JP2004334013A - Developing device for image forming apparatus, and developer carrier therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer carrier using one-component type developer hardly crashing developer (toner) particles even by the stress of a regulating blade and reduced in the deterioration of the toner, and to provide a developing device using the developer carrier. <P>SOLUTION: A toner carrier 12 being the developer carrier is cylindrically constituted by laminating a conductive elastic layer 12b and a conductive surface layer 12c on substance 12a constituted of conductive resin film or a metallic sheet or the like, and loosely fit on the outer peripheral surface of an elastic roller 11, and rotates together with the roller 11 by frictional force. The thickness of the substance 12a is set to ≥50μm and ≤1mm so as to keep flexibility. Urethane rubber or the like is used for the elastic layer 12b, and rubber hardness is ≥15 and ≤65 by JIS-A. The thickness of the elastic layer is ≥100μm and the surface resistivity of the surface layer is ≥1×10<SP>7</SP>Ω and ≤1×10<SP>12</SP>Ω, then the surface roughness of the surface layer is ≥0.5μm and ≤2μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, and a developer carrier thereof, and more particularly to a developing device using a one-component developer and the developer carrier thereof. is there.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as a conventional electrophotographic copying machine or printer, a photosensitive member is uniformly charged, and an image is exposed thereon to form an image latent image. The formed image latent image is developed with the toner loaded in the developing device to form a toner image of the image, which is transferred to a recording medium, or transferred to an intermediate transfer belt and further transferred to a recording medium. Then, the toner image transferred to the recording medium is heated and fixed by a fixing device to form an image.
[0003]
Developing devices of this type of image forming apparatus include a developing device using a two-component developer composed of a mixture of a magnetic carrier and a toner, and a developing device using a one-component developer using a toner alone. Recently, there has been a demand for downsizing of a developing unit, and a developing apparatus using a one-component developer has been developed. In the following description, the one-component developer may be referred to as a toner, and the developer carrier may be referred to as a toner carrier.
[0004]
A developing device using a one-component developer includes a member called a toner carrier, and adheres the toner to the surface of the toner carrier. The toner adhered by the toner regulating member is formed into a uniform thin layer. Regulate the amount of adhesion. Then, the developing process is performed by bringing the toner carrier having the uniform thin layer toner formed on the surface thereof into contact with the image latent image formed on the photoconductor.
[0005]
In this configuration, a developing roller constituting a toner carrier is configured such that a high-hardness elastic layer is disposed on a flexible elastic layer in a non-adhered state (see Patent Document 1). There has been proposed a configuration in which a developer carrying member composed of a cylindrical thin film member loosely fitted to a member is disposed (see Patent Document 2).
[0006]
FIG. 5 is a cross-sectional view illustrating a developing device using a one-component developer in which a developer carrying member formed of a cylindrical thin film member loosely fitted on the outer circumference of the above-described conventional developing roller is arranged.
[0007]
In FIG. 5, the developing device 100 is arranged adjacent to the photoconductor 120. The developing device 100 is in pressure contact with a developing roller 101, a developer carrying member 102 formed of a tubular thin film member loosely fitted around the outer periphery of the developing roller 101, a guide member 103, and an outer surface of the developer carrying member 102. It is composed of a regulating blade 104 and a casing 105 that supports and stores these members and stores the toner T.
[0008]
The developing roller 101 is made of a conductive material such as aluminum having a rough surface or aluminum having a conductive rubber layer on the surface, and a developing bias voltage is applied.
[0009]
The developer carrying member 102 made of a thin film member is a member carrying the toner, and is a cylindrical film having a peripheral length slightly longer than the outer peripheral length of the developing roller 101, and is loosely fitted on the outer periphery of the developing roller 101. Forms a slight slack. As the developer carrier 102, a soft resin sheet, a resin sheet to which carbon or metal powder is added, a metal thin film of nickel or aluminum, a sheet in which the resin sheet and the metal thin film are laminated, or the like is used.
