JP2001281983A - Developer carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer carrier with out causing any crazing or cracking in a coating layer. SOLUTION: After paint is applied by a roll coating method, it is half-dried, and further the developer carrier 9 is rotated while it is press-contacted by a leveling member 61, so that the local unevenness of film thickness is leveled on the developer carrier 9 having the coating layer 12. Surface fogging and irregular density caused by the unevenness of the film thickness of the coating layer 12 are reduced, and the life of the developer carrier 9 is prolonged and the production cost thereof is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer carrier used in an electrophotographic developing device and a method for producing the same.

[0002]

2. Description of the Related Art A conventional developer carrier has a mag roll rotatably disposed in a non-magnetic cylindrical rotatable sleeve, as is known as a one-component magnetic brush developing method. The magnetic toner conveys and develops the magnetic toner. However, in the conventional one-component magnetic brush developing method using the developer carrier, the magroll hinders the weight reduction and the cost reduction of the developer carrier.

In order to improve the above-mentioned one-component magnetic brush developing method, Japanese Patent Application No. 2-58321 and the like use a developer carrier having at least a magnetic field generating layer and use a magnetic developer to achieve high image quality. A developing device capable of forming an image has been proposed.

In the method for manufacturing a developer carrier used in the above-described developing apparatus, the magnetic field generating layer (coating layer)
The application of a magnetic paint by a roll coating method has been studied as a means for forming a coating.

In the rolling method, a coating material having a wide range of viscosities can be uniformly applied, and a smooth coating film can be formed.

[0006] The magnetic coating material dispersed in the magnetic coating material has a magnetic moment and therefore has extremely poor dispersibility.
In order to ensure dispersion stability, the magnetic paint needs to have an extremely higher viscosity than ordinary paints. In addition, in a coating film formed by applying a magnetic paint, a smaller void due to evaporation of the solvent provides better magnetic properties. Is preferable, and as a result, the magnetic paint tends to have a higher viscosity.

In order to improve the one-component magnetic brush developing device, as disclosed in Japanese Patent Application Laid-Open No. 2-311871, a one-component non-magnetic developer provided with a triboelectric charge is directly carried on the surface of a rubber roll and transported. Developer carriers have been proposed.

In the above-described developer carrier, a plasticizer is added to a rubber roll in order to realize soft pressure contact with the latent image carrier. However, when the plasticizer in the developer carrier is used, Bleed-out causes damage to the latent image carrier and the like. To prevent this, a bleed-out prevention layer is provided on the surface of the rubber roll by coating or the like.

When a functional layer (coating layer) such as a bleed-out prevention layer is provided, a coating method such as a dipping method is generally used. , Abrasion resistance, and the like, and the materials added to the paint are also diverse such as carbon black and metal powder. As a result, the viscosity of the paint tends to increase.
As described above, the dipping method is simple as a method of forming a coating film on the surface of the developer carrying member. However, as a means for applying a high-viscosity paint to the surface of the developer carrying member smoothly, a roll coating method is used. Is attracting attention.

[0010]

However, when the above-mentioned magnetic field generating layer and the like are formed by coating by a roll coating method, when the developer carrier is separated from the coating roll, the thickness of the magnetic coating film is reduced. When the press-contact development is performed using this developer carrier, the developer is clogged in a place where the thickness variation of the magnetic coating film is large, causing the background fog. Or
There has been a problem that image density unevenness occurs due to pressure contact pressure fluctuation caused by film thickness unevenness.

In a portion where the thickness unevenness of the coating film is large,
There has been a problem that a crack is generated in the magnetic field generating layer due to internal stress or drying unevenness of the coating film, and that a variation in magnetic characteristics due to a difference in film thickness causes nonuniform development amount.

Further, when the magnetic field generating layer is applied by a dipping method and disposed, the magnetic paint has a very high viscosity, so that streaks of the magnetic paint are generated on the surface of the developer carrier in a streak shape. In addition, there is a problem that image density unevenness is caused.

Further, in the case where the magnetic paint is applied to the base roller having a rough surface, the surface state of the roller after coating reflects the surface state of the base roller.
It is necessary to perform coating after polishing the surface of the base roller in advance, or to grind the roller surface after coating, which has a problem that the number of manufacturing steps increases and the manufacturing cost increases.

Therefore, the present invention solves such a problem, and an object of the present invention is to change the layer thickness of the developer formed on the developer carrier by changing the position on the developer carrier. It is an object of the present invention to provide a developer carrying member capable of forming an image with a constant density and no unevenness in density.

Another object of the present invention is to provide a developer carrier which does not cause cracks or cracks in a coating layer.

[0016]

According to the present invention, there is provided a developer carrier having a multi-layer structure for holding and transporting a developer to a position facing a latent image carrier. Is to form a coating layer by applying a coating material at least by a roll coating method, and the film thickness variation rate V of at least the seam portion of the coating layer is represented by the following formula: V <35 [%] V = (R × 100) / T [%] R = tmax-tmin [μm] R: maximum film thickness difference [μm] t: average film thickness [μm] tmax: maximum film thickness [μm] tmin: minimum film thickness [μm] It is characterized by.

