JPH0572883A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device for press-contact development, which has developer carrying and electrifying quantities suitable for development, and can stably form an image without having irregularities. CONSTITUTION:In the developing device for a press-contact developing system, a developer carrier 9 has structure so that an elastic layer 11 and a tube 12 are concentrically disposed on the outer periphery of a shaft 10, and the surface toughness Rz of the tube 12 is set 0.1-10 [mum] the coefficient of dynamic friction, is set 0.2-0.7, and wear resistance is set <=700[mg], in the abrasion test of JIS-K7311. Then, the product of the Young's modulus E of the tube 12, and film thickness (t) is <=12000. Further, the Young's modulus E of the tube 12 is set within some proper range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image formed on a latent image carrier with a developer formed as a thin layer on a developer carrier.

[0002]

2. Description of the Related Art As one of developing methods using a one-component developer, there is a pressure contact developing method as disclosed in USP3152012. In this method, a thin layer of developer is formed on a developer carrier, and then the electrostatic latent image formed on the latent image carrier is pressed by the developer thin layer to develop the visible image. The characteristics required of the developer carrying member are that a thin developer layer can be stably formed on the developer carrying member and that a soft contact with the latent image carrying member is possible. It becomes important.

As a method for stably forming a thin layer of a developer on a developer carrier in a conventional developing apparatus, as disclosed in JP-A-60-135966, friction on the surface of the developer carrier is known. The coefficient may be set to 0.5 to 0.7, or may be set in Japanese Patent Laid-Open No.
As disclosed in JP-A-8-214177, the surface roughness of the developer carrying member has been made 1 to 4 times the particle size of the developer.

Further, a developer carrier used in a conventional pressure-contact developing system developing device is composed of an elastic body and has a surface roughness as disclosed in JP-A-2-259785. By setting the Rz to 20 [μm] or less, a developer carrier which can be softly contacted with the latent image carrier and has a stable developer transporting ability can be obtained.

Further, as a method of enabling soft pressure contact with a latent image carrier and effectively obtaining a developing electrode effect, as disclosed in JP-A-1-191880, flexibility is provided outside the elastic layer. A method has been proposed in which a conductor layer is formed to be used as a developer carrier for pressure contact development.

[0006]

However, if the surface roughness and the coefficient of friction of the developer carrying member are not appropriate, the transporting property of the developer is deteriorated, and even if the surface roughness of the developer carrying member is small, for example. However, if the developer carrying member is made of a material having a large friction coefficient, the developer carrying amount becomes very large, and conversely, even if the developer carrying member has a small friction coefficient, It was found that when the surface roughness of No. 2 was increased, the amount of developer conveyed increased, resulting in an image with a lot of background fog.

When the surface of the developer carrying member has low wear resistance, the surface of the developer carrying member is abraded by rubbing against the developer, so that the surface roughness of the developer carrying member changes with time. However, there is a problem that a constant developer transport amount cannot be obtained over a long period of time.

Further, if the developer carrying member is made of a material having a low hardness, such as rubber, it is difficult to polish or roughen the surface, and it is very difficult to control the deviation of the outer diameter or the surface roughness. there were.

Further, if a flexible conductor layer is formed on the outer side of the elastic layer to form a developer carrying member, and the hardness of the elastic layer is lowered to realize soft contact with the latent image carrying member, the elasticity is improved. Development occurs due to the periodic vibration (so-called stick-slip phenomenon) that occurs when the developer carrier or elastic blade deforms at the contact part of the blade or the contact part with the photoconductor, and the distortion is released. There was a problem that the amount of agent conveyed and the amount of development varied.

Further, the low-hardness elastic layer is liable to cause a local compressive strain due to an abutting force of an elastic blade or the like, and even when the strain becomes a permanent strain or the compressive strain is recovered, the developer carrying member is carried. Takes a few rotations or more, so that the developer transport amount partially increases and the charge amount decreases, which causes fog in the background and uneven density.

Further, when a functional layer such as a conductive layer or a resistance layer is formed on the outer side of the low hardness elastic layer by a method such as coating or adhesion, the functional layer is pressed against the elastic blade or the latent image carrier. Since the layer is repeatedly subjected to compressive deformation, the functional layer must be provided with sufficient film strength and adhesion so that cracking of the functional layer and separation from the elastic layer do not occur, but in general, a resin containing carbon black dispersed therein. In addition, since the functional layer such as a metal thin film has low extensibility and flexibility, it may not be able to follow the deformation of the elastic layer and may be deformed.Also, the elastic layer may be made of a material with low surface energy such as silicone rubber. In this case, it was difficult to obtain sufficient adhesion between the functional layer and the elastic layer, and the functional layer was easily peeled off.

Therefore, the present invention solves such a problem, and an object of the present invention is to regulate the developer layer formed on the developer carrier to a transport amount and a charge amount suitable for development. The present invention is to provide a developing device that can be used.

Another object of the present invention is to prevent the surface of the developer carrying member from being significantly worn by sliding friction with the developer, and therefore, the developer carrying amount and charge amount can be stable for a long period of time. It is in the area of providing equipment.

Further, another object of the present invention is to perform the polishing process and the control of the surface roughness easily, so that the developer layer formed on the developer carrying member can be regulated to the transport amount suitable for the development. There is an agent device.

Still another object of the present invention is to prevent stick-slip and partial compression set of the elastic layer from occurring easily even when the hardness of the elastic layer constituting the developer carrying member is low, and therefore the developer is An object of the present invention is to provide a developing device in which the amount of conveyance and the amount of development do not easily change.

Still another object of the present invention is that the functional layer formed on the surface of the developer carrying member is less likely to undergo plastic deformation or fatigue fracture due to compressive deformation and has sufficient adhesion to the elastic layer. Another object is to provide a developing device having a long life and suitable for pressure development.

[0017]

A developing device of the present invention is a developing device for holding a developer layer formed in a thin layer on a developer carrying member and conveying it to a position facing a latent image carrying member. The developer carrier has a structure in which an elastic layer and a tube are concentrically arranged on the outer periphery of the shaft, and the surface roughness R of the tube is R.
z is 0.1 to 10 [μm].

Further, the dynamic friction coefficient between the outer surface of the tube and the developer layer is 0.2 to 0.7.

Further, there is provided a developing device for holding a developer layer formed as a thin layer on a developer carrying member and conveying the developer layer to a position facing the latent image carrying member, wherein the developer carrying member is provided on the outer periphery of the shaft. It has a structure in which an elastic layer and a tube are concentrically arranged, and the abrasion resistance of the tube is 700 [mg] or less in a JIS-K7311 abrasion test.

Further, the developing device holds a developer layer formed in a thin layer on the developer carrying member and conveys it to a position facing the latent image carrying member, wherein the developer carrying member is elastic on the outer periphery of the shaft. It has a structure in which layers and tubes are concentrically arranged, and the longitudinal elastic modulus E [kg / cm ² ] of the tube and the film thickness t [cm] of the tube satisfy the formula: E × t ≦ 12000. Characterize.

Further, in the developing device for holding a developer layer formed in a thin layer on the developer carrier and conveying it to a position facing the latent image carrier, the developer carrier is elastic on the outer periphery of the shaft. It has a structure in which layers and tubes are concentrically arranged, and the longitudinal elastic modulus E of the tube is expressed by the formula: 5 × r ³ / I ≦ E ≦ 40000 × r ³ / I [kg / cm ² ] I = π × (D ₁ ⁴ −d ₂ ⁴ ) / 64 r = (d ₁ + d ₂ ) / 4 π: Circularity d ₁ : Tube outer diameter [cm] d ₂ : Tube inner diameter [cm] Characterize.

[0022]

According to the above-mentioned structure of the present invention, the developer carrying member has a structure in which the elastic layer and the tube are concentrically arranged on the outer periphery of the shaft, and the surface roughness Rz of the tube is 0.1 to 1.
By setting the thickness to 0 [μm], the transport amount and the charge amount of the developer layer formed on the developer carrier can be prevented without causing the tube surface to be clogged with the developer or causing the developer to have a charging failure. It is suitable for development and can form an image with high density and less background fog.

Further, according to the above-mentioned constitution of the present invention, by setting the dynamic friction coefficient of the outer surface of the tube to 0.2 to 0.7, the carrying amount and the charging amount of the developer formed on the developer carrying member. Is suitable for development, and even when used for a long period of time, a high density and high resolution image can be stably formed without causing image defects such as density fluctuation and background fog.

Further, according to the above-mentioned constitution of the present invention, the abrasion resistance of the tube is set to 700 [mg] or less in the JIS-K7311 abrasion test, so that the surface of the developer carrier rubs against the developer. As a result, there is no significant abrasion, and therefore the surface roughness and the coefficient of friction do not change, so that the developer transport amount and the charge amount are stable over a long period of time.

Even if the elastic layer is made of a material having a low hardness that is hard to be ground, for example, foamed rubber, the surface is covered with a tube having an appropriate hardness, so that the surface is ground or roughened. It is possible to control the fluctuation of the outer diameter and the surface roughness easily.

