JP2005326484A - One-component developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-component developing device where toner on a toner carrier served for development is uniformly charged with high charging efficiency while restraining its deterioration, and where toner charging performance is maintained over a long term. <P>SOLUTION: The one-component developing device 10 has a toner charging member 17 arranged in contact with the toner carrier 12 on a more downstream side than a toner regulating member 15 and on a more upstream side than a developing area D in the moving direction of the surface of the toner carrier 12, and the toner charging member 17 is a high polymer film supported by a fixed electrode 20. The arithmetic average roughness Ra of the surface of the high polymer film opposed to the toner carrier 12 is 0.01-2μm. The arithmetic average roughness Ra of the surface of the high polymer film is smaller than the arithmetic average roughness Ra of the surface of the toner carrier 12. The surface roughness is adjusted, for example, by containing a roughness adjusting agent in the film, and the content in such a case is about 2-20 pts.wt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a one-component developing device for developing an electrostatic latent image formed on an electrostatic latent image carrier in an image forming apparatus such as an electrophotographic copying machine or a printer.

  In an image forming apparatus such as a copying machine or a printer, an electrostatic latent image corresponding to an image to be formed is formed on an electrostatic latent image carrier and developed by a developing device. As such a developing device, a one-component developing device using a one-component developer mainly composed of toner is known and widely used.

  In the one-component developing device, the toner is held on the surface of the toner carrying member and conveyed to a developing region facing the image carrying member, and a regulating member is pressed against the surface of the toner carrying member in the middle of the developing region. The amount of toner conveyed to the surface is regulated, and in the development area, the toner carrier is brought into contact with or close to the latent image portion on the image carrier to supply the toner, and the latent image is developed.

For such a one-component developing device, toner chargeability, durability, environmental resistance, toner adhesion resistance, and the like have been cited as performance required for the toner carrier and the entire developing device.
In particular, when a highly hygroscopic toner such as a polymerized toner is used as a toner, or when a developer is used for a long time, the toner charge amount is decreased, and quality deterioration such as generation of background fogging may occur accordingly. It has been viewed as a problem.

  In order to solve this, it is necessary to install a member (charging roller) for charging the toner on the developing roller, which is a toner carrying member, by discharging (JP 2000-315014 A, JP 2001-34046 A) and the like. Proposed. By adopting such a toner charging member, the chargeability of the toner is improved accordingly, and problems such as toner background fogging are reduced.

JP 2000-315014 A JP 2001-34046 A

However, when the charging roller is disposed in contact with the developing roller as a toner charging member, the following problem occurs.
(1) A load is applied between the developing roller and the charging roller, which may increase the torque of the entire developing device and cause the developer deterioration.
(2) Since the dischargeable area is not sufficient, the toner charging effect may not be sufficiently obtained depending on the toner.
(3) When the charging roller is driven to rotate, there is no speed difference from the developing roller, so it cannot be scraped off when the surface of the charging roller is contaminated.

  Therefore, the present invention holds the toner on the surface of the toner carrying member and transports it to the developing region, and regulates the amount of toner transported to the developing region in the middle of the transportation by a regulating member, A one-component developing device for developing an electrostatic latent image by supplying the toner from a toner carrier to an electrostatic latent image portion formed on the electrostatic latent image carrier, on the toner carrier to be developed It is an object of the present invention to provide a one-component developing device capable of charging toner with high charging efficiency while suppressing deterioration of the developer and maintaining toner charging performance over a long period of time.

  Another object of the present invention is to provide such a one-component developing apparatus that can uniformly charge the toner on the toner carrier to be used for development.

  In the present invention, the toner is held on the surface of the toner carrying member and conveyed to the developing area, and the amount of toner conveyed to the developing area in the middle of the conveyance is regulated by the regulating member, and the toner is transferred to the toner in the developing area. A one-component developing device for supplying an electrostatic latent image portion formed on an electrostatic latent image carrier from a carrier to develop the electrostatic latent image, wherein the regulating member moves in a moving direction of the surface of the toner carrier. The toner charging member is disposed in contact with the toner carrying member on the downstream side and on the upstream side of the developing region, and the toner charging member provides a one-component developing device which is a polymer film supported by a fixed electrode. .