Further, the present invention is characterized in that the coating layer is coated with a coating material by a roll coating method and then subjected to a leveling treatment. Further, the present invention is characterized in that the coating layer is formed by applying a magnetic paint.

[0018]

According to the above construction of the present invention, since no seam is formed in the coating layer constituting the developer carrier, the thickness of the coating layer becomes constant over the entire circumference of the developer carrier, Therefore, clogging of the developer on the developer carrier due to a variation in the thickness of the coating layer and fluctuation of the pressure contact pressure with the latent image carrier are eliminated,
An image can be formed without background fog and density unevenness.

Further, since the thickness of the coating layer is made constant during coating, cracks and the like due to internal stress and drying unevenness of the coating at the time of coating drying do not occur. The yield of the developer carrier is improved, the durability against repeated stress during use is improved, and the life of the developer carrier is extended.

Further, when the coating layer is formed of a magnetic paint, by keeping the thickness of the coating film constant, the variation in the magnetic characteristics due to the magnetic film thickness and the touch due to the head touch of the magnetized head are reduced. Magnetization unevenness can be suppressed.

Further, according to the above configuration of the present invention, the coating layer is formed on the base roller by using a simple coating method such as a dipping method or a roll coating method without generating a seam. The agent carrier can be easily manufactured at low cost. Hereinafter, the present invention will be described in detail with reference to examples.

[0022]

(Embodiment 1) FIG. 1 is a schematic cross-sectional view of a developer carrier according to an embodiment of the present invention, in which a conductive elastic layer 11 is coated on the outer periphery of a conductive shaft 10. The processing layer 12 is provided concentrically. The coating layer 12 is formed by applying a magnetic paint in which conductive carbon black 22 and magnetic powder 23 are dispersed in a binder 21 by a roll coating method. The thickness of the coating layer 12 is 500 [μm] or less, preferably 100 [μm] or less so that the coating layer 12 has sufficient flexibility even if the hardness increases due to the dispersion. Because of the flexibility, even if development is performed in a state where the developer carrier 9 is pressed against a latent image carrier (not shown), the pressing pressure is effectively relieved by the elastic layer 11 and soft contact is achieved. This makes it possible to form an image without damaging the surface of the latent image carrier or solidifying the developer.

The average thickness t of the developer carrier is 100 μm
m], the maximum film thickness difference R is 35 [μm], and therefore the film thickness variation rate V is 35 [%].

When the developer carrying member 9 was used in the developing apparatus shown in FIG. 2 to form an image, the film thickness unevenness was small over the entire coating layer. Therefore, stress concentration does not occur locally in the coating layer, and therefore, the coating film does not crack even after long-term use.

Further, since the thickness of the coating layer is constant, the magnetic characteristics are uniform regardless of the position on the developer carrying member, and the image density non-uniformity due to the variation of the magnetic binding force does not occur. There was almost no change in the pressure between the developer carrier and the latent image carrier, and a high-resolution image without density unevenness could be formed.

Furthermore, no sharp change in the film thickness such as a seam was eliminated on the surface of the coating layer, and the phenomenon that the developer was clogged at a place where the film thickness of the coating film was large and the ground fogging did not occur.

In FIG. 2, the latent image carrier 1 is formed by coating a photosensitive layer 3 having organic or inorganic photoconductivity on a conductive support portion 2. 3 is charged using a charger 4 such as a corona charger or a charging roller, and then light emitted from a light source 5 such as a laser or LED is selectively transmitted to the photosensitive layer 3 through an imaging optical system 6 according to an image. Irradiation is performed to obtain a potential contrast to form an electrostatic latent image. On the other hand, the developing device 7 conveys and develops the developer 8, and holds the developer 8 on the developer carrier 9 by a magnetic force generated from a coating layer 12 made of a magnetic paint, and the non-magnetic or After adjusting the amount of charge with an elastic blade 13 in the form of a leaf spring made of a magnetic metal or resin and thinning to an appropriate amount,
The developer carrier 9 is rotated to transport the developer thin layer. When the developer 8 on the developer carrier 9 is transported to the pressure contact portion between the developer carrier 9 and the latent image carrier 1, the potential contrast of the latent image carrier 1 and the developing bias applying means 1
The electrostatic latent image is adhered to the latent image carrier 1 according to the developing electric field formed by the developing device 4 and the electrostatic latent image is visualized. Further, an image of the developer is transferred onto the recording paper 16 using a transfer device 15 such as a corona transfer device or a transfer roller, and the developer is fixed on the recording paper using heat or pressure, and a desired image is formed on the recording paper. What you get.