In addition to the method of processing the tube in which the elastic layer is covered with the tube, the tube having the desired surface roughness can be covered with the elastic layer to obtain a very soft elastic surface. Even if it is a layer, the surface thereof can be easily put into a state suitable for development, and the tube processing itself is facilitated because it is not affected by the elastic layer.

Generally, when the surface of a tube is subjected to surface processing such as polishing or roughening, if the hardness is too low, the workability is deteriorated, and if the tube is too hard, the tube is flexible. Of the tube, a sufficient nip width cannot be obtained at the contact portion with the photoconductor, and fatigue fracture occurs at the portion where bending stress is repeatedly applied. However, the longitudinal elastic modulus of the tube is E [kg / cm ² ]. The film thickness t [cm] of the tube is
If the formula: E × t ≦ 12000 is satisfied, the rigidity of the tube can be improved within the range of sufficient flexibility, and fatigue fracture does not occur due to repeated stress. It is suitable as a developer carrier for pressure development that is exposed to deformation. Also, since it is possible to give the tube sufficient flexibility,
If the elastic layer is made to have a low hardness, soft contact with the latent image bearing member becomes possible, and the contact width with the elastic blade and the latent image bearing member can be widened so that the charge amount of the developer can be improved and high-speed printing can be performed. It will be possible. Further, since the rigidity of the tube can be made in a good workability state, the surface roughness and the coefficient of friction of the tube can be easily made suitable for development, and therefore, the transport amount of the developer and the charge amount can be stabilized and the background fog can be prevented. An image with little density fluctuation can be formed.

Further, according to the above-mentioned structure of the present invention, the developer carrying member has a structure in which the elastic layer and the tube are concentrically arranged on the outer periphery of the shaft, and the longitudinal elastic modulus E of the tube is set.
Is the formula: 5 · r ³ / I ≦ E ≦ 40000 · r ³ / I [kg / cm ² ] I = π × (d ₁ ⁴ −d ₂ ⁴ ) / 64 r = (d ₁ + d ₂ ) / 4 π: Circularity d ₁ : Tube outer diameter [cm] d ₂ : Tube inner diameter [cm] Satisfying the elastic blade and the photoconductor even when the hardness of the elastic layer is very low. Since the contact pressure can be effectively dispersed by the rigidity of the tube, periodic micro-vibration (stick slip) that occurs when releasing locally generated compressive deformation and partial compression set of the elastic layer are generated. Can be prevented, so that the amount of developer conveyed and the amount of charge can be stabilized, and an image with little density fluctuation can be formed.

Even when a functional layer such as a magnetic field generating layer is provided on the surface of the tube, since the tube does not locally undergo large deformation, the functional layer may be peeled or cracked due to compressive deformation or the like. In addition to making it difficult, the selection of materials that can be used for the tube is wide, so it is possible to facilitate the placement of the functional layer, for example, by using materials of the same system as the magnetic paint to improve adhesion with the magnetic paint. it can.

The present invention will be described in detail below with reference to examples.

[0031]

【Example】

(Embodiment 1) FIG. 1 is a schematic cross-sectional view of a developer carrying member used in a developing device in an embodiment of the present invention, in which a conductive elastic layer 11 and a conductive elastic layer 11 are provided on the outer periphery of a conductive shaft 10. A tube 12 having conductivity is provided concentrically, and the tube 12 has carbon black 22 as conductive particles dispersed in a binder 21 to impart conductivity, and the layer thickness thereof is a dispersion of these. Therefore, it is set to 3 [mm] or less, preferably 0.5 [mm] or less so as to have sufficient flexibility even if the hardness of the tube increases. Even when the agent carrier 9 is brought into pressure contact with a latent image carrier (not shown) for development, the pressure contact pressure is effectively alleviated by the elastic layer 11 and soft contact is made possible. An image can be formed without damage or solidification of the developer. It

FIG. 2 is a schematic sectional view of the developing device of the present invention. The latent image carrier 1 is a conductive support portion 2 coated with a photosensitive layer 3 having organic or inorganic photoconductivity, and the photosensitive layer 3 is charged by a corona charger or a charging roller. After being charged by using the container 4, light emitted from a light source 5 such as a laser or an LED is selectively irradiated to the photosensitive layer 3 according to an image through an imaging optical system 6 to obtain a potential contrast to obtain an electrostatic latent image. Form an image. On the other hand, the developing device 7 conveys the developer 8 and develops it.
7 and the developer carrying member 9 are rubbed against each other to impart triboelectrification and hold on the developer carrying member 9 by electrostatic force,
After the charge amount is adjusted by the elastic blade 13 in the shape of a thin leaf spring made of a non-magnetic or magnetic metal or resin to make a proper amount of thin layer, the developer carrier 9 is rotated to convey the thin layer of developer. It is a thing. The developer 8 on the developer carrying member 9 is formed by the potential contrast of the latent image carrying member 1 and the developing bias applying means 14 when it is conveyed to the pressure contact portion between the developer carrying member 9 and the latent image carrying member 1. Latent image carrier 1 according to the developing electric field
And the electrostatic latent image is visualized. Further, an image formed by the developer is transferred onto the recording paper 16 by using the transfer device 15 such as a corona transfer device or a transfer roller, and the developer is fixed on the recording paper by using heat or pressure to form a desired image on the recording paper. I will get it.

FIG. 3 is an explanatory diagram showing the developing characteristics of the developing device of the present invention.

FIG. 3A shows the surface roughness Rz of the tube.
FIG. 3 is an explanatory diagram showing a relationship between [μm] and a dynamic friction coefficient μ _k ,
It is divided into the following five areas depending on the developer carrying capacity and the developer charge amount.

Region 1: developer transport amount and charge amount good region Region 2: developer transport amount insufficient region Region 3: developer charge amount insufficient region Region 4: unstable region 1 region 5: unstable region 2 In a), region 1 is a region where both the surface roughness and the coefficient of dynamic friction of the tube are appropriate, and no fusion of the developer or clogging of the surface is observed, and the developer is stably conveyed over a long period of time. Therefore, a good image without background fog and insufficient density can be stably formed. In the area 2, both the surface roughness and the dynamic friction coefficient are small, and the ability to hold and convey the developer on the tube surface is low, so that an image with insufficient density can be formed, which is not preferable. In the area 3, both the surface roughness and the coefficient of dynamic friction are large, and the developer carrying capacity is too large, so that an excessive amount of the developer is carried, and as a result, the developer charge amount is lowered and the background fog is likely to occur, which is not preferable. .. Region 4 has a very smooth surface state and an appropriately large dynamic friction coefficient, and a good image can be initially formed, but the developer is likely to stick to the surface of the tube or become clogged, and stable for a long period of time. It is difficult to form an image. Area 5 is
A good image can be initially formed with a low dynamic friction coefficient and a moderately large surface roughness, but the amount of conveyance easily fluctuates due to changes in the remaining amount of developer and fluidity, so images are stable over a long period of time. Is difficult to form.

FIG. 3 (b) is the same as A in FIG. 3 (a).
For the three types of tubes having the relationship between the surface roughness and the dynamic friction coefficient shown by B and C, the surface roughness Rz [μ
FIG. 3 is a diagram showing a relationship between a developer conveyance amount [mg / cm ² ] and a developer charge amount [μc / g] with respect to m].

In FIG. 3 (b), the developer carrying member coated with the tube A cannot obtain a sufficient developer carrying force in the region where the surface roughness Rz is 0.1 [μm] or less, and the density is low. When the surface roughness Rz is 10 [μm] or more, a sufficient amount of developer charge cannot be obtained, resulting in an image with a lot of background fog, and there is no background fog in the dynamic friction coefficient range of 0.2 to 0.7 and the density is high. Was obtained a sufficient image.

The developer bearing member having the tube B adhered thereto has a surface roughness Rz of 0.05 [μm] or less and the developer conveyance amount is insufficient, resulting in an insufficient density image, and a coefficient of dynamic friction of 0.75 or more. In the area, the background fog occurs due to the insufficient charge amount of the developer, and in the area where the surface roughness Rz is 0.05 to 0.1 [μm] and the dynamic friction coefficient is 0.7 to 0.75, a good image is initially obtained. Was formed, but filming occurred, which is not preferable, and an image with good density and resolution can be formed in the region where the surface roughness Rz is 0.1 [μm] or more and the dynamic friction coefficient is 0.7 or less. It was

The developer-carrying member coated with the tube C has a kinetic friction coefficient of 0.1 or less, an insufficient amount of developer conveyed, resulting in an image of insufficient density, and a surface roughness Rz of 30 [μm] or more. Ground fog occurs due to insufficient charge amount, and a region having a dynamic friction coefficient of 0.1 to 0.2 and a surface roughness Rz of 10 to 30.
In the range of [μm], the developer transport amount and the charge amount are easily changed depending on the remaining amount of the developer and the fluidity, which is not preferable, and the dynamic friction coefficient is 0.2 or more and the surface roughness Rz is 10 or more.
In the region of [μm], an image with good density and resolution could be stably obtained.