Since this developing device employs a polymer film (resin film, rubber film, etc.) as a toner charging member, it has the following advantages.
(1) The polymer film can be bent greatly even under a low pressure, and can be softly brought into contact with the toner carrier under a low contact pressure, thereby suppressing the torque increase of the developing device and reducing the stress on the toner. And toner deterioration is suppressed.
(2) The polymer film can be brought into contact with a large nip width along the surface of the toner carrier, thereby ensuring a wide discharge area and making it stably contactable, so that the toner charging efficiency is high and the toner is sufficiently charged. Can be made.
(3) The polymer film supported by the fixed electrode can be brought into contact with the toner carrier with a relative speed difference, so that the toner hardly adheres, and the deterioration of the charging performance due to the toner adhesion is suppressed for a long time. The

As described above, according to the developing device of the present invention, since the toner charging member for charging the toner before being subjected to the development is used that includes the polymer film, the developer is charged in a state where the developer is hardly deteriorated. The toner can be charged at a high rate, and the charging performance is maintained for a long time.
As a result, the toner on the toner carrier to be developed can be stably charged over a long period of time, and a high quality image can be formed accordingly.

  As described above, the polymer film can be deformed along the surface of the toner carrier to obtain a wide contact area with the toner carrier, but the discharge is evenly distributed over the entire area including the contact area and the vicinity thereof. By causing it to occur, the toner can be charged more uniformly. For this purpose, it is important to control the film surface roughness.

  Therefore, in the developing device according to the present invention, an example in which the arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier is 0.01 μm to 2 μm can be given. By controlling the arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier within this range, the toner held on the toner carrier and transported to the development region can be more uniformly and stably charged. it can.

  When the arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier is less than 0.01 μm, the distance between the toner layer and the toner layer is determined by Paschen's law anywhere on the surface of the film in contact with the toner. It will be shorter than the easy distance. Although there are slightly portions at the entrance side and the exit side of the contact portion that are easy to discharge as determined by Paschen's law, this does not provide uniform and sufficient discharge. As a result, the toner cannot be charged sufficiently and the charge amount becomes non-uniform. If it exceeds 2 μm, the region where the film surface and the toner layer are in contact with or close to each other is limited to the vicinity of the large crest portion on the film surface. A uniform and sufficient discharge cannot be obtained for the toner. As a result, the toner cannot be charged sufficiently and the charge amount becomes non-uniform.

The arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier is preferably smaller than the arithmetic average roughness Ra of the toner carrier surface.
The reason is that when the film surface roughness is larger than the surface roughness of the toner carrier, a part of the toner conveyed by the toner carrier is easily transferred to the film. The toner accumulated on the film surface at the nip portion between the film and the toner carrier obstructs discharge and causes a charging failure of the toner.

  The polymer film surface roughness can be adjusted by various methods. A typical example is a method of adding a roughness adjusting agent to the polymer film. In this case, the content of the roughness adjusting agent may be about 2 to 20 parts by weight with respect to 100 parts by weight of the base material after drying or the resin solid content. The arithmetic average roughness Ra of 0.01 μm to 2 μm can be obtained with a content in this range.

  As described above, according to the present invention, the toner is held on the surface of the toner carrier and transported to the developing region, and the amount of toner transported to the developing region during the transport is regulated by the regulating member, A one-component developing device that develops an electrostatic latent image by supplying toner from a toner carrier to an electrostatic latent image portion formed on the electrostatic latent image carrier in a development region. It is possible to provide a one-component developing device that can charge the toner on the toner carrying member with high charging efficiency while suppressing the deterioration of the developer and can maintain the toner charging performance over a long period of time.

  In addition, according to the present invention, it is possible to provide such a one-component developing device that can uniformly charge the toner on the toner carrier used for development.

Embodiments of the present invention will be described below.
(1) Overall Developing Device FIG. 1 is a diagram showing an outline of the configuration of a developing device 10 according to an embodiment of the present invention.
The developing device 10 includes a device case 19. The inside of the case 19 is partitioned into two chambers 19a and 19b by a partition wall 190. One chamber 19a is a toner storage chamber for storing a one-component toner t, and a rotary agitator 13 for stirring the toner t is installed therein.