Here, the coating layer 12 has a viscosity of 9000 [cp]
s], and BaO-6Fe ₂ O ₃ fine powder having a coercive force of 3000 [Oe] and a residual magnetization of 1000 [Gauss] is used as a magnetic powder constituting the magnetic paint. 100% in the circumferential direction of the developer carrier with the head
[Μm] pitch in-plane magnetization. As the magnetic powder, not only BaO-6Fe ₂ O ₃ but also a magnetic powder known as a magnetic recording material or a magnet material can be used. More specifically, at least one of Fe, Ni, Co, Mn, and Cr is used. Magnetic material containing the element of, for example, γ
_{-Fe 2 O 3, Co-γ} -Fe 2 O 3, Ba-Fe, Ni-
Co, Co-Cr, Mn-Al or the like can be used, and the shape is not limited to acicular or granular, and can be used. In this embodiment, the leakage magnetic flux density on the surface of the developer carrying member is 200 [Gauss], but is 50 [Gauss].
s] If the leakage magnetic flux density is equal to or higher than that, the developer has a sufficient developer transporting property without lowering the density even when a solid black image is formed. However, in this example, the volume average particle size was 8 [μ
m], and a polyester-based developer having a magnetic powder content of 30 [wt%] was used.

Further, the magnetic field generating layer (coating layer) exhibits good transport performance when the content of the magnetic powder in the developer is between 5 and 65 [wt%]. In the range
The charge amount of the developer (after development) is 10 to 30 [μC / g]
Therefore, it is suitable for forming a high-resolution image because a sufficient image density can be obtained even with a small amount of development due to the coloring effect of the magnetic powder.

(Comparative Example 1) FIG. 3 is a schematic cross-sectional view of a developer carrier of the present comparative example, in which the outer periphery of a shaft 10 and an elastic layer 11 arranged concentrically has a viscosity of 10,000 [c].
ps] is applied by a roll coating method to form a coating layer 12 having a film thickness of 150 μm and a film thickness variation rate V = 50%. The coating layer 12 is formed with a uniform film thickness along the outer periphery of the elastic layer 11,
Very large thickness unevenness occurs in one place. this is,
When the developer carrier 9 is separated from the coating roll (not shown) at the time of coating, the coating layer 12 (coating film) in a portion that has been in contact with the coating roll to the end has a thickness variation (seam). Things.

When this developer carrier 9 was used in the developing device shown in FIG. 2 to form an image having a halftone dot pattern, density unevenness corresponding to the seam of the coating layer was generated. Image formation could not be performed. When the density unevenness at this time is observed in more detail, in a portion where the thickness of the coating layer 12 is particularly large, a sufficient amount of the developer cannot be held on the developer carrier, and a low density image is obtained. Also,
The thin portion adjacent to the thick portion of the coating layer 12 is not sufficiently contacted with the magnetizing head at the time of magnetization and is in an insufficiently magnetized state. However, since the magnetic force was not high enough and the developer was easily clogged, the image was extremely fogged.

When image formation was continued using this developer carrying member, a stress was repeatedly applied to the joint portion of the coating layer at the time when about 1000 A4 size papers were generated, and cracks were generated. Oops.

(Embodiments 2 to 4) In this embodiment, a plurality of developer carriers having different thickness variation rates V of the coating layer 12 in FIG. 3 are used in the developing device shown in FIG. Then, an image was formed, and the image quality such as density unevenness and the durability of the developer carrying member were evaluated. Table 1 shows the results of the film thickness variation rate V, image quality, and durability printing.

As a result, the film thickness variation rate V of the coating layer 12 is 2
When the content is 0% or less, not only is there no clogging of the developer at the joint portion of the coating layer, but also the thickness of the magnetic coating film and the head touch of the magnetizing head can be made uniform. The conveyance amount, the magnetic binding force, and the pressure contact force with the latent image carrier are extremely stable, and it is particularly desirable to perform high-resolution image formation without density unevenness.

The variation rate V of the film thickness of the coating layer 12 is 10
[%] Or less, it is possible to form a good image without density unevenness, and even if the press-contact development in which a stress is repeatedly applied to the coating layer is performed over 25,000 sheets of A4 size paper, Since there is no portion where the thickness of the film rapidly changes, no crack is generated in the coating film. Therefore, it is particularly desirable to keep forming a high-resolution image for a long period of time.

[0036]

[Table 1]

(Comparative Examples 2 to 8) In this comparative example, a plurality of developer carrying members having different thickness variation rates V of the coating layer 12 in FIG. 3 are used in the developing device shown in FIG. Then, an image was formed, and the image quality such as density unevenness and the durability of the developer carrying member were evaluated. Table 2 shows the results of the film thickness variation rate V, image quality, and durability printing.

As a result, the film thickness variation rate V of the coating layer 12 was 3
When it is 5% or less, the fluctuation of the pressure between the developer carrier and the latent image carrier is small, and the fluctuation of the magnetic flux leaking from the coating layer is uniform, so that the transport amount of the developer is stable. As a result, a good image without density unevenness could be formed.

However, when the film thickness variation rate V was 35% or more, only an image having density unevenness and background fog corresponding to the seam of the coating layer 12 could be formed.

When the film thickness variation rate V is 50% or more, the pressure contact stress concentrates on a portion where the film thickness variation of the coating layer is particularly remarkable, causing fatigue failure during continuous printing. Was.

In the image quality shown in Table 2, ○ indicates that an image with sufficient resolution was obtained without background fog and density unevenness, and Δ indicates an image with some background fog and density unevenness. And x indicate that good printing cannot be performed due to uneven density and background fog. In Table 2, in the endurance, ○ indicates that continuous printing was possible without problems over 10,000 sheets of A4 size paper, and △ indicates that continuous printing was possible without problems up to 5000 sheets, but printing was continued. As a result, it was shown that stress concentration occurred in the coating layer and the coating film was broken, and x indicates that the coating film was broken when several hundred sheets were printed.