As a result of many experiments in addition to the above-described transporting experiment of the developer carrying member coated with the three types of A, B, and C tubes, the surface roughness Rz of the developer carrying member was set to 0. 1
When it is [μm] or more, the surface of the developer carrying member is less likely to be clogged, and the developer can be stably conveyed. When the surface roughness Rz is 10 [μm] or less, the charge amount of the developer is sufficient. It is possible to obtain a high image with less background fog. Also, the surface roughness R of the surface of the developer carrying member
By setting z to 0.1 to 10 [μm] and the dynamic friction coefficient to the developer to 0.2 to 0.7, the development can be performed regardless of the remaining amount of the developer in the developer hopper and the fluctuation of the fluidity of the developer. The agent can be stably transported, and the filming of the developer does not occur on the surface of the tube even when it is used for a long period of time, and a high-concentration image free of background fog can be stably formed.

In this embodiment, a one-component non-magnetic developer having a volume average particle size of 10 [μm] is used as the developer, and a thickness of 0.1 [m] is used as the developer transport amount regulating member.
m], a surface roughness Rz of 0.05 [μm], and an urging (regulating) force of 1 [kg], a stainless elastic blade was used. When the biasing force of the elastic blade is strong, it becomes difficult for the developer to pass under the elastic blade. Therefore, the surface roughness or the coefficient of friction of the developer carrier is increased to increase the developer carrying capacity. It is necessary, for example, if the biasing load of the elastic blade is about 1.5 [kg], the surface roughness Rz of the developer carrying member is preferably about 3 [μm]. Further, the smaller the particle size of the developer becomes, the more difficult it is to regulate the amount of developer conveyed, and therefore the surface roughness of the developer carrier needs to be reduced.

In the present embodiment, the dynamic friction coefficient μ _k between the developer carrier and the developer layer was measured by a parallel plate shear tester (PTHN-13BA type: Sankyo) as shown in FIG. 3 (c). (Manufactured by Dengyo Co., Ltd.) is used, and more specifically, a developer layer of 4 [mm] is formed in the gap between the two shear fixing plates 31 having the tubes 12 attached to the surface, and the vertical stress σ Is calculated from the shearing force τ when 100 [gf / cm ² ] is applied.

Further, the developer carrying member 9 used in this embodiment is formed by integrally molding the elastic layer 11 made of foamed silicone rubber on the outer circumference of the stainless steel shaft 10 by the LTV method. Is carbon black 4 [wt
%], It is made conductive with a volume resistivity of about 10 ⁵ [Ω · cm], and the rubber hardness is 40 degrees as measured by an Asker C type hardness meter.

The tube 12 is a conductive and flexible tube in which conductive particles are dispersed in a binder,
More specifically, it is a tube formed by extruding carbon black 6 [wt%] in a polyurethane resin to have a volume resistivity of 10 ⁴ [Ω · cm] and a film thickness of 50 [μm].
The outer surface thereof is sandblasted so that the surface roughness Rz becomes 2 [μm], and the coefficient of dynamic friction is 0.4.

The conductive and heat-shrinkable tube 12 coated on the outer periphery of the elastic layer 11 is firmly held on the elastic layer 11 by its gripping force, so that the surface between the heat-shrinkable tube surface and the shaft is Conduction is ensured, and development can be performed by applying a development bias voltage to the shaft.

The inner diameter of the tube 12 before heat shrinkage is φ22.
[Mm], after inserting the elastic layer 11 inside the tube 12 before heat shrinking, decompressing the environment, and further 120 [° C.]
Then, the tube 12 is shrunk to cover the outer circumference of the elastic layer 11 to obtain a developer carrying member.

The binder 21 constituting the tube 12
Is a polyurethane resin, vinyl chloride, fluororesin, polyethylene, polypropylene, polyester, polyamide resin, polyolefin, epoxy resin, vinyl copolymer resin such as vinyl acetate, vinyl alcohol, vinyl butyral, vinyl formal, vinyl ethyl ester, or Polyamide or nitrocellulose or cellulose acetobutyrate or a blend of these with other resins can be used, for example, by blending vinyl acetate, vinyl chloride and polyurethane, or by blending cellulose acetobutyrate and vinyl formal. It is possible to design binders that complement each other's characteristics and have both dispersibility and mechanical strength.
DM, fluorine rubber, silicone rubber, chloroprene rubber,
Any material having elasticity or flexibility such as natural rubber, isoprene rubber, butadiene rubber, neoprene rubber, rubber such as NBR, etc. can be used as the binder. In addition, as the conductive particles dispersed in the tube 12, it is preferable that the conductive particles are sufficiently conductive even if added in a small amount and the flexibility of the tube is not easily deteriorated. For example, conductive carbon black is preferable. The carbon black has the ability to form a strong structure, and it is desirable that the carbon black acts so as to significantly reduce the electric resistance as the amount of carbon black added increases. For example, Ketjen black, acetylene black, lamp black, High-structure furnace black or the like can be used, and acetylene black or the like having particularly good conductivity is suitable, and a smaller particle size is preferable in order to reduce the conductivity because a large surface area per unit amount can be obtained.

As a method of manufacturing the tube 12,
Extrusion molding method, compression molding method, transfer molding method, injection molding method, vacuum molding method, blow molding method, etc. can be used,
Particularly, according to the extrusion molding method, since a tube having a constant film thickness can be continuously manufactured, the manufacturing cost can be reduced, and the surface roughness Rz of the extrusion mold is 0.1 to 10 [μ].
m] makes it possible to impart a desired surface roughness to the surface of the tube, so that surface treatment such as sandblasting can be omitted, which is particularly desirable for manufacturing an inexpensive developer carrying member.

The material forming the shaft 10 is a conductive material such as a resin in which a conductive powder such as stainless steel, steel, copper, aluminum or carbon black is dispersed when a developing bias is applied from the shaft for development. It is possible to use a material that has sufficient bending strength against the pressure contact force.

The material forming the elastic layer 11 needs elasticity to relieve the pressure contact pressure with the latent image carrier, and its hardness is 80 degrees with an Asker C type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.). The following is preferable, and 50 degrees or less is more preferable in order to prevent deterioration of the developer. Urethane rubber, silicone rubber, fluororubber, EPDM, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber,
Polysulfide rubber, butyl rubber, chloroprene rubber, natural rubber, isoprene rubber, butadiene rubber, neoprene rubber, NBR, etc. can be used in the form of rubber, foam or a roller having a skin layer on the outer periphery of the foam, and Polyurethane resin, styrene resin, vinyl chloride resin, polyethylene resin, methacrylic resin, and all other resins that can be formed into elastic foam, and elastomers and other resins that have a large amount of elastic deformation and a short recovery time to the original state Can be used.

In order to dispose the elastic layer 11 on the outer periphery of the shaft 10, in addition to the method of integrally forming the shaft and the elastic layer, the elastic layer is preliminarily formed into a hollow cylindrical shape and is disposed by fitting or bonding. You can

(Embodiments 2 to 6) FIG. 4 is a schematic cross-sectional view and a mechanical characteristic explanatory view of a developer carrying member used in a developing device in another embodiment of the present invention. Members having substantially the same names and functions as those of No. 1 are given the same numbers and their explanations are omitted. In FIG. 4A, the developer carrying member 9 is formed by integrally forming a foamable elastic layer 11 made of silicon rubber on the outer circumference of a stainless steel shaft 10.
Has a skin layer 42 that is naturally formed on the outer periphery of the foam layer 41 in the portion that was in contact with the molding die, and has a volume resistivity of 1% by dispersing carbon black 3 [wt%].
It is made conductive to about 0 ⁵ [Ω · cm], and the rubber hardness is 25 degrees with an Asker C type hardness meter.

The outer circumference of the elastic layer 11 is covered with a conductive and heat-shrinkable tube 12, and the heat-shrinkable tube 12
Is adhered onto the elastic layer 11 with a conductive adhesive, the conduction between the surface of the heat-shrinkable tube and the shaft is secured, and development can be performed by applying a development bias voltage to the shaft.

The inner diameter of the tube 12 before the heat shrinkage is φ24.
[Mm] and the outside diameter φ inside the tube 12 before heat shrinkage.
After inserting the elastic layer 11 having a diameter of 20.5 [mm], the environment is decompressed and further heated to shrink the tube 12, and the outer periphery of the elastic layer 11 is covered to provide a developer carrying member having an outer diameter of 20 [mm]. And

The tube 12 is a conductive and flexible tube in which conductive particles are dispersed in a binder,
More specifically, 6 [wt of carbon black in the binder
%] Dispersed volume resistivity of about 10 ⁴ [Ω · cm], film thickness of 50
It is a tube formed by extrusion molding of [μm], the outer periphery of which is sandblasted so that the surface roughness Rz is 2 [μm], and the coefficient of dynamic friction is 0.4.
It is 5.

In the present embodiment, the developer carrying member having the abrasion resistance of the tube changed is used in the developing device shown in FIG. 2 to form an image, and more specifically, the binder constituting the tube. A different material was used to carry out a durability printing test for each developer carrying member, and the surface roughness and the printing image quality were evaluated.