[0010]
The guide member 103 is a member that presses the developer carrier 102 against the developing roller 101, and has a circular arc shaped along the cylindrical surface of the developing roller 101, and has a developing roller on which the developer carrier 102 is fitted. When the developer carrier 102 is disposed at both ends of the guide member 103 and comes into contact with the developing roller 101, the slack of the developer carrier 102 is concentrated on the opening of the guide member 103 facing the photoconductor 120.
[0011]
The regulating blade 104 is a member that contacts the outer surface of the developer carrier 102 to regulate the layer thickness of the toner attached to the developer carrier 102 and also charges the toner by friction with the toner.
[0012]
In the above configuration, the photoconductor 120 rotates in the direction of arrow a, and the developing roller 101 rotates in the direction of arrow b. With the rotation of the developing roller 101, the developer carrier 102 fitted to the developing roller 101 also moves in the direction of the arrow b, and the toner T stored in the casing 105 adheres to the surface. At the portion where the toner is attached and supplied, the developing roller 101 and the developer carrier 102 are in close contact with each other, so that the regulating blade 104 presses against the developer carrier 102 to make the adhered toner a uniform thin layer. At the same time, the toner adhesion amount can be regulated.
[0013]
When the uniform thin layer toner on the developer carrier 102 moves to a position facing the photoconductor 120 due to the rotation of the developing roller 101 and the developer carrier 102, a slack portion is formed on the developer carrier 102 in this portion. As a result, only the developer carrier 102 contacts the photoconductor 120 with a light and sufficient nip width, and the electrostatic latent image on the photoconductor 120 is developed to form a toner image.
[0014]
[Patent Document 1]
Japanese Patent No. 2701225.
[0015]
[Patent Document 2]
Japanese Patent No. 2586511.
[0016]
[Problems to be solved by the invention]
However, in the developer carrying member including the developing roller and the thin film member, the surface is relatively hard because the developer carrying member is made of resin or metal. For this reason, there is a disadvantage that the stress caused by the regulating blade is large, the toner particles are easily broken, and the toner particles are pulverized and deteriorated. In particular, in the case of a color toner, since the toner particles are soft, the toner particles tend to be finely divided, and there is a disadvantage that the toner deteriorates quickly.
[0017]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a developing device which solves the above-mentioned problems, reduces stress caused by a regulating blade, and causes less deterioration of toner.
[0018]
[Means for Solving the Problems]
The present invention solves the above problems, and the invention of claim 1 is a developer carrier suitable for a developing device of an image forming apparatus, wherein the developer carrier is provided on a conductive base material layer. A conductive elastic layer is laminated, and further has a flexible laminated structure in which a conductive surface layer is laminated thereon. The elastic layer has a JIS-A rubber hardness of 15 to 65 degrees. A developer carrying member.
[0019]
The thickness of the conductive elastic layer is preferably 100 μm or more.
[0020]
The surface resistivity of the conductive surface layer is 1 × 10 ⁷ Ω or more 1 × 10 ¹² It is good to make it below Ω.
[0021]
Further, the surface roughness of the conductive surface layer is preferably in a range of 0.5 μm or more and 2 μm or less.
[0022]
According to a fifth aspect of the present invention, there is provided an elastic roller which is driven to rotate, a cylindrical developer carrier loosely fitted on an outer peripheral surface of the elastic roller, and a developing device which supplies a one-component developer to the developer carrier. A developer supply member, and a regulating member that forms a thin layer of the one-component developer supplied onto the developer carrier in contact with the developer carrier, wherein the developer carrier is electrically conductive. A developing device for an image forming apparatus, comprising a flexible laminated structure in which a conductive elastic layer is laminated on a base material layer, and a conductive surface layer is further laminated thereon. .