[0042]

[Table 2]

(Embodiment 5) FIG. 4 is a schematic sectional view of a developer carrier according to another embodiment of the present invention.

FIG. 4A illustrates the structure of the developer carrying member of the present invention. The developer carrying member has a peripheral length slightly longer than the driving roller 25 outside the driving roller 25 including the shaft 10 and the elastic layer 11. A developer carrier 27 comprising a thin cylinder 26 made of Ni, a conductive resin or the like, and a coating layer 12 formed by applying a magnetic paint by a roll coating method on the surface thereof is provided. In addition, the surplus peripheral portion of the developer carrier 27 is brought into contact with the latent image carrier 1 to perform pressure contact development.

FIG. 4B shows the film thickness variation rate V of the coating layer 12 constituting the developer carrier 27 shown in FIG.
This graph shows the relationship between the fluctuation rate Vg of the leakage magnetic flux density from the coating layer 12 which is vertically magnetized at a pitch of 100 [μm].

Here, the variation rate Vg of the leakage magnetic flux density is as follows: when the average leakage flux density is G and the maximum leakage flux density difference is Rg, Vg = (Rg × 100) / G [%] Rg = G _max − G [Gauss] G _max : maximum leakage magnetic flux density [Gauss] G _min : minimum leakage magnetic flux density [Gauss]

In the present embodiment, the relationship between the variation rate Vg of the leakage magnetic flux density and the image quality at that time was examined by changing the variation rate V of the film thickness of the coating layer composed of the magnetic paint. Table 3 shows the results.

As the film thickness fluctuation rate V of the coating layer becomes larger, the fluctuation rate Vg of the leakage magnetic flux density becomes larger, and the density unevenness of the formed image also becomes larger. This is because, in a portion where the coating layer is particularly thick, a strong magnetic binding force acts on the developer, so that the image density is slightly reduced. In a portion where the coating layer is particularly thin, the magnetic binding force is small. , The supply capacity of the developer was not sufficient. Therefore, when a solid image was continuously formed, the supply of the developer could not be performed in time, resulting in an image with insufficient density.

As described above, in the configuration in which the magnetic field generating layer is formed by coating and the magnetic developer is conveyed by the magnetic force, the variation rate V of the thickness of the coating layer is set to 35% or less. If
An image can be formed without density unevenness, and a long-life developer carrier can be obtained.

In the density unevenness in Table 3, ○ indicates that when a solid black image is continuously formed on 20 sheets, the upper and lower ends of the first sheet and the upper and lower ends of the 20th sheet are determined. It shows that the image density difference of the four points was within 0.2 of the OD value,
Indicates that the difference in image density was 0.3 to 0.5 in OD value, and x indicates that the difference was 0.5 or more. However, the image density at this time is such that the OD value at the upper end of the first sheet is 1.45.
Met.

[0051]

[Table 3]

(Embodiment 6) FIG. 5 is an explanatory view of a method of manufacturing a developer carrying member in a conventional embodiment, and shows a one-roller coater 50 by a general reverse coating method. It comprises a roll 51, a doctor blade 52, and a paint pan 53. The coating of the magnetic paint on the developer carrier is performed by using a coating roll 5
With respect to the magnetic paint 54 on the coating roll, which is pumped up from the paint pan 53 according to the rotation of 1 and is regulated to an appropriate amount by the doctor blade 52, the developer carrier 55 before forming the magnetic layer, which is an object to be coated, is coated on the coating roll The magnetic paint on the coating roll is transferred to the object 55 to be coated while rotating in the same direction. Further, the application of the paint is completed by separating the object 55 from the coating roll. At this time, in a state where the object to be coated is being separated from the coating roll, a thin coating film 56 is formed in a portion where the object to be coated and the coating roll are opposed to and in contact with each other because the inflow of the magnetic paint is restricted by the pressing force. In a portion adjacent thereto, the pool of paint generated before and after the opposing portion is transferred to the object to be coated as it is to form a thick coating film 57, so that a very large unevenness in film thickness locally occurs, and If the coating layer was dried and solidified as it was, cracks would occur in the coating layer due to internal stress and uneven drying of the coating film, and the yield would be reduced. In addition, the surface of the coating layer has a large number of bridging patterns in the circumferential direction. In order to use this developer carrier, the surface is polished to remove film thickness unevenness and bridging. In addition, the surface must be subjected to sandblasting or the like to obtain a surface state suitable for development, and the developer carrier is expensive. FIG. 6 is an explanatory diagram of a method of manufacturing a developer carrier according to an embodiment of the present invention. Post-processing is performed on the developer carrier having a coating layer formed by a roll coating method or the like shown in FIG. More specifically, even if a coating layer is formed using a simple coating method such as a conventional roll coating method or dipping method, there is no unevenness in film thickness, and a surface state suitable for development can be easily obtained. It is obtained.