The volume average particle size of the developer is 10 [μ
m], a one-component magnetic developer having a magnetic powder content of 20 [wt%] was used, and an image was formed with an urging load of the developer carrier to the latent image carrier of 1 [kg].

Table 1 shows that the number of A4 size sheets printed is 50.
The 10-point average roughness Rz of the surface of the tube 12 at the time of 00 sheets, 10000 sheets, 20000 sheets and 50000 sheets and the image quality evaluation results of the line image and the solid image formed on the latent image carrier are shown. In Table 1, the amount of wear is JI
It shows the amount of wear of the tube 12 by the S-K7311 wear test (wear wheel H22, 1000 rotation wear).

[0059]

[Table 1]

As a result, in Examples 2 to 6, a line image of 600 [DPI] was formed on the latent image carrier 1 without being crushed, and a high density solid having an OD value of 1.4 or more. An image could be formed. Furthermore, A4 size paper 5
Even after forming 0000 images, a line image of 600 [DPI] can be formed on the latent image carrier without being crushed, and a high-density image having an OD value of 1.4 or more can be formed. The decrease in density of the solid image was also 0.1 or less.

Comparative Examples 1 and 2 In this comparative example, JIS-K731 is used as the tube 12 which constitutes the developer carrying member 9.
The durability printing test was conducted in the same manner as in Examples 2 to 6 by using one having an abrasion amount of 700 [mg] or more by the abrasion test. The surface of the tube 12 was sandblasted so that the surface roughness Rz was 2 [μm].

Table 2 shows the types of binders constituting the tube 12 used in this comparative example, JIS-K731.
1 Abrasion amount of tube by abrasion test, and 5000 sheets, 10,000 sheets, 20,000 sheets, 50 sheets of A4 size paper
The surface roughness after printing 000 sheets and the image quality evaluation result of a printed image are shown.

[0063]

[Table 2]

As a result, initially, a 600 [DPI] line image was formed on the latent image carrier 1 without being crushed, and a high-density image having an OD value of 1.4 or more could be formed. However, in Comparative Example 1, when images equivalent to 20000 sheets of A4 size paper were continuously formed, the surface of the tube 12 was abraded, and as a result, a sufficient developer transport amount could not be obtained. It became impossible to form a solid image having a high image density.

Further, in Comparative Example 2, the surface of the tube 12 was worn when images corresponding to 5000 A4 size sheets were continuously formed, and the density of the solid image was not sufficient. When I continued printing,
Innumerable streak-like scratches are generated in the circumferential direction of the tube 12, the developer is locally fused on the surface of the tube, and the formed image has a lot of background fog and a line of 600 [DPI]. The image is crushed. FIG. 4 (b) shows the change over time in the amount of wear of the tube using acrylic resin as the binder, and FIG. 4 (c) shows the relationship between the amount of wear on the surface of the tube and the surface roughness Rz. .. The tube surface is constantly rubbed through the developer particles at the position facing the elastic blade and the electrostatic latent image carrier,
As shown in FIG. 4 (b), the surface wears with the lapse of time, and as a result, as shown in FIG. 4 (c), the surface roughness Rz sharply decreases as the amount of wear increases, In particular, since the amount of wear of the tube was large immediately after the use of the developer carrying member, the initial change in the developer carrying amount was large.

Therefore, if a tube having low abrasion resistance is used on the surface of the developer carrying member, the surface of the tube will not be developed even if the developer carrying amount and charge amount suitable for developing are initially obtained. If the tube is worn away while being rubbed with the agent, and the surface roughness and the coefficient of friction of the tube are not suitable for carrying the developer or imparting charge, an image with insufficient density is formed. Further, when the tube is scratched or the like, the amount of developer conveyed becomes non-uniform, which causes an image with a lot of background fog and a reduction in fine line reproducibility.

From the above, the material of the tube for coating the elastic layer is determined by the JIS-K7311 wear test (wear wheel H22, 1).
000 rotations), the amount of wear is 700 mg or less, so that the tube surface will not be easily worn away even when the developer is severely rubbed, and the surface roughness will be long-term. It was possible to obtain a constant developer carrier, and thus it was possible to stably obtain an image having a sufficient image density and good resolution. In addition, by setting the amount of wear of the tube to 200 [mg] or less in the wear test, it is possible to reduce the large amount of wear of the tube that occurs initially, and thus, to prevent the developer carrier from being used for a long period of time. It is now possible to obtain images with little density fluctuation.

The material of the tube is polyurethane, fluororesin, polyethylene, nylon, polycarbonate, vinyl chloride, etc., and the wear amount is 700 [mg] in the JIS-K7311 wear test (wear wheel H22,100).
Polyurethane having a wear amount of 200 [mg] or less and having sufficient flexibility is particularly preferable.

(Embodiment 7) FIG. 5 is a schematic cross-sectional view of a developer carrying member used in a developing device in another embodiment of the present invention. The same numbers are given to the members and the description thereof is omitted. In FIG. 5A, the developer carrying member 9 is formed by integrally molding an elastic layer 11 made of urethane foam on the outer circumference of a shaft 10 made of stainless steel. The elastic layer 11 is made of carbon black 7 [wt.
%], It is made electrically conductive to have a volume resistivity of about 10 6 Ω · cm, and the rubber hardness is 37 degrees as measured by an Asker C type hardness meter.

A conductive tube 1 is provided on the outer circumference of the elastic layer 11.
2, the tube 12 is coated with a material that easily charges the developer to a desired polarity, has good abrasion resistance, and is easy to control the surface roughness, for example, carbon black dispersed in a conductive material. In the case of the tube provided with the above, since the tube surface and the shaft can be electrically connected, it is possible to apply the developing bias voltage to the shaft to perform the developing. The outer circumference of the tube 12 is sandblasted so that the surface roughness Rz is 5 [μm], and the coefficient of dynamic friction is 0.6.

The tube 12 is formed in advance into a sleeve shape having an outer diameter of 20 [mm] and a thickness of 50 [μm] by extrusion processing, and the elastic layer 1 having an outer diameter of 21 [mm].
1 is fitted inside the tube 12 while being elastically deformed to form a developer carrying member.

Since the elastic layer 11 is a foamed material, its hardness can be greatly reduced, so that the pressure contact force with the photosensitive member can be effectively alleviated to allow soft contact, and the developer carrying agent for pressure contact development can be carried. Although the form of the body is desirable, if the developer is directly conveyed on the surface, a large amount of the developer is conveyed by the cells exposed on the surface of the elastic layer. Will end up. In the present invention,
By covering the outer peripheral surface of the elastic layer 11 with a tube, the surface state can be easily processed to have a surface roughness suitable for the developer transport regardless of the cell density of the foam, so that the stable developer transport is always performed for a long period of time. It has become possible to go to.

As the form of the elastic layer 11, in addition to the foam as shown in FIG. 5 (a), very low hardness rubber or thermoplastic elastomer can be used, but generally low hardness rubber. Is difficult to perform polishing, and a grinding mark having a 10-point average roughness Rz of 30 [μm] or more is likely to occur as shown in FIG. 5B, and the developer is clogged in the grinding mark to cause an excessive amount of development. This may cause the agent to be conveyed or the filming of the developer to occur. Even in this case, if the outer circumference of the elastic layer is covered with a tube as in the present invention, the surface state can be easily processed to have a proper surface roughness for developer transport regardless of the grinding marks of the elastic layer. Even if the elastic layer is a foam or has a low hardness such that polishing processing is difficult to perform, it is possible to always carry out stable developer transport for a long period of time. Further, since the roughness of the surface of the developer carrying member can be processed by the tube alone, the surface roughness can be easily controlled without being affected by the elastic layer.

(Examples 8 to 19) FIG. 5A is a schematic cross-sectional view of a developer carrying member used in a developing device in another example of the present invention, and is substantially the same as that in Example 1. The members having the same names and the same functions are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 5A, the developer carrying member 9 is
An elastic layer 11 made of expandable silicone rubber is integrally formed on the outer circumference of a stainless steel shaft 10.
The outer circumference of 1 is further covered with a tube 12.

Since the outer circumference of the elastic layer 11 is covered with the tube 12, even if the elastic layer 11 is made of a member such as foam having a cell opening on the surface, the developer is clogged in the cell. Does not cause background fog, and even if the elastic layer is made of a material with poor abrasiveness such as low hardness rubber, the surface state of the developer carrier is irrespective of the grinding marks of the elastic layer. Can be easily processed to have a surface roughness suitable for carrying the developer, so that the developer can always be carried stably. Furthermore, when a large amount of plasticizer is added to the elastic layer in order to reduce the hardness of the developer carrier, the plasticizer gradually exudes to the surface of the developer carrier and loses elasticity of the elastic layer. The tube may be coated on the outer circumference of the elastic layer, although it may be damaged or the plasticizer may seep into the developer, causing deterioration of the charging performance and fluidity of the developer and filming on the surface of the developer carrier. This can prevent the plasticizer from seeping out to the surface of the developer carrier, and prevent the filming of the developer and the increase in hardness of the elastic layer.

