JP2002278262A - Developing device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device and a process cartridge effectively preventing lack of images such as HT (halftone) longitudinal streaks and white spots in images generated in a start stage of use subsequent to toner charging. SOLUTION: The developing device, used for the process cartridge, is provided with an electrophotographic photoreceptor, a contact electrifying member constructed by being supported with bearing members on both end parts and by being pressed and brought into contact with the photoreceptor so as to be driven by and rotate around the photoreceptor, a developer, a developer carrier and a developer controlling member. A lubricant applied to points of contact between the developer carrier and the developer controlling member is composed of spherical polymer particles with >=0.90 average circularity before charging the developer and starting use, in the state of no developer existing yet, and further applied quantity of the lubricant in the longitudinal direction, existing on the developer controlling member and the developer carrier of the developing device, is 0.23-1.40 mg/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for various image forming apparatuses employing an electrophotographic system, such as a copying machine and a laser beam printer, and a process cartridge using the developing device.

[0002]

2. Description of the Related Art First, an image forming apparatus employing a conventional electrophotographic system will be described with reference to FIG. FIG.
As shown in FIG. 1, in a general image forming apparatus, a photoreceptor 101 which is a rotatable latent image carrier, a charging device 102 which is driven to rotate with respect to the photoreceptor and charges the photoreceptor to a predetermined potential, Exposure device 10 for forming electrostatic latent image on photoreceptor
3. Developing device 104 that develops the electrostatic latent image on the photoconductor to make it visible, transfer device 105 that transfers the visible image on the photoconductor to the transfer material, and fixing device that fixes the visible image as a permanent image 10
8, a cleaning device 107 for recovering the developer remaining on the photoreceptor without being completely transferred to the transfer material. In recent years, the photoreceptor 101, the charging device 102, the developing device 104, and the cleaning device 107 are integrally incorporated into a process cartridge detachably mounted on the apparatus main body, thereby eliminating the need for maintenance. An image forming apparatus having excellent usability is provided.

[0003] The charging roller 102 shown in FIG.
The surface of the photosensitive drum 101 is urged by a spring (not shown) or the like, and is rotated by the rotation of the photosensitive drum 101. This charging roller is, for example, as shown in FIG.
It is composed of a metal core 2a made of SUS, a conductive elastic layer 2b coated on the outer peripheral surface of the metal core, and a resistance layer 2c coated on the outer peripheral surface. If necessary, a configuration in which an intermediate layer is provided between the conductive elastic layer and the resistance layer may be adopted (not shown).

[0004] Examples of the forming material used for the conductive elastic layer 2b include elastic materials such as ethylene propylene diene rubber, isoprene rubber, styrene butadiene rubber, nitrile rubber, silicone rubber, urethane rubber and fluoro rubber. A material in which a conductive agent such as conductive carbon black is dispersed is known. Examples of the material used for the resistance layer 2c that covers the outer peripheral surface of the conductive elastic layer 2b include film-forming materials such as polyamide resin, polyurethane resin, and fluorine resin, conductive carbon black, and conductive oxide. A material in which a conductive agent such as tin or conductive titanium oxide is dispersed is known.

Further, Japanese Patent Application Laid-Open No. 11-160958 discloses a structure using a seamless tube made of a conductive thermoplastic elastomer, for example, a resin containing an ethylene-butylene copolymer, particularly, an ethylene-butylene copolymer. In a styrene-ethylene-butylene-olefin copolymer in which one of both ends of the coalesced is a styrene block polymer and the other is an olefin block polymer, for example,
A charging roller having a resistance layer made of a mixture of a polyolefin resin such as a polyethylene resin is disclosed. According to the above configuration, the photosensitive drum contamination and electrification caused by the exudation of the softening oil or the plasticizer added for the purpose of adjusting the hardness, which had been a problem when a conventional olefin-based elastomer or styrene-based elastomer material was used, were used. It is possible to prevent problems such as sticking of the member to the photosensitive drum, and problems such as toner adhesion to the surface of the charging roller, which are problems when using a low-hardness urethane elastomer.