  The other chamber 19b is a toner supply chamber for supplying toner to the toner carrier, and the toner carrier 12 is disposed in the lower part. Here, the toner carrier 12 is in the form of a roller that is driven to rotate clockwise in the figure, and is disposed in contact with or in proximity to the electrostatic latent image carrier 11 in the image forming apparatus. Here, the image carrier 11 is a photosensitive drum 11 that is driven to rotate counterclockwise in the drawing. The surface of the photosensitive drum 11 is charged to a predetermined potential by a charging device (not shown), and an electrostatic latent image can be formed by exposing the charged area to an image from an image exposure device (not shown). A region where the toner carrier 12 faces the image carrier 11 is a development region D.

A toner supply roller 14 is also provided in the toner supply chamber 19b. The toner supply roller 14 is disposed in contact with the toner carrier 12 and is rotated to supply the toner t to the toner carrier 12.
The partition wall 190 has an opening 191, and the toner t stirred by the agitator 13 in the toner storage chamber 19 a can move from the opening 191 to the chamber 19 b, and the toner t that has moved is transferred by the toner supply roller 14. The toner can be supplied to the surface of the toner carrier 12.

  Further, a toner regulating member 15 that regulates the layer thickness of the toner t supplied from the toner supply roller 14 is disposed in pressure contact with the toner carrier 12. The toner regulating member 15 regulates the layer thickness of the toner t on the toner carrier 12 moving to the developing region D to a predetermined thickness to form a thin toner layer and frictionally charge the toner t.

  Further, a developing bias power source 16 is connected to the toner carrier 12, and a developing bias voltage can be applied to the toner carrier 12 disposed in contact with or close to the image carrier 11. In developing the electrostatic latent image, a charge is applied to the toner t on the toner carrier 12 by applying a developing bias voltage to the toner carrier 12, and the electrostatic latent image formed on the image carrier 11 is applied to the toner t. This is applied to the image portion to visualize it.

  In the illustrated developing device, a toner charging film 17 for charging the toner t is further disposed in contact with the downstream side of the toner regulating member 15 and the upstream side of the developing region D in the moving direction of the surface of the toner carrier 12. The film 17 is supported by a fixed electrode 20 held by the device case 19. A voltage can be applied to the toner charging film 17 from the power source 18 via the electrode 20. At this time, the voltage applied to the film 17 is equal to or higher than the discharge start voltage for the toner t on the toner carrier 12 and is a predetermined DC voltage having the same polarity as the toner t. The toner t can be charged by the discharge between the toner carrier 12 and the toner charging film 17 by applying the voltage.

The absolute value of the toner charge amount is preferably about 20 μC / g to 60 μC / g.
Toner transport amount to the developing region D by the toner carrying member 12 is regulated to about ² 2g / m ² ~20g / m by the regulating member 15. If it exceeds 20 g / m ² , the amount of toner becomes too large and it becomes difficult to be sufficiently charged by the charging film 17.

(2) Toner Charging Film 17 As shown in FIG. 1, the charging film 17 is cantilevered by a fixed electrode 20 held by an apparatus case 19. FIG. 2 is a plan view of the charging film 17 and the like.

  A voltage is applied to the charging film 17 from the power source 18 through the electrode 20. The lateral width w1 of the charging film 17 may be approximately the same as the lateral width w2 of the toner carrier 12, or may be slightly longer or slightly shorter. The lateral width w3 of the electrode 20 may be the same as the lateral width w1 of the charging film 17, or may be slightly longer or slightly shorter. When it is desired to charge only the toner t in the portion of the lateral width w2 of the toner carrier 12 that directly contributes to development, the lateral width w1 of the film 17 is preferably slightly shorter than the lateral width w2 of the toner carrier 12.