Since the developer carrying member in this embodiment is used in a state of being pressed against the latent image carrying member, the tube covering the surface of the elastic layer is sufficiently large so as not to lose the elasticity of the developer carrying member. It is necessary to have sufficient flexibility and to prevent fatigue failure against repeated compressive stress.

However, in general, when the surface of the tube is subjected to surface processing such as polishing or roughening, if the hardness is too low, the workability is deteriorated, and if the tube is too hard, it is possible. Flexibility deteriorates and fatigue fracture occurs when bending stress is repeatedly applied.

In this example, the longitudinal elastic modulus E [kg / cm 2] of the tube covering the elastic layer and the film thickness t
The durability printing test was performed on 50,000 sheets of A4 size paper by changing various [cm]. For the printing test, the volume average particle size is 10
A one-component magnetic developer having a magnetic powder content of 20 [wt%] was used, and the biasing load of the developer bearing member against the latent image bearing member was 1 [kg]. The outer diameter of the tube was set to 20 [mm]. Table 3 shows the results of the durability printing test.

In Table 3, "A" in "Evaluation" indicates that the tube did not break even after printing 100,000 sheets of A4 size paper, and the filming of the developer did not occur on the tube surface. The case where an image can be formed with good density and fine line reproducibility is shown. Also, ○ indicates that the tube does not break after printing 100,000 sheets of A4 size paper, but the filming of the developer occurs on the surface of the tube when printing of about 20,000 sheets is completed. Indicates.

[0081]

[Table 3]

In this embodiment, 60 is formed on the latent image carrier.
An image of 0 [DPI] is formed without being crushed, and the tube does not undergo fatigue damage even after printing 100,000 sheets of A4 size paper. Therefore, the roller coated with a tube on the surface of the elastic layer is used as a developer. Even with the carrier, the pressure contact development could be well performed.

(Examples 20-27) In this example, the longitudinal elastic modulus E [kg /
cm ² ], the tube film thickness t [cm], and the tube outer diameter d [cm] were variously changed, and a durability printing test was performed on 100,000 sheets of A4 size paper.

[0084]

[Table 4]

In the printing test, the volume average particle size is 10 [μ
m], a one-component magnetic developer having a magnetic powder content of 20 [wt%] was used, and the biasing load of the developer carrying member against the latent image carrying member was 1 [kg]. The outer diameter of the tube was set to 20 [mm].

The results of the durability printing test are shown in Table 4. Table 4
Medium, "A" in "Evaluation" indicates that the tube does not break even after printing 100,000 sheets of A4 size paper.
Further, the case is shown in which the filming of the developer does not occur on the surface of the tube, and an image can be formed with good image density and fine line reproducibility. In addition, ◯ indicates that the tube does not break after printing 100,000 sheets of A4 size paper, but about 5
The case where the filming of the developer occurs on the surface of the tube at the time when the printing of ten thousand sheets is completed is shown.

In this embodiment, the outer diameter is 0.5 to 5 [c
When the image is formed on the developer carrier using the tube of m], the image of 600 [DPI] is formed on the latent image carrier without crushing, and 100,000 sheets of A4 size paper are durable printed. Even after that, the tube was not fatigue-damaged, and therefore the pressure development could be favorably carried out even if the roller having the surface of the elastic layer coated with the tube was used as the developer carrying member.

(Examples 28 to 31) This example is shown in FIG.
A developer carrier having a structure in which an elastic layer and a tube are concentrically formed on the outer circumference of a shaft as shown in (a),
When an image was formed while pressing the latent image carrier with a biasing load of 1 [kg], a durability printing test was performed by changing the film thickness of the tube, and the image defect and the tube state were observed. ..

In this example, silicon rubber was used as the elastic layer, a nickel electroformed tube with an outer diameter of 10 mm was used as the tube, and silicon rubber was foamed inside the nickel electroformed tube for integral molding. A developer carrier was used.

The results of the durability printing test are shown in Table 5. Table 5
Medium, "Stress S" means that when the tube is pressed against the photoconductor,
The maximum bending stress S [kg / cm ² ] generated in the tube is shown. In Table 5, "A" in "Evaluation" indicates that the tube did not break even after the developer carrying member rotated 10 ⁶ times, and the filming of the developer did not occur on the tube surface, and the image density and fine line reproduction were reproduced. The case where an image having good properties can be formed is shown. Further, ◯ indicates a case where the tube was not broken after the developer carrying member was rotated 10 ⁶ times, but filming of the developer occurred on the surface of the tube.

[0091]

[Table 5]

In Examples 28 to 31, the durability printing test was conducted by changing the tube thickness t.
A high-density image having a D value of 1.4 or more is stably formed, and the tube does not undergo fatigue fracture even after 10 ⁶ rotations of the developer carrying member. Therefore, the surface of the elastic layer is covered with the tube. Even when the roller was used as the developer carrying member, the pressure contact development could be well performed. Furthermore, the longitudinal elastic modulus E [kg / c
m ² ] and the film thickness t [cm] of the tube E × t is 900
When it is 0 or less, an image of 600 [DPI] can be formed on the latent image bearing member without being crushed even after the developer bearing member rotates 10 ⁶ times, and an image with good fine line reproducibility is formed for a long period of time. Was especially desirable for.

In this embodiment, a nickel electroformed tube is used as the tube. However, even when a resin such as polyurethane or vinyl chloride is used, Ext is 12000.
If the conditions are as follows, the tube was not broken even when the developer carrying member was used for 10 ⁶ rotations or more, and the pressure development was satisfactory.

(Comparative Examples 3 to 6) Comparative Examples 3 to 6 correspond to Examples 28 to 31, and change the longitudinal elastic modulus E [kg / cm ² ] and the film thickness t [cm] of the tube. Then, the durability printing test was performed, and the image defect and the state of the tube were observed.

FIG. 6 is an explanatory view of the mechanical characteristics of the tube which constitutes the developer carrier used in the developing device in this comparative example, and shows the elasticity of the outer circumference of the shaft as shown in FIG. 5 (a). The maximum amount that occurs in the tube when image formation is performed with the developer carrier having a structure in which the layers and the tube are concentrically formed is pressed against the latent image carrier with a biasing load of 1 [kg]. The relationship between the bending stress S [kg / cm ² ] and the number of bendings (rotation speed of the developer carrying member) N at which the tube causes fatigue failure is shown. In this comparative example, a silicone rubber was used as the elastic layer, a nickel electroformed tube was used as the tube, and the outer diameter of the developer carrying member (outer diameter of the tube) was 10 mm.

Table 6 shows the results of the durability printing test. Table 6
Medium, "Stress S" means that when the tube is pressed against the photoconductor,
The maximum bending stress S [kg / cm ² ] generated in the tube is shown. In Table 5, “X” in “Evaluation” indicates that the tube constituting the developer carrying member was fatigue-broken due to repeated stress during the durability printing test, and the image formation could not be continued. Further, Δ indicates that the tube did not break after the developer carrying member rotated 10 ⁶ times, but the tube was deformed to give an image with uneven density, or filming of the developer on the tube occurred. Therefore, it is impossible to form a high-resolution image, and fatigue failure occurs when the durability printing test is further continued.

[0097]

[Table 6]

In Comparative Example 3 and FIG. 6, the film thickness is 0.00
When a tube was formed of a nickel electroformed tube of 8 cm and pressure development was performed, the maximum bending stress generated in the tube was 1680 [kg / cm ² ]. Further, when a durability printing test was conducted using this developer carrying member, the tube was repeatedly fatigue-damaged by stress when the developer carrying member was rotated about 10 ⁵ times.

In Comparative Example 4 and FIG. 6, the film thickness is 0.00
When the tube was constructed of a nickel electroformed tube of 6 [cm] and pressure development was performed, the maximum bending stress generated in the tube was 1260 [kg / cm ² ]. Further, a durability printing test was conducted using this developer carrier, and the tube was not broken after the developer carrier was rotated about 10 ⁶ times, but the tube was deformed and an image with uneven density was obtained. Also, the filming of the developer occurs on the tube, and it becomes impossible to form a high-resolution image. Further, when the durability printing test was continued, the tube soon suffered fatigue failure due to repeated stress.

Therefore, the elastic layer and the tube are concentrically formed on the outer periphery of the shaft to form a developer carrying member for pressure contact development, and the product (E × t) of the longitudinal elastic coefficient E of the tube and the film thickness t of the tube is obtained. If it is 12,000 or less, the diameter of a general developer carrier is 0.5 to 5 [cm] and the biasing load (linear pressure) on the latent image carrier is 0 to 200 [g / cm],
The tube formed on the surface of the developer bearing member will not be fatigue-broken due to repeated bending stress applied to the tube during pressure contact development. Also, even if the elastic layer is made of a material whose surface shape is difficult to control, such as foam or low hardness rubber,
By covering the outer circumference of the elastic layer with a tube, the surface of the developer carrier can be easily processed into a state suitable for transporting the developer, and furthermore, the tube does not undergo fatigue failure due to repeated bending stress. It is possible to obtain a developer carrier suitable for development.