When manufacturing the image forming apparatus shown in FIG. 7, at least a developer 104c (hereinafter, referred to as toner) and a developer carrier 104a for carrying and transporting the toner are provided.
(Hereinafter referred to as a developing sleeve) and a toner layer thickness regulating member 104 for regulating the toner coating on the developing sleeve.
b (hereinafter, referred to as a developing blade) during the assembly process of the developing device constituted by a developing blade 104b for the purpose of quality check such as appearance inspection.
4c, the developing sleeve 104 is not coated.
It is common practice to rotate a for a certain period of time.

However, at this time, if the developing blade 104b or the developing sleeve 104a is rubbed or scratched, or the developing blade 104b is made of an elastic material such as urethane rubber, the developing blade 104b and the developing sleeve 104a may The frictional resistance causes the developing blade 104
b may turn up in the rotation direction of the developing sleeve 104a. When such a product is put on the market and actually used with the toner 104c, there is a case where a uniform and good toner coating is not formed on the developing sleeve 104a.

[0008] To solve this problem, in the assembly process,
When the developing sleeve 104a is rotated for a certain period of time without being coated with the toner 104c, a lubricant is applied to the surface of the developing blade 104b on the side that comes into contact with the developing sleeve 104a. The lubricant used at this time is coated with the toner 104c on the developing sleeve 104a, and is related to the developing characteristics at the initial stage when the developing device actually starts to be used and the occurrence of development streaks. And those having shapes and the like are selected and used. For example, Japanese Patent Application Laid-Open No. H08-211728 proposes a method in which spherical silicone resin particles having an average particle size of 5 to 30 μm are applied as a powder on a developing sleeve, and Japanese Patent Application Laid-Open No. H11-119551 discloses a method. ~ 45
μm resin particles with an appropriate charge amount (spherical PMM
A, urethane, acrylic, polystyrene, PVDF),
Alternatively, a method of applying amorphous silicone resin particles has been proposed.

[0009]

However, even when the above-mentioned lubricant is used, the following problems may occur. As described above, in recent years, the developing device assembled as described above has
Further, it is provided as a process cartridge which is integrally incorporated with the electrophotographic photosensitive member, the contact charging member (charging roller) and the cleaning device, and is detachably attached to the image forming apparatus main body. And have been used. In such a process cartridge, as shown in FIG. 7, the charging roller 102 is provided so as to be pressed against the photosensitive member 101 and is driven to rotate with respect to the photosensitive member.
The lubricant applied to the charging roller 102 (or the developing sleeve 104a) may be vibrated or suddenly dropped.
Large amounts may adhere to the surface. Then, even if the above-described lubricant is used, the charging roller 102 may not follow (slip) with respect to the photoconductor 101 in some cases.

According to the study of the present inventors, the charging roller 1
02 slips, the sound (charging sound) generated at the time of charging increases, or the photosensitive member 101 and the charging roller 10
It has been found that the surface of the charging roller 102 may be scratched due to a peripheral speed difference from 2, and a vertical streak-like charging failure (hereinafter referred to as “HT vertical streak”) may occur in the halftone image.
This phenomenon occurs because, for example, the charging roller 102 having the outermost layer (resistive layer) made of a resin obtained by mixing an ethylene-butylene copolymer with a polyethylene resin as described above and the lubricating particles having a large particle size, for example, It was found that the effect was more remarkable when spherical silicone resin particles having a particle diameter of 65 μm were used in combination. This is because the resin containing the ethylene-butylene copolymer and the polyethylene resin is relatively brittle and easily damaged, and the scratches generated on the surface of the charging roller use lubricating particles having a large particle diameter. This is considered to be due to the fact that the toner particles naturally become large, and uniform and favorable charging is hindered.

Further, as another problem, when the above-mentioned lubricant remains on the photosensitive drum 101, exposure of the photosensitive member 101 by the exposure device 103 is interrupted, and an electrostatic latent image cannot be formed. Therefore, this may cause image loss (hereinafter, referred to as “image white spots”). Further, the charging roller 1
When the above-described lubricant adheres to the surface of the photoconductor 101 in the form of agglomerates, when the lubricant comes to the nip portion with the photoconductor 101,
If a small amount is discharged onto the photoreceptor, white spots on the image may not easily disappear from the beginning of use.

Accordingly, an object of the present invention is to effectively prevent image loss such as HT vertical stripes and image white spots, which may occur in the initial stage of actually using a new image forming apparatus with toner. An object of the present invention is to provide a developing device and a process cartridge using the developing device.