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a cross-sectional view illustrating a configuration of a developing device according to an embodiment of the present invention. In the following description, the one-component developer may be referred to as a toner. The developing device 10 is arranged adjacent to the photoconductor 20. The developing device 10 includes an elastic roller 11, a toner carrier 12 as a cylindrical developer carrier loosely fitted around the elastic roller 11, a toner supply roller 13 as a developer supply member, and agitating the toner. The agitating member 14 supplies the toner to the toner supply roller 13, the regulating member 15, and a casing 18 that supports and stores these members and stores the toner T.
[0024]
The elastic roller 11 is made of a conductive material such as aluminum having a conductive rubber layer on the surface, and is configured so that a developing bias voltage is applied from a developing bias power supply 16.
[0025]
The toner carrier 12, which is a developer carrier, will be described in detail later. A conductive elastic layer 12b and a conductive surface layer are formed on a base 12a made of a conductive resin film or a thin metal plate. Reference numeral 12c denotes a member which is laminated and formed into a cylindrical shape. The toner carrier 12 is loosely fitted on the outer peripheral surface of the elastic roller 11, and the frictional force between the outer peripheral surface of the elastic roller 11 and the inner peripheral surface of the toner carrier 12 causes the toner to rotate with the rotation of the elastic roller 11. The carrier 12 also rotates.
[0026]
The toner supply roller 13 that is a developer supply member is a roller that supplies the toner T in the casing 18 to the toner carrier 12, and the stirring member 14 stirs and charges the toner stored in the casing 18. At the same time, the toner is fed toward the toner supply roller 13.
[0027]
The regulating member 15 is a member that regulates the layer thickness of the toner T attached to the surface of the toner carrier 12 to a thin layer having a certain thickness, and charges the toner T by friction. The regulating member 15 is made of a metal material or a material obtained by coating a surface of a base material made of metal or the like with an inorganic material.
[0028]
Next, the developing operation by the developing device 10 will be briefly described. An electrostatic latent image is formed on the photoreceptor 20 by well-known means (not shown), and is rotated in the direction of arrow a. The rotation of the elastic roller 11 in the direction of the arrow b also causes the toner carrier 12 to rotate in the direction of the arrow b. On the surface of the toner carrier 12, a thin layer T of the toner, which is regulated to a certain thickness by the regulating member 15, is formed. Since a developing bias voltage is applied to the toner carrier 12 from the developing bias power supply 16, the electrostatic latent image on the photoconductor 20 is developed with the toner when it comes into contact with the toner carrier 12.
[0029]
By the rotation of the toner carrier 12 in the direction of the arrow b, the surface thereof is successively supplied with toner from the toner supply roller 13 and regulated to a constant thickness by the regulating member 15, so that the developing operation is continued and executed.
[0030]
FIG. 2 is a cross-sectional view illustrating the toner carrier 12 loosely fitted on the outer periphery of the elastic roller 11. The toner carrier 12 is a cylindrical member formed by laminating a conductive elastic layer 12b and a conductive surface layer 12c on a base 12a made of a conductive resin film or a thin metal plate. .
[0031]
The thickness of the base 12a is suitably 50 μm or more and 1 mm or less, preferably 70 μm or more and 300 μm or less. If the thickness is too large, the flexibility is lost, and the contact pressure between the toner carrier and the photoconductor may increase. If the thickness is too thin, the strength may be insufficient.
[0032]
As the resin material constituting the base 12a, polyester, polyamide, polyurethane, acrylic resin, melamine resin, or the like is used, but is not limited thereto. In addition, as a metal forming the base 12a, stainless steel (SUS), a thin plate of nickel, or the like is used, but is not limited thereto. The volume resistivity is 10 ⁴ -10 ¹⁰ Ωcm is appropriate.
[0033]
Examples of the material forming the conductive elastic layer 12b include urethane rubber, silicone rubber, NBR rubber, EPDM rubber, acrylic rubber, isoprene rubber, and the like, but are not limited thereto. Among them, urethane rubber, silicone rubber, EPDM rubber and the like are preferable.