  The charging film 17 is a polymer film with adjusted conductivity. There is no particular limitation on the polymer constituting the film. For example, polyester resin, polycarbonate resin, acrylic resin, polyethylene resin, polypropylene resin, urethane resin, polyamide resin, polyimide resin, polysulfone resin, polyether ketone resin, vinyl chloride resin, vinyl acetate resin, silicone resin, fluorine resin, etc. A film made of, or a rubber film made of silicone rubber, urethane rubber, nitrile rubber, natural rubber, isoprene rubber or the like can be used, but is not limited thereto.

Examples of the thickness of the charging film 17 include 10 μm to 1 mm, preferably 10 μm to 200 μm. If it is too thin, the strength will be insufficient, and if it is too thick, it will be difficult to uniformly contact the toner carrier, or the contact nip with the toner carrier will be small.
In addition, the charging film may have a single layer structure, or may have a structure of two or more layers as necessary.

  In order to obtain an appropriate electric resistance, the charging film 17 may be added with a conductive agent to the bulk of the film (film material) or the film surface as necessary. Examples of such a conductive agent include an electronic conductive agent or an ionic conductive agent. Examples of the electronic conductive agent include, but are not limited to, carbon black such as kettin black, acetylene black, and furnace black, metal powder, and metal oxide fine particles. Examples of the ionic conductive agent include cationic compounds such as quaternary ammonium salts, anionic compounds, nonionic compounds having an alkylene oxide group in the side chain, and other ionic polymer materials. .

By adding the above conductive agent, the surface resistivity of the film is 10 ⁵ Ω / □ to 10 ¹¹ Ω / □, more preferably 10 ⁶ Ω / □ to 10 ¹⁰ Ω / □, and even more preferably 10 ^7. Can be adjusted to Ω / □ to 10 ⁹ Ω / □. If the surface resistivity falls below 10 ⁵ Ω / □, excessive current may flow before the discharge start voltage is reached, and the discharge start voltage may not be reached. If it exceeds 10 ¹¹ Ω / □, The discharge start voltage is excessively increased, which is not preferable. In the case of a film, since surface conduction is the main, control of surface resistivity is important.
The surface resistivity of the film 17 can be measured by, for example, a measuring instrument Hiresta manufactured by Mitsubishi Chemical Corporation.

  The discharge from the toner charging film 17 occurs when the distance between the film surface and the toner layer on the toner carrier 12 is a distance at which discharge is easily determined by the Patschen law. The film surface roughness is an important parameter for causing an appropriate discharge to sufficiently charge the toner, and is desirably set appropriately. The roughness of the film surface facing the toner carrier 12 is preferably in the range of 0.01 μm to 2 μm in terms of arithmetic average surface roughness Ra.

  When the film surface roughness exceeds 2 μm, the area where the film surface and the toner layer are in contact with or close to each other is limited to the area near the large crest of the film surface. A uniform and sufficient discharge cannot be obtained for the toner on the body.

When the film surface roughness becomes smaller than 0.01 μm, the distance to the toner layer becomes shorter than the distance at which the toner layer is easily discharged determined by the Paschen's rule, regardless of where the film surface is in the contact portion with the toner. Slightly a portion having a dischargeable distance determined by the Patzchen's law is formed on the entrance side and the exit side of the contact portion, but this alone alone does not provide uniform and sufficient discharge.
The surface roughness of the film can be measured by using, for example, an atomic force microscope Nanoscope IIIa / Dimension 3100 manufactured by Bico.

  In order to obtain an appropriate surface roughness of the toner charging film, a roughness adjusting agent may be added to the bulk of the film (film material) or the film surface as necessary. Examples of the roughness adjuster include, but are not limited to, inorganic pigments such as silica, titanium oxide, zinc oxide, alumina, and calcium carbonate, and organic pigment fine particles such as PMMA fine particles. Further, a conductive agent such as carbon black may be used as the roughness adjusting agent. Examples of carbon black include, but are not limited to, ketchin black, acetylene black, furnace black, and the like. Although the size of the fine particles depends on the amount to be added, the diameter is generally preferably 5 μm or less. Larger particles make it difficult to obtain a uniform and sufficient discharge.

  The surface roughness of the toner charging film 17 directed to the toner on the toner carrier is preferably smaller than the surface roughness of the toner carrier 12. When the film surface roughness is larger than the surface roughness of the toner carrier 12, a part of the toner conveyed by the toner carrier 12 is easily transferred to the film 17. The toner accumulated on the film surface at the nip portion between the film 17 and the toner carrier 12 hinders discharge and causes a charging failure of the toner.