[0013]

The above objects are achieved by the present invention described below. That is, the present invention, at least, an electrophotographic photoreceptor, a contact charging member that is configured to be held by bearing members at both ends and configured to be brought into pressure contact with the photoreceptor and driven to rotate with respect to the photoreceptor, A developing device used in a process cartridge having a developer, a developer carrier, and a developing device provided with a developer regulating member therein, wherein the developer is charged before the developer is put in and used. A lubricant is applied to a contact portion between the developer carrier and the developer regulating member in a state where the lubricant is not present, and the lubricant is spherical polymer particles having an average circularity of 0.90 or more, and A developing device, wherein the amount of the lubricant applied in the longitudinal direction existing on the developer regulating member and the developer carrying member of the developing device is 0.23 to 1.40 mg / cm; Use the device Russia is Seth cartridge.

[0014]

Next, the present invention will be described in detail with reference to preferred embodiments of the present invention. The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art, and as a result, during the assembly process of the developing device, the developing sleeve is rotated for a certain time in a state where the toner is not coated, and quality check such as appearance inspection is performed. As the lubricant used in the case of performing, a spherical polymer particles having an average circularity of 0.90 or more are used, and the developer regulating member of the developing device and the longitudinal direction present on the developer carrier are present on the developer carrying member. Reduce the amount of lubricant applied to 0.
When the density is 23 to 1.40 mg / cm, it is possible to obtain a developing device in which the above-described image loss such as HT vertical stripes and image white spots, which is generated at an initial stage of starting use of a new image forming apparatus, is effectively prevented. The knowledge has led to the present invention.

The developing device of the present invention is used in a process cartridge detachable from an image forming apparatus. The process cartridge comprises an electrophotographic photosensitive member held at least rotatably, The image forming apparatus comprises a contact charging member which rotates in contact with the photoreceptor by being pressed against the body, and a developing device in which a developer, a developer carrier and a developer regulating member are provided. The above-described developing device of the present invention is configured such that the developer is not present at the contact portion between the developer carrying member and the developer regulating member of the developing device before the toner is actually used. The lubricant is applied to the contact portion between the developer carrier and the developer regulating member. The lubricant used at that time is spherical polymer particles having an average circularity of 0.90 or more. The amount of the lubricant to be applied is 0.23 to 1 in the longitudinal direction existing on the developer regulating member and the developer carrier of the developing device.
It is characterized by being 40 mg / cm.

In the present invention, approximately spherical polymer particles having an average circularity of 0.90 or more are used as a lubricant.
It is preferable to use a spherical polymer particle having a weight average particle diameter larger than the surface roughness Rz of the developing sleeve, for example, 10 to 30 μm, which is used as a lubricant.
Examples of the spherical polymer particles used in the present invention include silicone resin particles, PMMA (polymethyl methacrylate) particles, urethane-based elastic particles, acrylic resin particles, cross-linked polystyrene particles, and PVDF (polyvinylidene fluoride) resin. It is preferably at least one selected from particles.

[0017]

The present invention will be described below in detail with reference to examples. <Embodiment 1> FIG. 1 is a schematic sectional view of an image forming apparatus using a process cartridge of this embodiment. The image forming apparatus includes a process cartridge 9 in which respective process devices such as a photoreceptor 1, a charging roller 2, a developing device 4, and a cleaning device 7 are incorporated, and a transfer roller 5, a fixing device 8, and an exposure device. A device 3 is provided.

Hereinafter, an image forming process by the image forming apparatus will be described. The photoreceptor 1 as a latent image carrier is formed by laminating a photoconductive photosensitive layer on the surface of a conductive substrate made of aluminum.
It is rotationally driven by a driving means (not shown) at a speed of about sec. During the rotation process, the photoreceptor 1 is first subjected to uniform charging of negative polarity by the charging roller 2.
Next, a laser beam corresponding to a time-series electric digital image signal of image information sent from a video controller (not shown) is output by the exposure device 3, and the uniformly charged photosensitive member surface is scanned and exposed at a resolution of 600 dpi. Thereby, an electrostatic latent image is formed.