In FIG. 6, the coating layer 12 constituting the developer carrier 9 is formed by a roll coating method, and the surface of the coating layer is formed in a state where the thickness of the coating layer is uneven. It is semi-dried while rotating until it loses its tackiness. Here, the coating layer 12 is a BaO-6Fe ₂ O ₃ magnetic powder and carbon black to a magnetic coating material dispersed in a binder resin, For application, the ratio of magnetic coating and the diluting solvent and the curing agent 20: Mix and disperse at a ratio of 4: 1 to about 10
The coating was performed at a thickness of 0 [μm], and the drying time required for the surface of the coating layer to lose its tackiness was about 1 minute.

Next, a developer carrying member having a diameter of 20 [mm] in a state where the surface of the coating layer has lost the tackiness, has a diameter of 50 [mm].
[Mm] leveling member 61 made of stainless steel,
The contact is made by the urging means 62 at a pressure of 200 g.
At this time, the leveling member 61 is configured to be rotatable with the rotation of the developer carrier 9.

Further, if the developer carrier is rotated with the leveling member in contact with the developer carrier, the coating layer is leveled by the pressing force of the leveling member. Since the thick portion of the coating film receives a particularly high pressing pressure, the semi-solidified paint present in this portion moves to the thin portion of the coating film adjacent to the thick portion of the coating film, and the developer carrier is reduced in number. During the rotation, the thickness unevenness of the coating layer is eliminated.

At this time, since the surface state of the coating layer 12 can be formed into a shape corresponding to the surface state of the leveling member 61, the surface roughness of the leveling member 61 is controlled to control the surface state of the coating layer. It is possible to make the developer carrier suitable for development, and it is not necessary to apply a surface treatment such as polishing or sandblasting to the developer carrier after coating, so that a developer carrier having good surface accuracy can be easily manufactured at low cost. It became possible to manufacture in. In this embodiment, the surface roughness Rz of the leveling member 61 is set to 0.7 [μ].
m] to obtain a developer carrier having substantially the same surface roughness.

The scraper 63 and the cleaning pad 64 which are in contact with the leveling member 61 are for removing the undried paint when transferred to the leveling member. It is impregnated to impart lubricity and releasability to the surface of the leveling member to maintain the same surface state as the initial state for a long time.

In a conventional method of forming a coating film such as a dipping method or a roll coating method, the surface state of the coating layer cannot be controlled, so that it is impossible to apply a thick film in which the coating material easily drips. According to the method for producing a developer carrier of the present invention, the surface state of the coating film can be easily controlled, so that a thick coating film can be formed by a simple method such as a dipping method. In this case, the film thickness is 10 to 300 [μm]
Could be formed.

In this embodiment, a stainless steel roll is used as the leveling member. However, the present invention is not limited to this, and a metal roll such as aluminum or nickel, or a silicon roll such as silicon or fluorine may be used. Any material that can press the coating layer, such as a roll of good release rubber or resin agent, or a multi-layer configuration in which a material with good release such as fluororesin is coated on the outer periphery of the metal shaft Any form may be used. Further, as the driving method of the leveling member, in addition to the method of following rotation with respect to the developer carrier, a driving unit is provided on the leveling member, and the peripheral speed difference is provided to the developer carrier. It is also possible to press with.

The urging force of the leveling member against the developer carrier varies depending on the viscosity of the coating material, the half-drying time, etc., but good results are obtained in the range of about 0.2 to 4 kg. Further, even if the leveling process is performed in a state where the distance between the leveling member and the developer carrying member is kept constant (substantially the thickness of the coating layer) instead of the urging means 62, a good coating layer can be formed. A surface condition was obtained.

Further, the half-drying time until the surface of the coating layer loses the tackiness can be reduced by drying in a high-temperature atmosphere (for example, a 90 ° C. atmosphere).

In this embodiment, a polyester resin is used as a binder for forming a coating layer. In addition, a polyurethane resin such as polyurethane, epoxy resin, vinyl acetate, vinyl alcohol, vinyl butyral, vinyl formal and vinyl ethyl ester is used. Polymerized resins or polyamides or nitrocellulose or cellulose acetobutyrate or those blended with other resins can be used.For example, vinyl acetate and vinyl chloride and polyurethane are blended, or cellulose acetobutyrate and vinyl formal are used. It is possible to design a binder that complements each other's properties by blending, etc., and achieves both dispersibility and mechanical strength.

(Embodiment 7) FIG. 7 is an explanatory view of a method of manufacturing a developer carrying member according to another embodiment of the present invention. In order to reduce the semi-drying time and prevent the semi-dry paint from transferring to the leveling member,
It is an improvement.

Referring to FIG. 7, a developer carrier 9 is obtained by applying a magnetic coating material to a base roller 70 made of a rigid or elastic material with a roller coater. It has unevenness.

Next, the developer carrying member having the film thickness unevenness and the leveling member 61 are held such that the distance between the opposing portions becomes a predetermined value. At this time, the leveling member 61
Since the surface is covered with the lubricant 72 discharged from the nozzle 71, the portion where the developer carrier 9 and the leveling member 61 face each other is pressed with the lubricant 72 interposed therebetween.