[0034]
The rubber hardness of the conductive elastic layer 12b is set to 15 to 65 degrees in JIS-A, and preferably about 20 to 60 degrees. Storage modulus at room temperature is 10 ⁹ Pa or less is preferable. If it is too soft, problems such as creep may occur, and if it is too hard, it will lose its function as a force relaxation layer. The thickness is preferably at least 100 μm or more. If it is less than 100 μm, the function as a force relaxation layer may be lost. Preferably it is 100 μm or more and 10 mm or less, more preferably 200 μm or more and 4 mm or less. The volume resistivity is 10 ⁴ -10 ¹⁰ Ωcm is appropriate.
[0035]
The thickness of the conductive elastic layer 12b is preferably set to be larger than the thickness of the base 12a. If the thickness of the conductive elastic layer 12b is smaller than the thickness of the base 12a, the function as a force relaxation layer becomes insufficient and the toner particles are easily crushed, which is not appropriate. More preferably, the thickness of the conductive elastic layer 12b is at least twice the thickness of the base 12a.
[0036]
The conductive surface layer 12c is preferably made of a material that easily charges the negatively charged toner (minus toner). For example, urethane resin, polyamide resin, melamine resin, NBR rubber and the like are preferable. The thickness is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 30 μm or less. Surface resistivity is 1 × 10 ⁷ Ω or more 1 × 10 ¹² Ω or less, preferably 5 × 10 ⁷ Ω or more 1 × 10 ¹¹ Ω or less is more preferable. If the resistance value is too high, conduction relaxation is unlikely to occur, and there is a risk of charge-up. If the resistance value is too low, fog may occur due to the developing electric field.
[0037]
The surface roughness (arithmetic mean roughness) Ra of the conductive surface layer 12c is suitably from 0.3 μm to 3 μm, more preferably from 0.5 μm to 2 μm. If the surface roughness is too large, the toner transport amount will increase too much, and if it is too small, the toner transport amount cannot be sufficiently secured. An appropriate transport amount on the toner carrier is about 0.2 to 1.5 mg / cm2, more preferably about 0.3 to 1.0 mg / cm2.
[0038]
In order to adjust the surface roughness, it is preferable to add fine particles of about 3 to 20 μm to the material constituting the surface layer. As the fine particles, PMMA, styrene, polyester, fluorine, silicone, fine particles made of a synthetic resin such as polyamide, fine particles made of an inorganic material such as silica, titanium oxide, alumina, calcium carbonate, and the like can be used, but are not limited thereto. Not something.
[0039]
To adjust the electric resistance value of the conductive surface layer 12c, an electronic conductive agent is added. Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. As the electronic conductive agent, carbon black such as Ketjen black, acetylene black, and furnace black, and fine particles of metal powder and metal oxide can be used. Further, a crosslinking agent such as an isocyanate, an epoxy, or a methylol compound may be added to the conductive surface layer 12c as needed.
[0040]
An easy adhesion treatment may be performed between the conductive elastic layer 12b and the conductive surface layer 12c, and between the base 12a and the conductive elastic layer 12b. As the easy adhesion treatment, a method of providing an adhesion layer of a silane coupling agent, a polymer, or the like, performing a corona discharge treatment, or using both in combination may be employed.
[0041]
The total resistance value of the toner carrier 12 constituted by the above-described materials and processing is 1 × 10 ⁴ Ω ~ 1 × 10 ⁹ Ω is preferred, and more preferably 1 × 10 ⁴ Ω ~ 1 × 10 ⁸ Ω.
[0042]
FIG. 3 is a view for explaining a method of measuring the total resistance value of the toner carrier described above. A conductive sponge roller 32 is inserted into the toner carrier 12, and a part of the peripheral surface of the toner carrier 12 is made of metal. The toner carrier 12 was placed so as to be in contact with the plate 31, and a load F (1 kg) was applied toward the metal plate 31. In this state, a DC voltage E (100 V) was applied from the power supply 33 between the toner carrier 12 and the metal plate 31, and the current I was measured by the ammeter. From the applied DC voltage E and the detected current I, the total resistance value of the toner carrier 12 was calculated.