The electrostatic latent image formed on the surface of the photoreceptor 1 as described above has toner 4c in the developing device 4 carried on a developing sleeve 4a, which is a toner carrier, and further in an image area. By being conveyed, the image is reverse developed and visualized. Thereafter, the toner image is transferred onto the transfer paper P by the action of the transfer roller 5. The transfer paper P to which the toner image has been transferred is separated from the photoreceptor 1 and introduced into the fixing device 8, where the toner image is fixed, and then discharged from the image forming apparatus main body. On the other hand, the transfer residual toner remaining on the photoconductor after the transfer of the toner image is removed by the cleaning device 7, and the next image forming process is performed.

FIG. 3 shows the charging roller. As shown in FIG. 3, the charging roller 2 used in this embodiment has a conductive core 2a and an outer peripheral surface of the core 2a. A conductive elastic layer 2b and a resistance layer 2c coated on the outer peripheral surface thereof
And has an outer diameter of about 12
[Mm]. SU with an outer diameter of 6.0 mm is attached to the cored bar 2a.
A cylindrical product made of S was used.

The conductive elastic layer 2b is formed of an elastic material such as ethylene propylene diene rubber, isoprene rubber, styrene butadiene rubber, nitrile rubber, silicone rubber, urethane rubber, or fluoro rubber, and is made of conductive carbon black or the like. This is a layer in which the volume resistivity is adjusted by dispersing an agent. In this embodiment, the conductive elastic layer 2
As b, a conductive carbon black dispersed in 5 parts by mass of 100 parts by mass of ethylene propylene diene rubber and adjusted to a volume resistivity of 1 × 10 ⁵ Ω · cm or less was used.

The resistance layer 2c coated on the outer peripheral surface of the conductive elastic layer 2b is made of, for example, a resin material such as polyamide resin, polyurethane resin, fluorine resin, or the like, made of conductive carbon black, conductive tin oxide, conductive A material in which a conductive agent such as titanium oxide is dispersed is known. In this example, one of the two terminals of the ethylene-butylene copolymer is a styrene block polymer, and the other is an olefin block polymer, a styrene-ethylene-butylene-olefin copolymer 100 [parts by mass], and a polyethylene resin 30 [ Parts by mass) is mixed with a conductive carbon black 15
A seamless tube in which [parts by mass] were dispersed was used. The volume resistivity of the resistance layer 2c is 1 × 1
0 ⁹ [Ω · cm] and the film thickness is about 300 [μ
m]. If necessary, the conductive elastic layer 2
An intermediate layer may be provided between b and the resistance layer 2c.

The above-mentioned charging roller 2 used in this embodiment
Is obtained, for example, by the following production method. First,
On the outer peripheral surface of the cored bar 2a, a layer of an unvulcanized, unfoamed elastic body (rubber) material in which a compounding agent such as a foaming agent or a conductive agent is uniformly dispersed is formed, and this is set in a molding die. Then, an unvulcanized or unfoamed rubber material layer is vulcanized and foamed by heating to form a conductive elastic layer 2b having a predetermined outer diameter. Further, together with this, a kneaded product made of a resin, a conductive agent, or the like, which has been pelletized in advance, is formed into a tube by an extruder equipped with a predetermined tube forming die, and this is coated on the conductive elastic layer 2b. Thereby, the resistance layer 2c is formed.

In this embodiment, as shown in FIG. 4, the charging roller 2 having the above-described structure is urged in the direction of the photosensitive drum 1 by a spring at both ends of the conductive core via a bearing 21. . As a result, the charging roller 2 becomes the photosensitive drum 1
, And can be driven to rotate as the photosensitive drum 1 rotates. The metal core is electrically connected to a charging bias supply power supply 13 capable of superimposing a DC electric field and an AC electric field. By applying a bias to the charging roller 2 via the metal core, the surface of the photoconductor 1 is brought to a predetermined potential. It is possible to perform a charging process.

As shown in FIG. 1, the developing device 4 generally controls a developing sleeve 4a that carries and conveys the toner 4c in the direction of the photoconductor 1, and a thick toner layer on the developing sleeve 4a. Developing blade 4 as a toner thick layer regulating member
b, and further includes a toner storage chamber for storing toner.

The developing sleeve 4a has a structure in which a coating liquid in which a conductive agent such as carbon is dispersed is coated on a hollow cylindrical tube made of a metal such as aluminum and stainless steel, and the inside thereof is formed by a magnetic force. A magnet roller (not shown) is fixedly arranged to carry the toner. In the present embodiment, a hollow cylindrical tube having a diameter of 16.0 mm made of aluminum was used. The developing sleeve 4a having such a configuration is opposed to the photoreceptor 1 at a predetermined interval, is rotatably supported by a bearing (not shown), rotates in a direction indicated by an arrow, and passes through an electrode (not shown). It is connected to the developing bias power supply.