As the lubricant 72, among liquids such as water and a fluorine-based cleaning agent, whether or not there is compatibility with the coating layer 12 is determined.
If a material having low compatibility is used, the lubricant and the paint do not mix with each other, so that the paint does not peel off from the coating layer and transfer to the leveling roller 61, and therefore, after the paint is applied. Even if the surface of the developer carrier is not dried until the surface of the developer carrier completely loses its tackiness, the leveling process can be performed, and the manufacturing time of the developer carrier can be reduced.

If powder having a fine particle size is used as the lubricant 72, even if the surface of the coating layer 12 has tackiness,
Since the lubricant adheres to the coating layer 12, the coating can be leveled without transferring the coating to the leveling member. In addition, when the resin-coated metal powder is used as the lubricant, the coating is transferred to the coating layer. If the metal powder acts as a floating electrode or a charge control agent is used as a lubricant, a function layer can be easily formed on the developer carrier, for example, the ability of the developer carrier to impart a charge to the developer is improved. It becomes possible.

The control of the amount of the lubricant applied to the leveling member 61 is performed by controlling the amount of lubricant discharged from the nozzle and the number of rotations of the leveling member. For example, it is possible to control the amount of lubricant applied by bringing an elastic blade into contact with the downstream side of the nozzle.

(Embodiment 8) FIG. 8 is an explanatory view of a method of manufacturing a developer carrier according to another embodiment of the present invention. In order to reduce the semi-drying time and prevent the semi-dry paint from transferring to the leveling member,
It is an improvement. In FIG. 8, a developer carrier 9 has a coating layer 1 having a film thickness unevenness on a base roller 70.
2 is formed by dipping, and the coating layer 12 is urged by a thin plate-shaped leveling member 61 (metal blade) made of stainless steel, phosphor bronze, or the like with a force of 200 g. The wedge portion formed by the leveling member 61 and the developer carrier 9 has a lubricant 7 made of liquid or powder.
2 are loaded. When the developer carrier 9 is rotated in this state, the surface of the coating layer 12 is covered with the lubricant 72, so that the portion of the developer carrier 9 facing the leveling member 61 faces the lubricant 72. Are pressed in a state of being interposed.

As the lubricant 72, if a liquid such as water or a fluorine-based cleaning agent having no compatibility with the coating layer 12 or having low compatibility is used, the lubricant and the paint may be mixed. Since there is no coating, the coating does not peel off from the coating layer and is not transferred to the leveling member 61. Therefore, the coating does not have to be dried until the surface of the developer carrier after coating has completely lost its tackiness. In addition, the leveling process can be performed, and the manufacturing time of the developer carrier can be reduced.

When a powder having a fine particle size is used as the lubricant 72, even if the surface of the coating layer 12 has tackiness,
Since the lubricant adheres to the coating layer 12, the coating can be leveled without transferring the coating to the leveling member. In addition, when the resin-coated metal powder is used as the lubricant, the coating is transferred to the coating layer. If the metal powder acts as a floating electrode or a charge control agent is used as a lubricant, a function layer can be easily formed on the developer carrier, for example, the ability of the developer carrier to impart a charge to the developer is improved. It becomes possible.

In addition, as a method for coating the coating layer surface with the lubricant, as shown in FIG. 9, a lubricant supply roller is provided upstream of a position where the developer carrier 9 and the leveling member 61 face each other. 91, a bias voltage is applied between the developer carrying member and the lubricant supply roller, and the lubricant 72 formed on the developer supply roller is transferred to the coating layer. Any method may be used, such as a method of supplying a lubricant by forming a magnetic brush on a lubricant supply roller using a body.

(Embodiment 9) FIG. 10 is an explanatory view of a method of manufacturing a developer carrier according to another embodiment of the present invention.
FIG. 4 is an explanatory diagram of a method for manufacturing a developer carrying member at low cost by using a dipping method.

In FIG. 10, the shaft 10 is made of a metal such as stainless steel or aluminum, or a resin having conductivity, and has a diameter substantially equal to the diameter of the developer carrier.

Next, the outer periphery of the shaft 10 has a viscosity of 5000
[Cps] magnetic paint is applied. Various methods such as roller coating and spray coating can be considered as the coating method. Here, a dipping method which is easy to manufacture and inexpensive is employed. In the dipping method, the paint wraps around all parts below the surface of the coating liquid, so in this case, after covering the unnecessary end surface with the cap 92, the shaft is immersed in the paint pan 53 filled with the magnetic paint 54. did.

After the surface of the coating layer 12 is semi-dried, the cap 92 is removed from the developer carrier 9 having the coating layer 12 formed on the outer periphery of the shaft, and the positioning rollers 93 for defining the development gap are removed. It is attached. The positioning roller 93 is provided for opposing a distance between the developer carrier and the latent image carrier,
That is, it defines the developing gap. further,
The leveling member 61 is applied to the developer carrier on which the positioning rollers 93 have been attached, and both surfaces are rotated to level the surface of the developer carrier in a semi-dry state. At this time, the thickness of the coating layer is determined by the gap formed by the positioning roller 93 and the leveling member 61.