Further, an elastic layer and a tube are concentrically formed on the outer circumference of the shaft to form a developer carrier for pressure contact development, and the product of the longitudinal elastic coefficient E of the tube constituting the developer carrier and the film thickness t ( When E × t) is 9000 or less, the developer is less likely to cause filming on the surface of the developer carrier even when the image is formed for a long time, and the image formation with sufficient density can be stably performed. Became.

From the above, (EX) is applied to the outer periphery of the low hardness elastic layer.
By coating the tube whose t) is 12000 or less,
A developer carrier capable of making a soft contact with the latent image carrier and ensuring a wide development nip is obtained. Therefore, the developer solidifies or filming occurs on the developer carrier. It is possible to obtain an image with less density unevenness at high speed without causing damage to the latent image carrier.

(Embodiments 32 to 38) FIG. 7 is a schematic cross-sectional view of a developer carrying member used in a developing device in another embodiment of the present invention. The same number is attached to the member of and the description thereof is omitted. In FIG. 7A, the developer carrying member 9 is a stainless steel shaft 10.
An elastic layer 11 (longitudinal elastic modulus = 8 [kg / cm ² ]) made of polyurethane foam is integrally formed on the outer periphery of the above.

The outer circumference of the elastic layer 11 is coated with a conductive and heat-shrinkable tube 12, and the heat-shrinkable tube 12
Since the end of is directly adhered to the shaft 10, conduction is ensured between the heat-shrinkable tube and the shaft even if the elastic layer 11 is made of a non-conductive material, and development is performed by applying a development bias voltage to the shaft. Makes it possible.

The inner diameter of the tube 12 before the heat shrinkage is φ22.
[Mm], after inserting the elastic layer 11 inside the tube 12 before heat shrinking, decompressing the environment, and further 100 [° C.]
Then, the tube 12 is shrunk to cover the outer circumference of the elastic layer 11 to obtain a developer carrying member.

The tube 12 is a conductive and flexible tube in which conductive particles are dispersed in a binder,
More specifically, it is an extruded tube in which 6 [wt%] of carbon black is dispersed in polyurethane resin to have a volume resistivity of 10 ⁴ [Ω · cm], and the outer surface thereof has a surface roughness Rz of 1 [μm]. As described above, the sandblast treatment is performed, the dynamic friction coefficient is 0.5, and the wear amount according to the JIS-K7311 wear test is 100 [mg].

In the present embodiment, printing is performed by changing the hardness of the elastic layer (Asker C hardness) [degree], the film thickness t [cm] of the tube, and the longitudinal elastic modulus E [kg / cm ² ] of the tube. An experiment was conducted to observe image defects and the surface condition of the latent image carrier.

The results of the printing experiment are shown in Table 7.

In Table 7, “◯” in “Evaluation” is 600
The line image of [DPI] is formed without thickening of the line or tailing at the end of the image, and after forming 10,000 images, the filming of the developer is not seen on the tube. This shows that a high-density solid image having an OD value of 1.4 or more can be stably formed without a background fog, and that the developer is not fixed or scratched on the latent image carrier. Also, △ is
A line image of 600 [DPI] could be formed without line thickening or a tail trail at the end of the image.
This shows that the filming of the developer had occurred on the tube after the image formation of one sheet.

[0110]

[Table 7]

In FIG. 7A, since the elastic modulus of the elastic layer 11 is as small as 8 [kg / cm ² ], if the developer is directly conveyed on the surface of the elastic layer, Upstream of the contact position between the latent image carrier 1 and the elastic layer 11 and the elastic blade 13, the ridges of the elastic layer are formed as shown by A and B in FIG. 7B, respectively, and the strain is released. Therefore, the elastic layer 11 or the elastic blade 13 causes periodic vibration (stick slip), which causes a concentration fluctuation. Further, when the elastic layer 11 is made of a material that easily causes compression set, the developer carrying member is compressed by an abutting member such as an elastic blade when the developer carrying body is not in operation to generate permanent set, and the developer carrying amount is changed. I will end up.

Therefore, in this embodiment, the elastic layer 11
By coating the outer periphery of the tube with a tube having an appropriate longitudinal elastic coefficient E and a film thickness t, the developer transportability and chargeability are improved, and the elasticity generated upstream of the portion where the developer carrier is pressure-contacted. Rigidity of the layer is prevented by the rigidity of the tube 12, and since the tube 12 has sufficient flexibility, soft pressure contact with the photoconductor is possible, and a sufficiently wide developing nip can be secured, so high density is achieved. , It became possible to print high resolution images at high speed.

Further, even when the developer carrying member is not in operation, the pressure contact force of the contact member such as the elastic blade can be effectively dispersed by the rigidity of the tube. It has become possible to use it as a layer, and it has become possible to reduce the hardness of the elastic layer and to manufacture the developer carrying member at low cost.

(Comparative Examples 7 to 11) This comparative example is the same as Example 3.
2 to 38, and in the developer carrier shown in FIG. 7, the hardness of the elastic layer (Asker C hardness) [degree],
Tube thickness t [cm], tube longitudinal elastic modulus E
A printing experiment was conducted by changing [kg / cm ² ] to observe image defects and the surface state of the latent image carrier.

The developer carrying member 9 was manufactured with the same material, shape and manufacturing method as in Examples 32 to 38, and mounted on the developing device shown in FIG. 2 to perform a printing experiment.

The results of the printing experiment are shown in Table 8.

[0117] In Table 8, × ⁺ is in the "evaluation", flexible because the stiffness of the tube 12 coated is too high on the outer circumference is decreased in the elastic layer 11, can be sufficiently relieve pressure pressure of the developer carrying member Instead, the developer adheres to the tube 12 and the latent image carrier (filming), and countless scratches are generated on the surface of the latent image carrier. Also ×
^-, despite coating the tube 12 to the outer periphery of the elastic layer 11, upstream of the portion where the developer carrying member is brought into pressure contact,
A part where the surface of the developer carrier is raised is generated,
This shows that the developer bearing member and the elastic blade vibrated periodically, and only an image with density fluctuation and background fog could be formed.

[0118]

[Table 8]

(Embodiment 39) FIG. 8 is an explanatory view of the mechanical characteristics of the developer carrying member used in the developing device in another embodiment of the present invention, and is shown in FIG. 7 (a). 3 shows conditions under which the developer carrier having the structure is mounted on the developing device shown in FIG. 2 to perform printing and prevent stick-slip from occurring.

In FIG. 7 (a), when the hardness of the elastic layer 11 is 30 degrees or less in Asker C type hardness (manufactured by Kobunshi Keiki Co., Ltd.), the elastic layer is easily deformed. 1
1 and latent image carrier 1 or elastic layer 11 and elastic blade 1
The stick-slip phenomenon occurs at the contact portion of No. 3.

Therefore, the applicant of the present invention covers the outer periphery of the elastic layer 11 with a tube 12 having a longitudinal elastic modulus E and a film thickness t satisfying the following expressions, so that the portion where the developer carrying member is pressed is contacted. The rigidity of the tube prevented the bulging of the elastic layer that occurred upstream.

[0122] 5 · r ³ / I ≦ E [kg / cm ^{2] _{I = π × (d 1 4}} -d 2 4) / 64 r = (d 1 + d 2) / 4 [cm] t = (d ₁ -D ₂ ) / 2 [cm] π: circular constant d ₁ : outer diameter of tube [cm] d ₂ : inner diameter of tube [cm] However, if the rigidity of the tube 12 is too large, the flexibility of the tube is lost. Therefore, the longitudinal elastic modulus E of the tube must satisfy the following equation.

E ≦ 40000 · r ³ / I [kg / cm ² ] If the hardness of the elastic layer 11 is large, the tube 1
If the film thickness t of 2 and the longitudinal elastic modulus E are too large, the flexibility is lost. Therefore, when the hardness of the tube is 35 degrees or more by an Asker C type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.), the tube is It is desirable that the longitudinal elastic modulus E of the above satisfies the following equation.

E ≦ 150 · r ³ / I [kg / cm ² ] The film thickness t of the tube 12 may be any value as long as it satisfies the above relational expression, but if it is too thin, handling becomes difficult. , 0.0015 ≤ t [cm] or more is desirable.

The developer carrying member of the present embodiment was used in the developing device shown in FIG. 2 to continuously form 600 [DPI] line images, character images and solid images over 10,000 sheets. Since the outer circumference of the elastic layer is covered with a flexible tube, the pressure contact pressure between the developer bearing member and the latent image bearing member is relieved, and stick slip and compression set of the elastic layer do not occur. It is possible to perform pressure contact development without solidifying the developer or damaging the latent image carrier, and a line image of 600 [DPI] is formed without line thickening or a trailing edge at the edge of the image. Even after the image formation, no fusing such as filming of the developer was observed on the tube, and a solid image of high density with an OD value of 1.4 or more free of background fog was stable for a long period of time. It could be formed.