Furthermore, for the following reasons, the content of the roughness adjusting agent is preferably about 2 to 20 parts by weight with respect to 100 parts by weight of the base material after drying.
When the content of the roughness adjusting agent decreases, even if the particle size of the roughness adjusting agent is increased, the film 17 is tucked to the toner layer, and a gap that can be discharged from the toner layer is secured. Can not. On the other hand, regardless of the type of the roughness adjusting agent and the particle size, generally, if the content of the roughness adjusting agent is too much, the bending resistance of the film is lowered. That is, if image formation by electrostatic latent image development is repeated in the developing device, or if the developing device is used for a long time, the film surface may be cracked, which may cause an image error. Therefore, the content of the roughness adjusting agent is preferably about 2 to 20 parts by weight.

(3) About the toner carrier 12 The toner carrier 12 in the illustrated example is a roller type, but may be a belt type. FIG. 3 is a cross-sectional view illustrating the configuration of the roller type toner carrier 12. The toner carrier 12 is configured by providing a base layer 22 on a metal core 21 made of aluminum or the like, and further providing a surface layer 23 on the base layer 22.

The base layer 22 is made of a conductive rubber layer having a hardness of 50 degrees or less, and the thickness is preferably about 0.5 mm to 6 mm. The volume resistivity of the conductive rubber layer is preferably about 1 × 10 ³ Ω · cm to 1 × 10 ⁸ Ω · cm. As a material for the conductive rubber layer, silicone rubber, urethane rubber, EPDM rubber, nitrile rubber, fluorine rubber and the like can be used, but the material is not limited to these. And in order to provide electroconductivity, a conductive agent is mixed and an electrical resistance value is adjusted.
As the conductive agent, the same conductive agent as that added to the film can be used.

  The surface layer 23 is preferably a film of a nitrogen-containing resin such as a urethane resin, a polyamide resin, or a nitrile resin from the viewpoint of chargeability. The thickness is about 1 μm to 100 μm, preferably about 5 μm to 30 μm.

The surface resistivity of the surface layer 23 is 1 × 10 ⁷ Ω / □ or more and 1 × 10 ¹² Ω / □ or less, preferably 1 × 10 ⁸ Ω / □ or more and 1 × 10 ¹¹ Ω / □ or less. The total surface resistivity of the toner carrier with the surface layer provided is preferably about 1 × 10 ⁴ Ω / □ or more and about 1 × 10 ⁸ Ω / □ or less.
If the surface resistivity of the surface layer 23 is less than 1 × 10 ⁷ Ω / □, local conduction to the toner carrier occurs, and in the worst case, there is a risk of burning. If it exceeds 10 ¹² Ω / □, there is a risk of charge-up and ghosting.
The surface resistivity of the surface layer 23 can also be measured by, for example, a measuring instrument Hiresta manufactured by Mitsubishi Chemical Corporation.

  The total resistance of the toner carrier with the surface layer provided can be measured, for example, by the technique shown in FIG. That is, the toner carrier is pressed against the metal electrode with a load of 1 kg, a DC voltage of 100 V is applied to the conductive substrate (usually a core metal) of the toner carrier, and the toner carrier and the metal electrode from the toner carrier conductive substrate. The current flowing through the metal electrode through the nip is measured and calculated from the DC voltage and current.

  The arithmetic average surface roughness Ra of the surface layer 23 is preferably 0.3 μm or more and 5 μm or less, and more preferably 0.7 μm or more and 3 μm or less. Although the method of adjusting the surface roughness Ra of the surface layer surface is not particularly limited, an example of adding a roughness adjusting agent to the material forming the surface layer can be given. As the roughness adjusting agent, fine particles of organic material such as acrylic resin and fine particles of inorganic material such as silica and alumina are desirable. Moreover, you may add crosslinking agents, such as an isocyanate compound, a methylol compound, an epoxy compound, to the material which forms a surface layer as needed. Furthermore, an adhesive layer such as a silane coupling agent or a polymer may be provided between the surface layer 23 and the base layer 22.