[0043]
The volume electric resistivity of the base 12a, the volume electric resistivity of the conductive elastic layer 12b, and the surface resistivity of the conductive surface layer 12c are values measured by "Hiresta" manufactured by Mitsubishi Electric Corporation. is there.
[0044]
Here, the toner used in the developing device of this embodiment will be described. As the toner, a one-component developer widely used conventionally can be used, and there is no particular limitation. The one-component developer contains a colorant, a charge control agent, a release agent and the like in a binder resin, and a fluidizing agent and the like are added as necessary. The toner is manufactured from these materials by using a conventionally used method, for example, a pulverization method, an emulsion polymerization method, a suspension polymerization method, or the like.
[0045]
As the binder resin, generally, a polystyrene resin, a styrene-acrylic polymer resin, a polyester resin, or the like is used, and the number molecular weight (Mn) measured by gel permeation chromatography (GPC) is in the range of 1,000 to 15,000, It is preferable to use one having a softening temperature of 80 ° C to 160 ° C and a glass transition point of 50 ° C to 75 ° C.
[0046]
As the coloring agent, known coloring agents can be used, for example, carbon black, aniline black, activated carbon, magnetite, benzidine yellow, permanent yellow, naphthol yellow, phthalocyanine blue, fast sky blue, ultramarine blue, rose bengal, Lakey red or the like can be used, and it is generally preferable to use 2 to 20 parts by weight based on 100 parts by weight of the binder resin.
[0047]
As the charge control agent, known charge control agents can be used, and examples thereof include organic metal complexes such as monoazo metal complexes, aromatic hydroxycarboxylic acid-based metal complexes, and aromatic dicarboxylic acid-based metal complexes, and chelate compounds. In general, it is preferable to use 1 to 10 parts by weight based on 100 parts by weight of the binder resin.
[0048]
As the release agent, a known release agent can be used. For example, polyethylene, polypropylene, carnauba wax, sasol wax and the like can be used alone or in combination of two or more kinds. It is preferable to use 1 to 8 parts by weight to 1 part by weight.
[0049]
Further, as the fluidizing agent, known release agents can be used, for example, silica, titanium oxide, inorganic fine particles such as aluminum oxide, acrylic resin, styrene resin, silicon resin, resin fine particles such as fluororesin. It can be used, and it is particularly preferable to use one that has been made hydrophobic with a silane coupling agent, a titanium coupling agent, silicon oil, or the like. It is preferable to add such a fluidizing agent in a ratio of 0.1 to 3 parts by weight based on 100 parts by weight of the binder resin.
[0050]
The charge amount of the toner is preferably −10 μc / g or more and −60 μc / g or less.
[0051]
The elastic roller 11 will be described. As shown in FIGS. 1 and 2, the elastic roller 11 has a toner carrier 12 loosely fitted around its outer periphery. The elastic roller 11 has an Asker C hardness around a conductive core 11a such as aluminum. Conductive rubber or foam of 60 degrees or less is arranged and configured. For example, rubber or foam such as urethane, silicone, EPDM, NBR, etc. can be used. Electric resistance is 1 × 10 ⁶ Ω or less, preferably 1 × 10 ⁴ It is better to be Ω or less. With this configuration, when the developing bias power supply 16 is connected to the metal core 11 a, a developing bias voltage is applied to the toner carrier 12.
[0052]
The developing conditions will be described. As described above, the developing bias voltage is applied to the toner carrier 12. It is preferable that a voltage of the same potential or about -500 V with respect to the developing bias voltage is applied to the regulating member 15 in contact with the toner carrier 12. This is for charging and injecting the toner.
