hand, a latent image is drawn on the image carrier 1 charged by the charging roller 2 while rotating in the direction of the arrow, by the irradiation light from the main body side. Further, a bias current is applied to the toner carrier 7 from the main body, whereby the insulating toner 11 is transferred to the image carrier and the toner carrier 7.
Reciprocate between. At this time, the actual potential on the image carrier 1 is a negative potential in both the bright and dark portions of the latent image, and the insulating toner corresponding to this potential adheres to the surface of the image carrier, so that the latent image is developed. Done.

Further, the image formed on the image carrier is sent to the transfer roller 12 provided on the main body side. When positively charged from the back of the print paper 13, the print paper 1
The surface of 3 is also charged to a positive potential, and if this potential is higher than the potential of the place where the insulating toner 11 is attached, the toner is attracted to the paper and transferred.

The insulating toner 11 remaining on the image carrier 1 during transfer is scraped off by the cleaning blade 10 before being charged again and accumulated in the waste toner container 9.

In order to confirm the effect of the present invention, the image carrier of Example 1 was prepared in which 2.5% by mass of PTFE particles were added to the CTL layer in the central portion and 10% to the CTL layer in the edge non-image area. In addition to the body, an image bearing body was prepared in which 2.5% of PTFE particles were added to the entire CTL layer. As described in the first embodiment, the value of 2.5% takes image blur into consideration. This was replaced with the above-mentioned process cartridge, images were printed under the following conditions, and the number of prints until the background fog occurred was measured.

[0083] Process speed 50 mm / sec, a latent image potential dark portion potential = -650 V light potential = -150 V-1 primary bias 500 Hz, 1800 V superimposing and developing conditions a DC voltage of -670V to the AC voltage _pp 1800 Hz, 1600 V _pp -500V DC voltage is superposed on the AC voltage of the toner-Toner carrier material / dimension Aluminum 250 mm (total length), φ14 mm-C blade material Urethane, t = 1.5 mm As a result, a process using the image carrier of Example 1 In the cartridge, regular fog did not occur until about 11,000 sheets were printed, while 2.5% PTF was applied to the entire area of the image carrier.
When E particles are evenly dispersed, about 8
The phenomenon occurred at 000 sheets.

As described above, if the structure of the cartridge of this embodiment is adopted, the life of the cartridge itself can be extended without deteriorating the image quality.

[Embodiment 4] FIG. 8 shows an image forming apparatus using the OCL image carrier of Embodiment 2.

Similar to the process cartridge of the third embodiment, the amount of the insulating toner 11 is uniformly adjusted by the rotary toner carrier 7 and the D blade 8, and is conveyed to the surface of the image carrier while being charged.

On the other hand, a latent image is drawn on the image carrier 5 charged by the power source (not shown) through the charging roller 2 while rotating in the direction of the arrow, by the irradiation light from the laser irradiation device 16.

A bias current is applied to the toner carrier 7 to reciprocate the insulating toner 11 between the image carrier 5 and the toner carrier 7. At this time, the actual potential on the image carrier 5 is a negative potential in both the bright and dark areas of the latent image, and the insulating toner corresponding to this potential adheres to the surface of the image carrier, and the latent image is not developed. Done.

Further, the image formed on the image carrier is sent to the transfer roller 12. Positive charging is performed from the back surface of the print paper 13 conveyed by the paper feed roller 15 from the paper feed tray 17. The surface of the print paper 13 is also charged to the brass potential, and if this potential is higher than the potential of the place where the insulating toner 11 is attached, the toner is attracted to the paper and transferred.

The insulating toner 11 remaining on the image carrier 5 during transfer is scraped off by the cleaning blade 10 before being charged again, and is accumulated in the waste toner container 19. In addition, 14 is a fixing roller and 18 is a toner container.

In order to confirm the effect of the present invention, the image carrier of Example 2 in which 25% by weight of silicone particles were added to the CTL layer in the central portion and 50% to the CTL layer in the edge non-image area was added. In addition, an image carrier was prepared in which 25% of silicone particles were uniformly added to the entire OCL layer. This was replaced with the above-mentioned image forming apparatus, image printing was performed under the following conditions, and the number of printed sheets until the occurrence of regular fog was measured.