  FIG. 4 is a cross-sectional view illustrating the configuration of an example of the belt-type toner carrier (toner carrier 30). The belt-type toner carrier 30 is an endless belt which is provided with a conductive sponge roller or the like and is carried by the belt, and can be used in place of the toner carrier 12 described above.

The belt-type toner carrier 30 is configured by providing a surface layer 32 on a base layer 31. The base layer 31 is a thin layer made of a synthetic resin or metal having a thickness of 10 μm to 1 mm, preferably 100 μm to 300 μm. In the case of a metal, nickel or the like is used. When a synthetic resin is used, polyester, polyamide, polyethylene, polyimide, polycarbonate, or the like is used. In order to provide conductivity, a conductive agent is added as in the case of the toner carrier 12.
The surface layer 32 may be formed in the same manner as the surface layer 23 in the toner carrier 12.

(4) Toner t The toner t used in the developing device of the embodiment is not particularly limited, and a toner generally used conventionally can be used. In general, a binder resin containing a colorant, a charge control agent, a release agent or the like is used, and a fluidizing agent or the like is added as necessary.

  Such a toner t can also be produced by a known method that has been generally employed conventionally, for example, by employing a pulverization method, an emulsion polymerization method, a suspension polymerization method, or the like. .

  The binder resin used for the toner t has a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) in the range of 1000 to 15000, and a softening temperature in the range of 80 to 160 ° C. Moreover, it is preferable to use a glass transition point in the range of 50 ° C to 75 ° C.

  In addition, as the above colorant, known ones that are conventionally used can be used, such as carbon black, aniline black, activated carbon, magnetite, benzidine yellow, permanent yellow, naphthol yellow, phthalocyanine blue, First sky blue, ultramarine blue, rose bengal, lake red and the like can be used, and it is generally preferably used in a ratio of 2 to 20 parts by weight with respect to 100 parts by weight of the binder resin.

  In addition, as the above charge control agent, known ones generally used in the past can be used. For example, monoazo metal complexes, aromatic hydroxycarboxylic acid metal complexes, aromatic dicarboxylic acid metals An organometallic complex such as a complex, a chelate compound, or the like can be used. In general, it is preferably used at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  In addition, as the above mold release agent, known ones that have been generally used can be used. For example, polyethylene, polypropylene, carnauba wax, sazol wax and the like are used alone or in combination of two or more. In general, it is preferably used at a ratio of 1 to 8 parts by weight with respect to 100 parts by weight of the binder resin.

  Also, the above-mentioned fluidizing agent can be a known one that has been generally used conventionally, for example, inorganic fine particles such as silica, titanium oxide, aluminum oxide, acrylic resin, styrene resin, silicon resin, Resin fine particles such as a fluororesin can be used, and it is particularly preferable to use one that has been hydrophobized with a silane coupling agent, a titanium coupling agent, silicon oil, or the like. Such a fluidizing agent is added at a ratio of 0.1 to 3 parts by weight with respect to 100 parts by weight of the toner.

(5) Examples and Comparative Examples <Toner Charged Film>
The following films A to G were prepared as toner charging films.
The surface resistivity of each film was measured with an applied voltage of 100 V using a measuring device Hiresta manufactured by Mitsubishi Chemical Corporation.
The surface roughness of the film was measured using an atomic force microscope Nanoscope IIIa / Dimension 3100 manufactured by Bico.

<Film A>
Addition of 15 parts by weight of 15% solids carbon black (CB) dispersion (ie, CB content is 7.5 parts by weight) and 3 parts by weight of silica having a particle size of 5 μm to 100 parts by weight of urethane emulsion with 30% solids After mixing, the mixture was applied on a PET (polyethylene terephthalate) film and dried at 120 ° C. for 1 hour. The thickness of the coating layer after drying was 30 μm, and this was peeled from the PET film to obtain film A.

<Film B>
To 100 parts by weight of a 30% solids urethane emulsion, 10 parts by weight of a 15% solids carbon black (CB) dispersion (that is, 5 parts by weight of CB) is added, and after mixing, applied onto a PET film, It dried at 120 degreeC for 1 hour. The thickness of the coating layer after drying was 30 μm, and this was peeled off from the PET film to obtain film B.