[0053]
Further, it is preferable that a voltage lower than the same potential or about 500 V from the developing bias voltage applied to the toner carrier 12 is applied to the toner supply roller 13. This is necessary in order to smoothly supply the toner to the toner carrier 12.
[0054]
The rotation speed of the toner carrier 12 is set to be 1 to 2 times the rotation speed of the image carrier 20, but is preferably about 1.1 to 1.6 times, and both rotate in the same direction at the contact portion. As a result, the toner charge amount on the toner carrier 12 and the toner conveyance amount can be maintained at appropriate amounts.
[0055]
Next, a description will be given of a plurality of examples and comparative examples in which the materials and thicknesses of the base material of the toner carrier, the conductive elastic layer, and the conductive surface layer are changed, and performance evaluation results.
[0056]
[Example 1]
Manufacturing process: as substrate, inner diameter 16 mm, thickness 150 μm, circumference 230 mm, volume electric resistivity 10 made of PET resin ⁵ A cylindrical resin thin film of Ωcm is inserted into a metal core having an outer diameter of 16 mm, and the surface of the resin thin film is subjected to an easy adhesion treatment. ⁴ Wrap an EPDM rubber tube with Ωcm and rubber hardness of 40 degrees, heat-treat and bond. Next, a polyurethane resin emulsion (MRX-100) containing silica fine particles having an average particle diameter of 10 μm and carbon black was applied by a ring coater and heat-treated, and a metal core was removed to obtain a toner carrier.
[0057]
Physical properties: thickness of conductive surface layer = 15 μm, surface resistivity = 10 ⁹ Ω, surface roughness Ra = 1.3 μm, total resistance value of toner carrier = 10 ⁶ Ω.
[0058]
[Example 2]
Manufacturing process: as base material, inner diameter 16 mm, thickness 100 μm, circumference 230 mm, volume electric resistivity 10 made of polyamide resin ⁶ A cylindrical resin thin film of Ωcm is inserted into a metal core having an outer diameter of 16 mm, and the surface of the resin thin film is subjected to easy adhesion treatment. Then, the surface is placed in a mold having an inner diameter of 16.8 mm. Pour silicone rubber (rubber hardness 20 degrees) and heat-treat. Next, a polyamide resin containing silica fine particles having an average particle diameter of 5 μm and carbon black was applied by a ring coater and subjected to heat treatment, and a metal core was pulled out to obtain a toner carrier.
[0059]
Physical properties: thickness of conductive surface layer = 10 μm, surface resistivity = 10 ⁹ Ω, surface roughness Ra = 0.7 μm, total resistance of toner carrier = 10 ⁷ Ω.
[0060]
[Example 3]
Manufacturing process: a base material made of a polyamide resin having an inner diameter of 16 mm, a thickness of 300 μm, a circumference of 230 mm, and a volume resistivity of 10 ⁵ A cylindrical resin thin film of Ωcm is inserted into a metal core having an outer diameter of 16 mm, and the surface of the resin thin film is subjected to an easy adhesion treatment. ⁴ Wrap an EPDM rubber tube with Ωcm and rubber hardness of 40 degrees, heat-treat and bond. Next, a polyurethane resin emulsion (MRX-100) containing silica fine particles having an average particle diameter of 10 μm and carbon black was applied by a ring coater, heat-treated, and a metal core was removed to obtain a toner carrier.
[0061]
Physical properties: thickness of conductive surface layer = 15 μm, surface resistivity = 10 ¹⁰ Ω, surface roughness Ra = 1.8 μm, total resistance value of toner carrier = 10 ⁶ Ω.