As the material for the tube 12, resin, rubber, Ni, Cu, and
Metals such as Zn and Al, alloys containing them, etc., that can be formed into thin cylinders can all be used. Preferably, they are processed into the form of heat-shrinkable tubes and the hardness of the elastic layer is adjusted by the gripping force. A heat shrinkable resin or the like that is possible is desirable.

(Embodiment 40) FIG. 9 is a schematic cross-sectional view of a developer carrier used in a developing device in another embodiment of the present invention. The same numbers are given to the members and the description thereof is omitted. In FIG. 9, the developer carrying member 9 is formed by integrally molding an elastic layer 11 made of silicon rubber on the outer circumference of a stainless steel shaft 10. The elastic layer 11 has a skin layer 42 on the outer circumference of a foam layer 41. It has a structure such that it is made conductive with a volume resistivity of about 10 ⁷ [Ω · cm] by dispersing 3 [wt%] of carbon black, and the rubber hardness is 25 with an Asker C type hardness tester.
It is degree.

The outer circumference of the elastic layer 11 is covered with a conductive and heat-shrinkable tube 12.
Is adhered onto the elastic layer 11 with a conductive adhesive, the conduction between the surface of the heat-shrinkable tube and the shaft is secured, and development can be performed by applying a development bias voltage to the shaft.

The inner diameter of the tube 12 before the heat shrinkage is φ24.
[Mm], after inserting the elastic layer 11 inside the tube 12 before heat shrinking, decompressing the environment, and further 120 [° C.]
Then, the tube 12 is shrunk to cover the outer circumference of the elastic layer 11 to obtain a developer carrying member.

The tube 12 is a conductive and flexible tube in which conductive particles are dispersed in a binder,
More specifically, carbon black 6 [wt%] dispersed in polyurethane resin has a volume resistivity of 10 ⁴ [Ω · cm] and a film thickness of 5
It is a tube produced by extrusion molding of 0 [μm].

The magnetic field generating layer 81 is obtained by coating the tube 12 with a magnetic coating in which carbon black and magnetic powder are dispersed in a binder by the roller coating method. 0.5 [mm] or less, preferably 0.1 so as to have flexibility even when raised
(Mm) obtained by the following, Examples of carbon black are suitable good acetylene black conductivity, 10 ⁴
Conductive to [Ω · cm].

Although polyester resin was used as the binder, polyurethane, epoxy resin,
Vinyl acetate, vinyl alcohol, vinyl butyral, vinyl formal, vinyl copolymer resin such as vinyl ethyl ester or polyamide or nitrocellulose or cellulose acetobutyrate or a blend of these with other resins can be used. By blending vinyl, vinyl chloride, and polyurethane, or blending cellulose acetobutyrate and vinyl formal, it is possible to complement each other's characteristics and design a binder that has both dispersibility and mechanical strength.

As the magnetic powder, known magnetic powders as magnetic recording materials and magnet materials can be used, and more specifically, magnetic materials containing at least one element of Fe, Ni, Co, Mn and Cr. , For example, γ-Fe _{2
O 3, Ba-Fe, Ni} -Co, Co-Cr, Mn-A
1 or the like can be used.

The outer surface of the magnetic field generating layer 81 has a surface roughness Rz of 1
Sand blasting is performed to obtain [μm], the dynamic friction coefficient is 0.5, the wear amount according to the JIS-K7311 wear test is 150 [mg], and the magnetic head is used at a pitch of 100 [μm] in the circumferential direction. It is magnetized.

The developer carrying member of the present embodiment was used in the developing device shown in FIG. 2 to continuously form a line image, a character image and a solid image of 600 [DPI] over 10000 sheets. Since the outer circumference of the elastic layer is covered with a flexible tube, the pressure contact pressure between the developer bearing member and the latent image bearing member is relieved, and stick slip and compression set of the elastic layer do not occur. It is possible to perform pressure development without solidifying the developer or damaging the latent image carrier, and a line image of 600 [DPI] is formed without line thickening or a trailing edge at the edge of the image. Even after the image formation, no fusion such as filming of the developer was observed on the tube, and a high density solid image with an OD value of 1.4 or more without background fog was stable for a long period of time. It could be formed.

Further, although silicon rubber, which does not have good adhesion to the magnetic field generating layer, is used as the elastic layer, the surface is covered with a tube (polyurethane resin) of a material that easily adheres to the magnetic field generating layer. The magnetic field generating layer can be arranged on the developer carrier with sufficient adhesion strength, and therefore the magnetic field generating layer is unlikely to peel or crack due to external force such as compressive deformation, so that a developer carrier suitable for pressure contact development can be provided. I was able to get it.

Further, since the magnetic field generating layer 81 is magnetized so that the minimum magnetization reversal pitch is 100 [μm] or less, the leakage magnetic flux attracting the magnetic developer is about several tens from the surface of the magnetic field generating layer. The thickness of the developer was limited to [μm], and at the same time, the developer was uniformly thinned, and at the same time, the variation of the developer carrying amount on the developing roller due to the magnetic brush formation was suppressed, and an image with less uneven density could be stably formed.

(Embodiment 41) FIG. 5A is a schematic sectional view of a developer carrying member used in a developing device in another embodiment of the present invention. Members having the same function will be denoted by the same reference numerals and description thereof will be omitted. Figure 5 (a)
In the developer carrying member 9, an elastic layer 11 made of foamed silicon rubber is integrally formed on the outer circumference of a stainless steel shaft 10. The elastic layer 11 has a skin layer 42 on the outer circumference of the foam layer 41. Carbon black 3 [wt
%], It is made conductive with a volume resistivity of about 10 ⁷ [Ω · cm], and the rubber hardness is 27 degrees by an Asker C type hardness meter.

The outer circumference of the elastic layer 11 is covered with a conductive and heat-shrinkable tube 12 in which magnetic powder is dispersed, and the tube 12 is coated with a conductive adhesive.
Since it is adhered on the top surface, conduction is secured between the tube surface and the shaft, and development can be performed by applying a development bias voltage to the shaft.

The inner diameter of the tube 12 before heat shrinkage is φ22.
[Mm] and after inserting the elastic layer 11 into the tube 12 before heat shrinking, the environment is decompressed and further heated to 90 [° C.] to shrink the tube 12 and coat the outer circumference of the elastic layer 11. To obtain a developer carrier. The tube 12 is a conductive and flexible tube in which conductive particles are dispersed in a binder, and more specifically, a volume resistivity 10 in which carbon black 6% by weight is dispersed in polyurethane resin.
A tube made by extrusion molding with a film thickness of ⁴ [Ω · cm] and a film thickness of 50 [μm].

The tube 12 is a heat-shrinkable tube in which carbon black and magnetic powder are dispersed in a binder, and its film thickness can be increased even if the content of magnetic powder increases and the hardness of the tube increases. 0.5 [mm] to have flexibility
The carbon black is preferably 0.1 mm or less, and acetylene black having good conductivity is suitable as the carbon black.

Polyurethane resin was used as the binder, but in addition to this, EPDM, polyvinyl chloride, fluororesin, fluororubber, silicone rubber, polyethylene,
Materials having heat shrinkability such as polypropylene, linear polyester, polyamide resin, crystalline polyolefin, crosslinked polyolefin, non-crosslinked polyolefin, crystalline polyolefin copolymer and PET can be used.

As the magnetic powder, known magnetic powders for magnetic recording materials and magnet materials can be used. More specifically, a magnetic material containing at least one element of Fe, Ni, Co, Mn and Cr. , For example, γ-Fe _{2
O 3, Ba-Fe, Ni} -Co, Co-Cr, Mn-A
1 or the like can be used.

The outer surface of the tube 12 has a surface roughness Rz of 1
Sandblasting has been performed so as to be [μm], the dynamic friction coefficient is 0.45, the wear amount according to the JIS-K7311 wear test is 160 [mg], and the magnetic head is used at a pitch of 100 [μm] in the circumferential direction. It is magnetized.

The developer carrying member of the present embodiment was used in the developing device shown in FIG. 2 to continuously form a line image, a character image and a solid image of 600 [DPI] over 10,000 sheets. Since the outer circumference of the elastic layer is covered with a flexible tube, the pressure contact pressure between the developer bearing member and the latent image bearing member is relieved, and stick slips and compression set of the elastic layer do not occur. It is possible to perform pressure development without solidifying the developer or damaging the latent image carrier, and a line image of 600 [DPI] is formed without line thickening or a trailing edge at the edge of the image. Even after the image formation, no fusion such as filming of the developer was observed on the tube, and a high density solid image with an OD value of 1.4 or more without background fog was stable for a long period of time. It could be formed.

Further, although the elastic layer was formed of a foam which was difficult to apply the magnetic paint, the elastic layer was covered with the heat-shrinkable tube in which the magnetic powder was dispersed. It is possible to easily dispose the generating layer, and the magnetic field generating layer (tube in which magnetic powder is dispersed) does not cause peeling or cracking due to external force such as compressive deformation, and to obtain a developer carrier suitable for pressure development. I was able to do it.