<Film C>
The same film as film A except that the content of silica as a roughness adjusting agent is 13 parts by weight.

<Film D>
5 parts by weight of sodium perchlorate, an ionic conductive agent, and 4 parts by weight of a carbon black dispersion with a solid content of 15% (ie, CB content is 2 parts by weight) are added to 100 parts by weight of a urethane emulsion with a solid content of 30%. After mixing, it was applied onto a PET film and dried at 120 ° C. for 1 hour. The thickness of the coating layer after drying was 30 μm, and this was peeled from the PET film to obtain a film D.

<Film E>
The same as film A except that the amount of carbon black dispersion with a solid content of 15% was 10 parts by weight (ie, the CB content was 5 parts by weight) and the amount of silica with a particle size of 5 μm was 15 parts by weight.

<Film F>
The same as film D, except that the amount of carbon black dispersion with a solid content of 15% was 2 parts by weight (ie, the CB content was 1 part by weight).
<Film G>
The same as film A except that the content of silica as a roughness modifier is 30 parts by weight.

The above films A to G are summarized in the following table.

Perchloric acid Carbon Silica Surface resistivity Surface roughness
Sodium Black Content (wt.%) Content (wt.%) Particle size Content (Ω / □) Ra (μm)
Film A-7.5 5 μm 3 wt.% 1 × 10 ⁸ 0.5
Film B-5--2 × 10 ⁸ 0.01
Film C-7.5 5 μm 13 wt.% 5 × 10 ⁸ 2
Film D 5 2 − − 1 × 10 ⁷ 0.01
Film E-5 5μm 15wt.% 1 × 10 ⁹ 2
Film F 5 1 − − 1 × 10 ⁸ 0.007
Film G-7.5 5μm 30wt.% 7 × 10 ⁸ 2.5

Regarding the toner carrier, the following A and B were produced as roller-type toner carriers.
<Toner carrier A>
A mold was placed around a core metal having a diameter of 8 mm subjected to easy adhesion treatment, and a liquid silicone rubber whose conductivity was adjusted with carbon black was poured into the mold and vulcanized at 130 ° C. for 2 hours to be molded. At this time, the rubber hardness was 30 degrees and the rubber thickness was 4 mm.

Next, this silicone rubber roller is corona-treated, treated with a silane coupling agent, and then a urethane resin coating solution containing silica fine particles having a particle diameter of 5 μm as a roughness adjusting agent and carbon black as a conductive agent is applied to the outer periphery of the rubber layer. Was applied to form a surface layer. The film thickness of the surface layer was 15 μm. When the surface resistivity was measured using Hiresta manufactured by Mitsubishi Chemical Corporation, it was 1 × 10 ⁹ Ω / □. When the total resistance was measured by the apparatus shown in FIG. 5, it was 2 × 10 ⁶ Ω. Moreover, arithmetic mean roughness Ra (measured with Surfcom 550 manufactured by Tokyo Seimitsu Co., Ltd.) of the surface of the surface layer was 1.2 μm.

<Toner carrier B>
Silica fine particles having a particle diameter of 10 μm were used as a roughness adjusting agent. The rest is the same as toner carrier A.
When the surface resistivity, total resistance, and arithmetic average roughness Ra of the surface of the surface layer were measured in the same manner as in the case of the toner carrier A, the surface resistivity was 4 × 10 ⁹ Ω / □, the total resistance was 2 × 10 ⁶ Ω, The arithmetic average roughness Ra was 2.8 μm.

  The above toner charging film and toner carrier were set in a black toner cartridge in a printer LP-1500C manufactured by Seiko Epson Corporation, and a halftone image was printed and evaluated. This is described below.

<Example 1>
Toner charging film A and toner carrier A were used. The film A was fixed to the fixed electrode so that the film A was in contact with the toner carrier A on the downstream side of the regulating member and on the upstream side of the developing region in the toner carrier surface movement direction. A distance L (see FIG. 2) from the electrode to the nip N between the film and the toner carrying member was 10 mm, and voltage was applied so that the potential difference between the toner carrying member and the toner charging film was 600V. When a halftone image was printed in this state, a good image with no unevenness was obtained. Further, the same image was printed on 5000 sheets, but no particular problem occurred.