[0062]
[Example 4]
Manufacturing process: a base material made of a polyamide resin having an inner diameter of 16 mm, a thickness of 150 μm, a circumference of 230 mm, and a volume resistivity of 10 ⁶ A cylindrical resin thin film of Ωcm is inserted into a metal core having an outer diameter of 16 mm, and the surface of the resin thin film is subjected to easy adhesion treatment. ⁴ Wrap an EPDM rubber tube with Ωcm and rubber hardness of 60 degrees, heat-treat and bond. Next, a polyurethane resin emulsion (MRX-100) containing silica fine particles having an average particle diameter of 10 μm and carbon black was applied by a ring coater and subjected to heat treatment, and a metal core was removed to obtain a toner carrier.
[0063]
Physical properties: thickness of conductive surface layer = 20 μm, surface resistivity = 10 ⁸ Ω, surface roughness Ra = 2.0 μm, total resistance value of toner carrier = 10 ⁵ Ω.
[0064]
[Comparative Example 1]
Manufacturing process: A resin thin film made of a polyamide resin and having an inner diameter of 16 mm, a thickness of 150 μm, and a circumference of 230 mm was used as a base material.
[0065]
Physical properties: surface resistivity = 10 ⁸ Ω, surface roughness Ra = 1.3 μm, total resistance value of toner carrier = 10 ⁵ Ω.
[0066]
[Comparative Example 2]
Manufacturing process: A polyurethane resin emulsion (MRX-100) containing silica fine particles having an average particle diameter of 10 μm and carbon black was coated on the surface of a cylindrical EPDM rubber tube having an inner diameter of 16 mm, a thickness of 2 mm, and a circumference of 230 mm and a rubber hardness of 40 °. The resultant was applied by a ring coater and heat-treated, and the metal core was removed to obtain a toner carrier.
[0067]
Physical properties: thickness of conductive surface layer = 15 μm, surface resistivity = 10 ⁹ Ω, surface roughness Ra = 1.3 μm, total resistance value of toner carrier = 10 ⁶ Ω.
[0068]
[Performance evaluation results]
The performance evaluation was carried out for (A) a change in the average particle diameter of the toner, (B) a change in the surface state of the toner carrier, and (C) a state of image fog.
[0069]
FIG. 4 is a diagram showing physical properties and performance evaluation results of Examples 1 to 4 and Comparative Examples 1 and 2 of the toner carrier described above.
[0070]
(A) The average particle diameter of the toner is changed by loading a cyan toner having an average particle diameter of 6.5 μm manufactured by an emulsion polymerization method into a developing device using a laser printer LP-2400 manufactured by Minolta Co., Ltd. The toner carriers of Examples 1 to 4 and Comparative Examples 1 and 2 were fitted and mounted on elastic rollers. After passing 1000 sheets of white paper through the developing device without forming an image with a laser printer, the average particle size of the toner was measured. "X" indicates that the average particle diameter changed by 0.5 μm or more smaller than the toner in the initial state (unused toner), and "O" indicates that the average particle diameter changed less than 0.5 μm. Examples 1 to 4 and Comparative Example 2 were acceptable, and Comparative Example 1 was unacceptable because of a large change in the average particle size of the toner.
[0071]
(B) The change in the surface state of the toner carrier was visually observed after passing 1,000 sheets of white paper through the developing device without forming an image with a laser printer. Those that did not change from the initial state (including those that hardly changed) were indicated by “O”, and those in which cracks and the like occurred were indicated by “X”. Examples 1 to 4 and Comparative Example 1 passed, while Comparative Example 2 cracked and failed.
[0072]
(C) The image fogging condition is as follows. In a high temperature and high humidity environment, the developing bias is set to minus 100 V (−100 V), the photoconductor surface potential is set to −700 V (−700 V), and the developing electric field (600 V) is large. Printing was performed, and fog on the surface of the photoreceptor was visually observed. Those in which fog was not observed were indicated by "O", and those in which fog was observed were indicated by "x". Examples 1 to 4 and Comparative Examples 1 and 2 all passed.
[0073]
The above-described embodiments of the present invention also include the following inventions.