In this embodiment, as the developing blade 4b,
A thickness t = 1.0 m made of urethane rubber contacted in the counter direction with respect to the rotation direction of the developing sleeve 4a.
m. The toner is supplied to the developing blade 4b.
An appropriate charge is given by the frictional charging with. Normally, the contact pressure of the developing blade 4b is 2 as a linear pressure in the longitudinal direction.
It is about 0 to 50 g / cm.

The developing blade 4b is coated with spherical polymer particles as a lubricant by a method described below at least at a position where the developing blade 4b is not coated with toner at the stage of assembling the developing device, at a position where the developing blade 4b is in contact with the developing sleeve 4a. Have been. The position where the lubricant is applied is not limited to the above, and may be a position where at least the developing blade 4b of the developing sleeve 4a abuts.

Hereinafter, a method of applying the lubricant will be described. A lubricant was applied to a part of the surface of the developing blade 4b as shown in FIG. First, a lubricant (spherical polymer particles) is added to a volatile solvent by adding (lubricant): (PF506).
0): (IPE) = dispersed at a mass ratio of 2.5: 4: 11.
Mix. Here, PF5060 is Fluorinert, and IPE is isopropyl ether. Next, FIG.
As shown in the above, the lubricant-containing solution 10 in the container prepared as described above is applied to an applicator 11
Suction is performed by the nozzle 12 of FIG. With the developing blade 4b fixed and arranged, the nozzle 12 is moved to the coating start position.
The application is performed by moving the solution 10 from the position to the application end position while discharging the solution 10 from the nozzle 12 (10 ′ in the figure is an application portion). The above ratio of the solution containing the spherical polymer particles is an example, and the amount of the lubricant to be applied can be appropriately adjusted by changing the concentration of the polymer particles in the mixed solution.

Here, the definition of the shape (spherical or amorphous) of the polymer particles and the average particle diameter in the present specification will be described. <Shape> In the present specification, the circularity of the polymer particles is 0.9.
Particles of 0 or more were defined as spherical particles, and those of less than 0.90 were defined as amorphous particles. The degree of circularity is an index indicating the degree of unevenness of particles. When the particles are perfectly spherical, the degree of circularity is 1.00, and this value decreases when the surface shape becomes complicated. Such circularity is defined using the following equation. (Circularity) = (Circumference having the same projected area as the particle image) /
(Perimeter of particle projection image)

<Weight Average Particle Size> The weight average particle size of the polymer particles is defined as follows. When the total weight of the particles having a circle equivalent diameter in the range of di to di + 1 is fi, weight average particle diameter = Σ (di × fi) / Σfi The above parameters are all flow particles manufactured by Toagosei Medical Electronics Co., Ltd. The value measured using the image analyzer FPIA-1000 was used.

The present inventors investigated the effect of polymer particles used as a lubricant on image defects,
The shape and the particle size of the polymer particles were variously changed, and the slip of the charging roller and the generation level of image white spots were examined. The results are described below. [Experiment 1] Under the following conditions, a lubricant was applied to a developing blade not coated with toner, the developing blade was incorporated into a process cartridge, and a drop test was performed on the process cartridge. Thereafter, 50 sheets of continuous durable images were printed. At that time, it was confirmed whether or not slippage of the charging roller and occurrence of white spots on the image occurred.

<Lubricants Used in the Experiments> As the lubricants, silicone resin particles having the following shapes A to C and weight average particle diameters were used, and these lubricants were used as (lubricants): (P
F5060) :( IPE) = A mixed solution dispersed in a solvent at a ratio of 2.5: 4: 11 was obtained and applied to the surface of the developing blade by the method shown in FIG. At this time, the total amount of application to the developing blade was adjusted to 70 mg, and the amount of application per unit length in the longitudinal direction of the developing blade was 3.24 mg /
cm.