Since a coating layer is formed directly on the outer periphery of the shaft to form a developer carrier, an elastic layer and the like can be eliminated.
Since the outer shape of the coating layer is directly adjusted, there is no need to strictly control the dimensional accuracy of the shaft, and if the shaft is extruded or molded with a molding die, the polishing of the shaft can be omitted. If the surface is leveled by the leveling member, the polishing of the surface of the coating layer can be omitted, and the developer carrier can be manufactured at low cost.

In the case where the shaft is made of resin or the like, manufacturing man-hours and costs can be reduced by forming notches for driving and the like at the time of molding the shaft. Further, when the shaft is made of a high-strength material such as a metal, if the shaft is formed into a hollow shape, the weight can be reduced even if the developer carrier having a large diameter is made of a metal shaft.

(Embodiment 10) FIG. 11 is an explanatory view of a method of manufacturing a developer carrier according to another embodiment of the present invention.
FIG. 4 is an explanatory diagram of a method of manufacturing a developer carrying member at low cost by using a roll coating method.

In FIG. 11, the shaft 10 is made of a metal such as stainless steel or aluminum, or a resin having conductivity, and has a diameter substantially equal to the diameter of the developer carrier.

Next, the viscosity of 8000
[Cps] magnetic paint is applied. As a coating method, various methods such as a roll coating method and a spray coating method can be considered. Here, a roll coating method capable of applying a high-viscosity paint uniformly and smoothly is adopted.

Further, a positioning roller 93 for defining a developing gap is attached to the developer carrier 9 having the coating layer 12 formed on the outer periphery of the shaft.

Further, the leveling member 61 is applied to the developer carrying member on which the positioning rollers 93 have been attached, and by rotating both of them, the surface of the developer carrier in a semi-dry state is leveled. At this time, the thickness of the coating layer is determined by the gap formed by the positioning roller 93 and the leveling member 61.

The thus obtained developer carrier 9 is
And applied to one-component magnetic flying development.

A one-component developer is formed in a thin layer on the developer carrier, and the electrostatic latent image carrier is arranged facing the developer carrier with a small gap therebetween. And a developing method in which an AC bias is applied is disclosed in JP-A-55-1.
No. 8657, and the like, as a means for enhancing the edge effect of an image. Further, Japanese Patent Application Laid-Open No. 60-8 / 1985 discloses a further improved image sharpness.
No. 0875. In the present invention, the distance between the developer carrier and the latent image carrier is set to 0.5 mm or less, and the developer carrier is molded from a resin in which conductive powder is dispersed. The volume resistivity of the body surface is 10 ⁴ to 10
^By controlling the resistance within a range of ¹² [Ω · cm], the edge effect is improved by preventing discharge from occurring even when a high developing bias is applied.

However, in these (AC / DC) flying development methods, the most important factors that determine the edge intensity and gradation and the amount of background fog of the developer on the non-image area are the development factors. The distance between the developer carrier and the latent image carrier is raised.In order to maintain this distance with high precision, the developer carrier is made of a very rigid material, and the outer shape accuracy is improved by polishing the surface. It had to be strictly managed.

In the present invention, since the outer shape of the coating layer is directly adjusted with the positioning roller set, even if there is a setting error between the positioning roller and the shaft or the outer shape of the shaft fluctuates, the surface of the latent image carrier is not affected. And the distance between the developer and the developer carrier can be made constant.

Therefore, it is not necessary to strictly control the dimensional accuracy of the shaft or the positioning roller covered with the coating layer, and if the shaft is extruded or formed by a molding die, the grinding of the shaft can be omitted. Furthermore, since the coating layer surface is leveled by the leveling member, the polishing of the coating layer surface can be omitted,
It becomes possible to manufacture the developer carrier at low cost.

In this embodiment, a coercive force of 900 [Oe] of B was applied to the outer periphery of a hollow polyurethane shaft having an outer shape of 19 [mm] and a runout of 70 [μm] formed by extrusion.
200 [μm] of a magnetic paint in which a-Fe magnetic powder is dispersed
A thick developer carrier was used, and the volume resistivity of the coating layer was 10 ¹ [Ω · cm].

Further, the developer carrying member has -200 [V]
Vpp = 250 [V], frequency 1 [kHz]
z] to form an image by applying a developing bias on which the AC voltage was superimposed.

As a developer, 30 [wt%] of magnetic powder was used.
The contained polyester-based one-component magnetic developer was used.

(Embodiment 11) In this embodiment, the conductivity is improved on the outer periphery of a developer carrying member in which a shaft and an elastic layer are formed concentrically, and the bleeding of a plasticizer from the elastic layer is prevented. For the purpose, a conductive coating layer is formed.

In the present developer carrier, a polyurethane-based elastic material having a thickness of 6 mm and a volume resistivity of 10 ⁵ Ω · cm is concentrically formed on the outer periphery of a stainless steel shaft having a diameter of 8 mm. The hardness in this state is Asker C
It is 55 [degree] with a type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.). A conductive paint made of polyurethane, carbon black, or the like was applied to the outer periphery by a roll coating method, and the surface condition was adjusted by a leveling device shown in FIG. At this time, the average film thickness of the coating layer was 30 [μm], and the film thickness variation rate was 30 [%].