Further, since the tube 12 is magnetized so that the minimum magnetization reversal pitch is 100 [μm] or less, the leakage flux attracting the magnetic developer is about several tens [μm] from the surface of the magnetic field generating layer. It was possible to suppress the variation in the amount of developer conveyed on the developing roller due to the formation of the magnetic brush to a fine pitch and to stably form an image with little density unevenness.

1 to 9, the present invention is not limited to the configurations shown in the drawings. In particular, the structure of the tube 12 is not limited to those shown in FIGS. 1, 4, 5, 7, and 9, and it is possible to add an additive such as a dispersant to the binder of the tube, or to add a functional powder other than carbon black such as conductive powder. It is also possible to disperse particles and use them as floating electrodes to improve the developing electrode effect. By disposing a functional layer, such as an adhesive layer or a resistance layer, on the outer or inner surface of the tube, the adhesion and conductivity of the tube can be improved. It is also possible to improve abrasion resistance, prevention of bias leak, improvement of developer transport characteristics, and development electrode effect. Further, it is possible to make a fine hole on the surface of the tube or form a mesh.

Further, the arrows indicate the rotating directions of the respective members, but the present invention is not limited thereto.

Further, the developing method can be used regardless of whether it is regular development or reversal development.

The developer used in the present invention may be a magnetic developer or a non-magnetic developer regardless of whether it is a one-component type developer, a two-component type developer or a 1.5-component type developer. As the component-based developer, all known developers can be used, and either a resin-based developer or a wax-based developer may be used. As is well known, the composition of the developer is a resin to which magnetic powder, a coloring agent, an external additive and other additives are added, and is prepared by a pulverization method, a polymerization method or the like.

Although the embodiments have been described above, the present invention can be widely applied not only to the above embodiments but also to a developing device for electrophotography and the like, and is particularly effective when applied to a printer, a copying machine, a facsimile and a display. Is.

[0153]

As described above, the developer carrying member has a structure in which the elastic layer and the tube are concentrically arranged on the outer periphery of the shaft, and the surface roughness Rz of the tube is 0.1 to 10.
By setting the [μm] and the coefficient of dynamic friction to 0.2 to 0.7, the developer transport amount and the charge amount can be suitably maintained for development and stably maintained for a long period.

Further, the wear resistance of the tube is determined by JIS-K
When the amount is 700 mg or less in the 7311 abrasion test, the surface of the developer bearing member is not significantly worn by rubbing with the developer, and fluctuations in surface roughness and friction coefficient can be suppressed, so that the developer bearing member can be used for a long period of time. As a result, the developer conveyance amount and the charge amount are stabilized.

Further, even if the elastic layer is made of a material having a low hardness, such as foamed rubber, the surface of the tube is covered with a tube having an appropriate rigidity, so that the surface can be polished or roughened, and the outer diameter can be reduced. In addition to easy control of runout and surface roughness, even when a functional layer such as a magnetic field generating layer is provided on the outer periphery of the elastic layer, there is a wide selection of materials that can be used as a tube. It is possible to facilitate the disposition of the functional layer, for example, by improving the adhesion with the magnetic paint by using the same type of material.

Furthermore, since the surface roughness of the tube can be processed by the tube alone, accurate processing can be easily performed without being affected by the elastic layer.

Furthermore, the longitudinal elastic modulus E of the tube [kg /
cm ² ] and the film thickness t [cm] of the tube satisfy the formula: E × t ≦ 12000, the rigidity of the tube can be improved within the range of sufficient flexibility, and fatigue due to repeated stress Since it does not break, the surface condition of the tube can be easily processed and controlled, and the surface of the developer carrier can be used as a developer carrier for pressure development in which the surface is constantly exposed to deformation. Further, since the tube can be provided with sufficient flexibility, if the elastic layer is made to have a low hardness, soft contact with the latent image bearing member becomes possible, and the contact width between the elastic blade and the latent image bearing member is increased. Since it can be widely used, the charge amount of the developer can be improved and high-speed printing can be performed.

Further, by imparting appropriate rigidity to the tube, even if the hardness of the elastic layer is very low, the contact pressure with the elastic blade or the photosensitive member can be effectively dispersed by the rigidity of the tube, so that the local It is possible to prevent periodic micro-vibration (stick-slip) that occurs when releasing the compressive deformation that has occurred, and partial compression set of the elastic layer.

Further, even when a functional layer such as a magnetic field generating layer is provided on the surface of the tube, the tube is not locally largely deformed, so that the functional layer is unlikely to peel or crack due to compressive deformation or the like. Therefore, the mechanical properties such as adhesion and flexibility of the functional layer can be improved.

Furthermore, even if a foam is used as the elastic layer, the outer circumference of the elastic layer is covered with the tube, so that the opening of the cell exposed on the surface of the elastic layer can be closed.
Without clogging of the developer on the surface of the developer carrier,
An image with less background fog can be formed. Also,
Even when applying a magnetic coating or the like to the surface of the developer carrier, the surface can be made smooth, so that a functional layer such as a magnetic field generation layer can be easily provided even on a foam that is difficult to apply. it can.

Further, if a functional powder such as magnetic powder is dispersed in the tube covering the outer periphery of the elastic layer to form a functional layer, even if the elastic layer is made of a material such as silicon rubber that is difficult to adhere to. The functional layer can be easily provided, and the functional layer is less likely to peel off when pressure development is performed, and the production can be easily performed.

Further, by covering the outer circumference of the elastic layer with a tube, it is possible to prevent the plasticizer and the like contained in the elastic layer from seeping out, and it is possible to prevent the developer from clogging into the elastic layer. A developer carrier having a long life and little deterioration of the developer and the developer can be obtained.

Therefore, according to the present invention, there is an excellent effect that it is possible to provide at low cost a developing device which has few image defects such as background fog and tailing, and which can stably obtain a high-resolution image for a long period of time. It is a thing.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a developer carrier used in a developing device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the developing device of the present invention.

FIG. 3 is an explanatory view showing developing characteristics of the developing device of the present invention.

FIG. 4 is a cross-sectional outline view and a mechanical characteristic explanatory view of a developer carrying member used in a developing device in another embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a developer carrying member used in a developing device according to another embodiment of the present invention.

FIG. 6 is an explanatory view of mechanical characteristics of a tube which constitutes a developer carrier used in the developing device in this comparative example.

FIG. 7 is a schematic cross-sectional view of a developer carrier used in a developing device according to another embodiment of the present invention.

FIG. 8 is an explanatory view of mechanical characteristics of a developer carrying member used in a developing device according to another embodiment of the invention.

FIG. 9 is a schematic cross-sectional view of a developer carrying member used in a developing device according to another embodiment of the present invention.

[Explanation of symbols]

 1 ···· Latent image carrier 7 ··· Development device 8 ···・ ・ ・ ・ ・ ・ ・ ・ Developer 9 ・ ・ ・ ・ ・ ・ ・ ・ Developer carrier 10 ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ Shaft 11 ・ ・ ・ Elastic layer 12 ・ ・ ・ Tube 13 ・ ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ Elastic blade 17 ・ ・ ・ Peeling supply roller 21 ・ ・ ・ ・ ・ Binder 22 ・ ・ ・ Carbon black 41 ・ ・ ・ Foam layer 42 ・ ・ ・ ・ ・ ・... Skin layer 81 ... Magnet Generating layer

Claims (5)

[Claims] 1. A developing device for holding a thin developer layer formed on a developer carrier and transporting the developer layer to a position facing the latent image carrier, wherein the developer carrier is the outer periphery of a shaft. Has a structure in which an elastic layer and a tube are concentrically arranged, and the surface roughness Rz of the tube is 0.1 to 10 [μ
m] is a developing device. 2. The developing device according to claim 1, wherein a coefficient of dynamic friction between the outer surface of the tube and the developer layer is 0.2 to 0.7. 3. A developing device for holding a thin developer layer formed on a developer carrier and transporting the developer layer to a position facing the latent image carrier, wherein the developer carrier is the outer periphery of a shaft. In the developing device, the elastic layer and the tube are concentrically arranged, and the abrasion resistance of the tube is 700 [mg] or less in the JIS-K7311 abrasion test. 4. A developing device for holding a thin developer layer formed on a developer carrier and transporting the developer layer to a position facing the latent image carrier, wherein the developer carrier is the outer periphery of a shaft. Has a structure in which an elastic layer and a tube are concentrically arranged, and the longitudinal elastic modulus E [kg / cm ² ] and the film thickness t [cm] of the tube satisfy the formula: E × t ≦ 12000 A developing device. 5. A developing device, which holds a thin developer layer formed on a developer carrier and conveys the developer layer to a position facing the latent image carrier, wherein the developer carrier is the outer periphery of a shaft. Has a structure in which an elastic layer and a tube are concentrically arranged, and the longitudinal elastic modulus E of the tube is expressed by the formula: 5 × r ³ / I ≦ E ≦ 40000 × r ³ / I
[Kg / cm ^{2] _{I = π × (d 1 4}} -d 2 4) / 64 r = (d 1 + d 2) / 4 π: circle ratio d _1: the outside diameter of the tube (cm) d _2: Tube The developing device is characterized by satisfying the inner diameter [cm] of