A: spherical silicone resin particles having a maximum particle size of 65 μm and a minimum particle size of 5 μm and a weight average particle size of 15 μm B: spherical silicone resin particles having a maximum particle size of 10 μm and a minimum particle size of 4 μm and a weight average particle size of 7 μm C and D : Amorphous silicone resin particles having a maximum particle size of 60 μm and a minimum particle size of 3 μm and a weight average particle size of 15 μm

<Effect Test by Lubricant Shape> A developing device and a process cartridge using the developing blade were assembled using the developing blades coated with the lubricant as described above. It was packed in a hexahedral box and dropped six times from a height of 100 cm.
At that time, the box was dropped from all six sides of the box, and it was assumed that the lubricant would adhere to the charging roller in anticipation of the vibration or dropping of the process cartridge occurring in the actual distribution stage. Thereafter, each process cartridge was taken out of the box, the process cartridge was mounted on the image forming apparatus having the configuration shown in FIG. 1, and an image was formed using toner. After image formation, the occurrence of scratches on the charging roller was observed. Further, a triangular mylar tape was stuck on a part of the charging roller, and the occurrence of the charging roller slip was confirmed by comparing the triangular mylar tape with the pitch at the time of following. Further, in the initial stage of use when the image formation is started, it is determined whether or not an image white spot is generated by forming a practical image (halftone).
Obtained images were visually checked and judged according to the following criteria.
The image formation was performed under a standard normal temperature and normal humidity environment (25 ° C., relative humidity 50%). Table 1 shows the obtained results. ：: missing level (no missing). Δ: Slight omission / no problem. X: Image white spots occurred.

[0036]

[Table 1]

<Evaluation Results> (Regarding Slip of Charging Roller) From the results of the above tests, it was found that slipping of the charging roller frequently occurs when a large amount of spherical polymer particles adhere to the surface of the charging roller. In addition, when image formation is started using a new process cartridge, the generation of white spots from the initial stage disappears slowly because a large amount of amorphous polymer particles having a low circularity is formed on the surface of the charging roller in large quantities. Aggregation was found to be the cause.

(Regarding the level of occurrence of slip scratches on the charging roller, generation of HT vertical stripes, and generation of white spots on the image)
As a result, it has been found that when a large amount of spherical polymer particles adhere to the charging roller, the charging roller may not follow the photosensitive member. It is considered that this is because when a spherical lubricant having a high lubricating effect adheres to a part of the charging roller, the static friction coefficient of this part rapidly decreases. It was also found that if a lubricant having a large particle diameter was present, the charging roller slipped, the surface of the charging roller was easily damaged, and HT vertical stripes occurred. This is probably because the lubricant having a large particle diameter is embedded in the roller between the charging roller and the photosensitive drum and moves while shaving the surface. On the other hand, when spherical polymer particles having a small particle size were used, it was found that the charging roller could easily slip, but the surface of the charging roller was not easily damaged. Furthermore, the sphericity is 0.90
If the irregular polymer particles are smaller, even if they adhere to the surface of the charging roller, the coefficient of static friction does not drop significantly, so that the charging roller does not slip and follows the photoconductor. I found that I could rotate.

However, on the other hand, amorphous polymer particles
The adhesion to the surface of the charging roller is large, and it tends to aggregate and adhere easily.If a large amount of this wraps around the charging roller, it is necessary to discharge the mass to the photoreceptor considerably from the start of use. Since it takes time, it has been found that it takes a considerable period from the beginning until the occurrence of white spots on the image disappears.

[Experiment 2] The following experiment was conducted to examine the relationship between the amount of lubricant applied and the occurrence of scratches on the charging roller. The lubricant used for the application was the three types of polymer particles A, B and D used in Experiment 1. The amount of the lubricant applied to the blade was adjusted by changing the concentration of the lubricant in the mixed solution. Other experimental contents and experimental conditions were the same as those in Experiment 1. Table 2 shows the obtained results.

[Table 2]

<Effect Test by Lubricant Application Amount> (Slip flaw of charging roller and HT vertical streak) Table 2
As shown in the above, even if the lubricant has a spherical shape and a large particle size, if the amount of application is reduced, specifically, if the amount of application to the blade is set to 1.39 mg / cm or less, the charging is performed. It was found that the occurrence of the roller scratches and the occurrence of the HT vertical stripes can be effectively prevented. Here, the lubricant applied for the purpose of adjusting the apparatus before the start of use, in the initial stage after the start of use, remains on the developing blade surface, remains on the developing sleeve surface, and is transferred onto the drum. Divided into things to be cleaned. Here, the lubricant remaining on the surface of the developing blade or the lubricant remaining on the surface of the developing sleeve, when subjected to a vibration / drop test in the same manner as in Experiment 1, may sneak into the charging roller portion and cause slippage of the charging roller. I understood. On the other hand, if the amount of the applied lubricant is reduced, even if the lubricant has a spherical shape and a large particle diameter, the lubricant does not flow around the charging roller portion, and slip scratches on the charging roller occur. It turned out that it can be suppressed effectively.