When the present developer carrier was mounted on the developing device shown in FIG. 2 and an image was formed using a one-component non-magnetic developer, there was no local variation in the film thickness of the coating layer. , 10
Even when continuous printing was performed over 000 sheets, stress concentration did not occur in the coating film, so that defects such as cracks did not occur, and a good image could be continuously formed.

In FIGS. 1 to 12, the present invention is not limited only by the configuration shown in the drawings. In particular, the lubricant is not limited to liquids and powders, but it is also possible to use gas, mist-like liquid, and the like, and the action is not limited to the lubrication action, and promotes drying of the surface of the coating layer. May be provided.

The arrows indicate the rotation direction of each member, but do not limit the present invention. Further, the developing method can be used regardless of whether it is regular development or reversal development. Further, the developer used in the present invention can be used regardless of whether it is a magnetic developer or a non-magnetic developer, and can be a one-component developer, a two-component developer, or a 1.5-component developer. All known developers can be used as the agent, and any of a resin-based developer and a wax-based developer may be used. As is known, the composition of the developer is obtained by adding a magnetic powder, a colorant, an external additive, and other additives to a resin, 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 applied not only to the above-described embodiments but also to a wide range of developing apparatuses such as electrophotography. Particularly, the present invention is effective when applied to printers, copiers, facsimile machines and displays. It is.

[0098]

As described above, according to the developer carrier of the present invention, a developer carrier having a multilayer structure for holding and transporting the developer to a position facing the latent image carrier is provided. The developer carrier is coated with a coating material by at least a roll coating method to form a coating layer, and the film thickness variation rate of at least the seam portion of the coating layer is set to less than 35%. Even when using a developing method in which stress is repeatedly applied to the coating film, stress concentration does not occur in a part of the coating film,
Therefore, it is possible to continue to form a good image without generating cracks or cracks in the coating layer even when used for a long time.

Further, since the coating can be applied to the coating layer without causing a sudden change in film thickness such as a seam, there is no possibility that the developer is clogged on the developer carrier and fog is caused. Further, even if a high-viscosity coating material such as a magnetic coating material is used, the coating can be performed without unevenness in the film thickness, so that the variation in the magnetic binding force due to the film thickness can be reduced. Further, since the head touch of the magnetized head is stabilized, the magnetized unevenness is reduced. Therefore, there is an effect that the magnetic binding force is stable and an image without density unevenness can be obtained.

According to the developer carrier of the present invention, the thickness of the coating film is made uniform before the coating layer is completely solidified. Cracks and the like do not occur, thus improving the yield of the developer carrying member at the time of manufacturing, improving the durability against repeated stress during use, and extending the life of the developer carrying member. Have.

Further, according to the developer carrier of the present invention,
Even if a simple coating method such as a roll coating method is used to coat the coating layer on the base roller, the coating can be performed without generating defects such as seams, so that the developer carrier can be easily manufactured at low cost. It has the effect of being able to.

Furthermore, since the surface state of the coating layer can be made to have a shape corresponding to the surface state of the leveling member by the leveling process, the surface roughness of the leveling member can be controlled by controlling the surface roughness of the leveling member. It is possible to make the surface suitable for development,
This has the effect that a developer carrier having good surface accuracy can be easily manufactured at low cost without subjecting the coated developer carrier to surface treatment such as polishing and sandblasting.

[Brief description of the drawings]

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

FIG. 2 is a schematic cross-sectional view of an image forming apparatus used in an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view of a developer carrier in a comparative example.

FIG. 4 is a schematic cross-sectional view of a developer carrier according to another embodiment of the present invention.

FIG. 5 is an explanatory view of a method for manufacturing a developer carrier in a conventional example.

FIG. 6 is an explanatory diagram of a method for manufacturing a developer carrier according to the embodiment of the present invention.

FIG. 7 is an explanatory view of a method of manufacturing a developer carrier according to another embodiment of the present invention.

FIG. 8 is an explanatory diagram of a method of manufacturing a developer carrier according to another embodiment of the present invention.

FIG. 9 is an illustration of a method of manufacturing a developer carrier according to another embodiment of the present invention.

FIG. 10 is an illustration of a method for manufacturing a developer carrier according to another embodiment of the present invention.

FIG. 11 is an illustration of a method of manufacturing a developer carrier according to another embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view of an image forming apparatus used in another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 latent image carrier, 10 developer carrier, 11 shaft, 12 elastic layer, 50 coating layer, 54 roller coater, magnetic paint, 61 leveling member, 72 lubricant

Claims (3)

[Claims] 1. A multi-layered developer carrier for holding and transporting a developer to a position facing a latent image carrier, wherein the developer carrier is coated with a coating material by at least a roll coating method. A coating layer is formed, and the film thickness variation rate V of at least the joint portion of the coating layer is expressed by the following formula: V <35 [%] V = (R × 100) / t [%] R = tmax−tmin [μm] R: maximum film thickness difference [μm] t: average film thickness [μm] tmax: maximum film thickness [μm] tmin: minimum film thickness [μm]. 2. The developer carrier according to claim 1, wherein the coating layer is applied with a coating material by a roll coating method and then subjected to a leveling treatment. 3. The developer carrier according to claim 1, wherein the coating layer is formed by applying a magnetic paint.