<Example 2>
Film B was used as the toner charging film. Other than that is the same as Example 1. When a halftone image was printed, a good image with no unevenness was obtained. Further, the same image was printed on 5000 sheets, but no particular problem occurred.

<Example 3>
Toner charging film C and toner carrier B were used. Other than that is the same as Example 1. When a halftone image was printed, a good image with no unevenness was obtained. Further, the same image was printed on 5000 sheets, but no particular problem occurred.

<Comparative Example 1> (Film surface roughness> Toner carrier surface roughness)
The carrier A was used as the toner carrier. Other than that is the same as Example 3. When the halftone image was printed, vertical stripe-like density unevenness was observed. When the nip portion was observed, the toner was accumulated on the surface of the toner charging film.

<Example 4>
Film D was used as a toner charging member. Other than that is the same as Example 1. When a halftone image was printed, a good image with no unevenness was obtained. Further, the same image was printed on 5000 sheets, but no particular problem occurred.

<Example 5>
Film E was used as a toner charging member. Other than that is the same as Example 3. When a halftone image was printed, a good image with no unevenness was obtained. Further, the same image was printed on 5000 sheets, but no particular problem occurred.

<Comparative example 2>
Film F was used as a toner charging member. Other than that is the same as Example 1. When a halftone image was printed, horizontal stripe-like density unevenness and spotted density unevenness were observed. When the charge amount of the toner on the toner carrier after passing through the toner charging member was measured, it was 15 μC / g and the toner was not sufficiently charged.

<Comparative Example 3>
The film G was used as a toner charging member, and the carrier B was used as a toner carrier. When a halftone image was printed, a good image with no unevenness was obtained. However, when a 5000 sheet print test was performed, vertical stripe-like density unevenness appeared in the image. When the toner charging film was observed, some cracks were observed.

  The present invention can be used to develop an electrostatic latent image formed on an electrostatic latent image carrier in an image forming apparatus such as a copying machine or a printer with a one-component developer.

1 is a diagram illustrating an outline of a configuration of an example of a developing device according to the present invention. FIG. 4 is a plan view of a toner charging member. FIG. 3 is a cross-sectional view of an example of a roller type toner carrier. 3 is a cross-sectional view of an example of a belt-type toner carrier. FIG. It is a figure which shows the method of measuring the whole resistance of a toner carrier.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Single component developing device 11 Electrostatic latent image carrier 12 Roller type toner carrier 13 Agitator 14 Toner supply roller 15 Toner regulating member 16 Developing bias power source 17 Toner charging member 18 Power source 19 Developing device case 19a Toner storage chamber 19b Toner supply chamber 190 Partition Wall 191 Opening 20 Fixed Electrode D Development Area N Nip Part 21 Core Bar 22 Base Layer 23 Surface Layer 30 Belt Type Toner Carrier 31 Base Layer 32 Surface Layer

Claims (4)

  The toner is held on the surface of the toner carrier and transported to the development area, and the amount of toner transported to the development area during the transportation is regulated by a regulating member, and the toner is statically removed from the toner carrier in the development area. A one-component developing device that supplies an electrostatic latent image portion formed on an electrostatic latent image carrier to develop the electrostatic latent image, and is downstream of the regulating member in the moving direction of the toner carrier surface and a development region A one-component developing device comprising a toner charging member arranged in contact with a toner carrier on the upstream side, wherein the toner charging member is a polymer film supported by a fixed electrode.   2. The one-component developing device according to claim 1, wherein the arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier is 0.01 μm to 2 μm.   3. The one-component developing device according to claim 1, wherein the arithmetic average roughness Ra of the surface of the polymer film facing the toner carrier is smaller than the arithmetic average roughness Ra of the toner carrier surface.   4. The one-component developing device according to claim 1, wherein the polymer film contains a roughness adjusting agent in a ratio of 2 to 20 parts by weight with respect to the resin solid content.