(Driving Torque of Developing Sleeve) Regarding the result of the driving torque of the developing sleeve, it is difficult to evaluate the absolute value of the result because of the influence of the contact pressure of the developing blade, the stirring torque, and the like. A new process cartridge was used, and the toner was supplied to the developing sleeve after the toner seal of the toner storage section was cut. The driving torque depends on the amount of the nip portion of the developing blade and the amount of the surface of the developing sleeve. Although the initial torque increases when the coating amount is small, as shown in Table 2,
It has been found that when a spherical lubricant having a large particle size is used as in A, a good driving torque can be obtained even if the amount of the lubricant is small. ：: The increase is less than 0.5 kgcm. Δ: 0.5 to less than 1.0 kgcm. X: 1.0 kgcm or more.

As for the relationship between the shape and size of the lubricant and the initial torque, an amorphous material (a material having a small sphericity) such as D has a large adhesive force to the surface of the sleeve.
It was found that it was difficult to roll at the nip and the lubrication effect was small. For this reason, as shown in Table 2, it was necessary to apply a large amount of the lubricant in order to reduce the initial torque. On the other hand, spherical ones such as A and B have good rolling properties and a large lubricating effect. Further, it was found that when the particle size of the lubricant was sufficiently larger than the uneven shape of the surface of the developing sleeve, the lubricant was not embedded in the sleeve but rolled well in the nip, so that the lubricating effect was high. That is, it is preferable to use a material such as A having a particle size larger than the developing sleeve surface roughness Rz. The developing sleeve surface roughness Rz used in this embodiment is 8 μm. On the other hand, a material such as B having a small particle size with respect to the uneven shape of the sleeve surface is not caught by the unevenness of the sleeve surface and only slips along with the sleeve.

FIG. 2 shows that a small amount of lubricant was applied (0.46 mg).
/ Cm), the relationship between the particle size of the lubricant composed of the spherical polymer particles used and the torque is shown. As a result, it was found that it is preferable to use the polymer particles having a weight average particle diameter larger than the surface roughness Rz of the developing sleeve, for example, 10 to 30 μm.

As a result of the above Experiments 1 and 2, it was found to be substantially spherical with an average circularity of 0.90 or more and a weight average particle diameter larger than the developing sleeve surface roughness Rz, for example, 10 to 30 μm.
Is used as a lubricant when adjusting the apparatus, and the amount of the lubricant in the longitudinal direction existing on the developer regulating member and the developer carrier of the developing apparatus is 0.23 to 1. By applying so as to be 40 mg / cm, when image formation is actually started using toner by using such a process cartridge, slip of the charging roller,
It has been found that the problem of the initial torque can be improved to a level at which there is no practical problem.

<Embodiment 2> A method of applying a lubricant to a developing sleeve with a powder will be described with reference to FIG. In this embodiment, in order to stably apply a small amount of the lubricant, a method of applying the powder to the developing sleeve is adopted. The application of the lubricant to the developing sleeve was performed by applying a lubricant particle to a sponge roller and bringing the lubricant particle into contact with the developing sleeve. As shown in FIG. 6, the lubricant application device includes a sponge roller 16, a developing sleeve 4a, an application container 15, and a lubricant 17. The sponge roller 16 used at this time was a polyurethane foam having an average foamed diameter of about 360 μm. As the lubricant 17, the polymer particles of A used in the examples were used.

On the other hand, the developing sleeve 4a is installed in the coating container in parallel with the sponge roller 16. The developing sleeve is installed at a position where the longitudinal ends of the developing sleeve 4a are pressed by a rotatable bearing (not shown) in the direction of arrow B in FIG.
mm.