(1) The developer carrier according to any one of claims 1 to 4, wherein a thickness of the conductive elastic layer is larger than a thickness of the conductive base layer.
(2) The developer carrier according to any one of claims 1 to 4, wherein the conductive base layer is made of a resin.
(3) In the developer carrier according to any one of claims 1 to 4, the JIS-A rubber hardness of the conductive elastic layer is from 20 degrees to 60 degrees.
A developer carrier characterized by the following.
[0074]
【The invention's effect】
As described in detail above, the developer carrier suitable for the developing device using the one-component developer of the image forming apparatus according to the first aspect of the present invention has a conductive elastic layer on the conductive base material layer. The conductive elastic layer has a flexible laminated structure in which a layer is laminated and a conductive surface layer is further laminated thereon, and the conductive elastic layer has a JIS-A rubber hardness of 15 to 65 degrees. It is a developer carrier.
[0075]
According to this configuration, the surface of the developer carrier is relatively soft, and the developer particles are less likely to be broken by the stress of the regulating blade. Therefore, the developer particles are less likely to be finely divided, and the developer is less deteriorated. Can be provided.
[0076]
An image forming apparatus according to a fifth aspect of the present invention includes an elastic roller that is driven to rotate, a cylindrical developer carrier loosely fitted on the outer peripheral surface of the elastic roller, and one of the developer carrier. A developer supply member that supplies a component developer; and a regulating member that contacts the developer carrier and forms a one-layer developer supplied on the developer carrier in a thin layer, the developing device comprising: The agent carrier has a flexible laminated structure in which a conductive elastic layer is laminated on a conductive base layer, and a conductive surface layer is further laminated thereon. It is a developing device of the forming device.
[0077]
According to this configuration, as in the first aspect of the invention, the surface of the developer carrying member is relatively soft, and the developer particles are not easily broken even by the stress caused by the regulating blade. It is possible to provide a developing device of the image forming apparatus in which the deterioration of the image is small.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a developing device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a toner carrier loosely fitted on the outer periphery of an elastic roller.
FIG. 3 is a diagram illustrating a method for measuring the total resistance value of the toner carrier.
FIG. 4 is a diagram showing physical properties and performance evaluation results of Examples and Comparative Examples of a toner carrier.
FIG. 5 is a cross-sectional view illustrating a developing device using a one-component developer in which a conventional developer carrier is disposed.
[Explanation of symbols]
10 Developing device
11 Elastic roller
12 Toner carrier
12a substrate
12b conductive elastic layer
12c conductive surface layer
13 Toner supply roller
14 Stirring member
15 Regulation members
16 Development bias power supply
18 Casing
20 Photoconductor

Claims (5)

A developer carrier suitable for a developing device of the image forming apparatus,
The developer carrier, a conductive elastic layer is laminated on a conductive base material layer, and further has a flexible laminated structure in which a conductive surface layer is laminated thereon,
The developer carrier, wherein the elastic layer has a JIS-A rubber hardness of 15 degrees or more and 65 degrees or less. 2. The developer carrier according to claim 1, wherein said conductive elastic layer has a thickness of 100 [mu] m or more. 3. The developer carrier according to claim 2, wherein the surface resistivity of the conductive surface layer is 1 × 10 ⁷ Ω or more and 1 × 10 ¹² Ω or less. 4. The developer carrier according to claim 1, wherein a surface roughness of the conductive surface layer is 0.5 μm or more and 2 μm or less. 5. An elastic roller driven to rotate,
A cylindrical developer carrier loosely fitted to the outer peripheral surface of the elastic roller;
A developer supply member for supplying a one-component developer to the developer carrier,
A regulating member that forms a thin layer of a one-component developer supplied on the developer carrier in contact with the developer carrier,
The developer carrier is characterized in that it has a flexible laminated structure in which a conductive elastic layer is laminated on a conductive base layer, and a conductive surface layer is further laminated thereon. Developing device of the image forming apparatus.

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