[0092] Process speed 50 mm / sec, a latent image potential dark portion potential = -650 V light potential = -150 V-1 primary bias 500 Hz, 1800 V superimposing and developing conditions a DC voltage of -670V to the AC voltage _pp 1800 Hz, 1600 V _pp -500V DC voltage is superposed on AC voltage of -Toner carrier material / dimension Aluminum 263mm (total length), φ16mm-C blade material Urethane, t = 1.5mm As a result, image using image carrier of Example 2 In the forming apparatus, the normal fog did not occur until about 14,000 sheets were printed, whereas when the one in which 25% of silicone particles were evenly dispersed over the entire area of the image carrier was used, about 10000.
The phenomenon occurred on one sheet. From the above, it was confirmed that the wear amount of the image bearing member is reduced, and thus the effect of extending the replacement period of the image bearing member in the image forming apparatus is extended.

[0093]

As described above, by constructing the image carrier according to the present invention, it is possible to effectively reduce the significant wear of the end portion of the image carrier during contact charging, and as a result, the image carrier is carried out. It can extend the life of the body.

The effects corresponding to each claim will be summarized below.

According to the first invention of the present application, it is possible to reduce the abrasion of the end portion of the image bearing member, which is subject to severe abrasion, without interfering with the image region of the image bearing member which affects the image quality, and to extend the life of the image bearing member. It will be possible to extend it from the present. In addition, this effect can be obtained by including the lubricating particles of the present invention in the outermost surface layer regardless of the type of the image bearing member that is charged by the contact charging device.

According to the second invention of the present application, the durability of the process cartridge having the contact charging device can be improved by using the image carrier according to the first aspect. Further, when the cartridge is recycled, the image carrier having a long life can be reused, which is beneficial for environmental protection and cost.

According to the third invention of the present application, it is possible to extend the image carrier exchange cycle of the image forming apparatus having the contact charging device by using the image carrier of claim 1 and reduce the maintenance labor. You can

According to the fourth invention of the present application, the abrasion of the surface layer of the image bearing member is reduced without affecting the image quality,
The life of the image carrier having the organic photosensitive layer on the conductive support can be extended.

According to the fifth invention of the present application, it is possible to prolong the service life of a process cartridge having an image carrier having an organic photosensitive layer on a conductive support and to recycle it.

According to the sixth invention of the present application, the image carrier exchange cycle of an image forming apparatus having an image carrier having an organic photosensitive layer on a conductive support is extended to reduce maintenance work. can do.

According to the seventh invention of the present application, for example, when it is desired to give priority to a great improvement in durability, or conversely to give priority to image quality, the regions of image and non-image are adapted to the characteristics. As described above, the addition amount / dispersion amount of the lubricating particles can be adjusted. Also, they can be done independently without affecting each other's areas.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an OPC image carrier, which is an embodiment of the present invention.

FIG. 2 is a schematic view showing a minute space formed in an image carrier and a charging roller.

FIG. 3 is a schematic vertical sectional view of an OPC image carrier, which is an embodiment of the present invention.

FIG. 4 shows that the content of PTFE resin fine particles in the image bearing member is 0 in the entire range.
It is a graph which shows the change of the abrasion amount of a central part and an edge part of an image carrier when it changes to -15%.

FIG. 5 is a schematic vertical sectional view of an OPC image carrier, which is an embodiment of the present invention.

FIG. 6 is a graph showing changes in the amount of abrasion of the central portion and the end portion of the image bearing member when the content of the silicone resin fine particles in the image bearing member is varied over the entire range of 0 to 60%.

FIG. 7 is a schematic vertical cross-sectional view of a process cartridge including the image bearing member according to the first exemplary embodiment.

FIG. 8 is a schematic vertical sectional view of an image forming apparatus having an image carrier according to a second exemplary embodiment.

FIG. 9 is a schematic vertical sectional view showing an example of a contact charging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Charging roller 3 Lubricating particles 4 Flange 1c, 5c CGL layer 1d, 5d CTL layer 1e, 5e Undercoat layer 5f OCL layer 10 Cleaning blade

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsutoshi Ando 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (7)

[Claims] 1. An image carrier comprising at least an outermost layer containing lubricating particles, and the content of the lubricating particles continuously or intermittently increases toward both ends. 2. The image carrier according to claim 1, which is integrated with a contact charging device for charging by charging a charging member to the image carrier so as to be attachable to and detachable from the image forming apparatus. And process cartridge. 3. An image forming apparatus comprising the image carrier according to claim 1, and a contact charging device for charging by charging a charging member to the image carrier. 4. The image carrier according to claim 1, further comprising an organic photosensitive layer on the conductive support. 5. The image carrier according to claim 4, further comprising a contact charging device that charges a member by bringing a charging member into contact with the image carrier so as to be detachable from an image forming apparatus. And process cartridge. 6. An image forming apparatus comprising the image carrier according to claim 4, and a contact charging device for charging by charging a charging member to the image carrier. 7. The image carrier according to claim 1, wherein the content of the lubricating particles is different between the image area and the non-image area.