Sponge roller 16 and developing sleeve 4a
As shown in the figure, each of them rotates in the counter direction, and applies the lubricant 17 on the sponge roller 16 so as to rub it on the developing sleeve 4a. The amount of lubricant applied on the developing sleeve is determined by the amount of penetration of the developing sleeve into the sponge roller, the rotational speed and relative speed of each of the developing sleeve / sponge roller, and the absolute amount of the lubricant in the coating container 15. In order to apply a small amount, it is sufficient to apply only １ ／ to ４ of the sleeve 4a. In the present embodiment, the coating was performed for only 1/4 of the circumference of the sleeve 4a, and the coating amount was 1.0 mg / cm. Further, thereafter, in the assembling process, by applying a bias when rotating the sleeve 4a and developing the drum, the lubricant remaining on the sleeve 4a can be considerably reduced as a result. In an experiment, the total amount of the lubricant remaining on the developing sleeve 4a and the developing blade was set to 1.0 mg by this method.
/ Cm. When an image was formed in the same manner as in Example 1 using the process cartridge incorporating the developing sleeve thus obtained, good results were obtained.

[0049]

As described above, according to the present invention, in a process cartridge which is detachable from an image forming apparatus and in which a charging roller is driven to rotate with respect to a photosensitive member, a developing blade (or a developing As a lubricant to be applied to the sleeve, a substantially spherical polymer particle having an average circularity of 0.90 or more is used as a lubricant, and the lubricant in the longitudinal direction existing on the developer regulating member of the developing device and the developer carrier is used. When the coating amount of the agent is 0.23 to 1.40 mg / cm, the weight average particle diameter is more preferably larger than the developing sleeve surface roughness Rz.
If polymer particles of 0 to 30 μm are used as a lubricant,
Even when the process cartridge is vibrated or dropped in the shipping stage, the lubricant hardly adheres to the charging roller, so that the charging roller is not damaged and the vertical stripe-shaped charging failure does not occur. A developing device and a process cartridge using the same are provided. Further, according to the present invention, the initial developing sleeve torque at the start of use can be suppressed to a small value.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing experimental results according to the present invention.

FIG. 3 is a sectional view of a charging roller used in the present invention.

FIG. 4 is a schematic view showing a state in which a charging roller used in the present invention contacts a photosensitive member.

FIG. 5 is a schematic view illustrating a method of applying a lubricant to a developing blade.

FIG. 6 is a schematic view illustrating a method of applying a lubricant to a developing sleeve.

FIG. 7 is a diagram illustrating a configuration of a conventional image forming apparatus.

[Explanation of symbols]

 1, 101: photoreceptor 2, 102: charging roller 2a: cored bar 2b: conductive elastic layer 2c: resistance layer 3, 103: exposure device 4, 104: developing device 4a, 104a: developing sleeve 4b, 104b: developing blade 4c, 104c: Toner 5, 105: Transfer device 7, 107: Cleaning device 7a, 107a: Cleaning blade 8, 108: Fixing device 10: Lubricant containing solution 13: Charging bias supply power supply 15: Coating container 16: Sponge roller 17 : Lubricant 21: Bearing P: Transfer paper

Continuation of the front page (72) Inventor Satoru Motohashi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H077 AD06 AD13

Claims (4)

[Claims] An electrophotographic photoreceptor, a contact charging member held at both ends by bearing members, and configured to contact the photoreceptor under pressure to rotate following the photoreceptor; Developing device used in a process cartridge having a developer, a developer carrier, and a developing device in which a developer regulating member is provided, wherein the developer is present before the developer is put in and used. The lubricant is applied to the contact portion between the developer carrying member and the developer regulating member in a state where the lubricant has no average circularity of 0.90.
The application amount of the lubricant in the longitudinal direction, which is spherical polymer particles as described above and is present on the developer regulating member of the developing device and the developer carrier, is 0.23 to 1.40.
mg / cm. 2. The weight average particle diameter of the spherical polymer particles is larger than the surface roughness Rz of the developer carrier.
3. The developing device according to claim 1. 3. The spherical polymer particles are selected from silicone resin particles, PMMA (polymethyl methacrylate) particles, urethane-based elastic particles, acrylic resin particles, cross-linked polystyrene particles, and PVDF (polyvinylidene fluoride) resin particles. The developing device according to claim 1, wherein the developing device is at least one type. 4. A process cartridge in which at least an electrophotographic photosensitive member, a contact charging member, a developing device and a cleaning device are integrally incorporated, wherein the developing device according to any one of claims 1 to 3. A process cartridge, which is a developing device.