JP2008145885A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a high quality image in which the generation of image defects such as white stripes and uneven image and the generation of filming are extremely reduced and high and uniform image density is maintained by preventing the fusion of toner to a layer thickness regulating blade in a non-magnetic one-component developing device. <P>SOLUTION: In the developing device 1 comprising a developer tank 5, a developing roller 6, a feed roller 7, an agitation member 8, and a layer thickness regulating member 9 provided with a layer thickness regulating blade 10 and using an one-component developer 3; the surface hardness of the developing roller 6 is set to 55 to 60° (JIS-A hardness) and the abutting pressure of the layer thickness regulating blade 10 on the developing roller 6 is set to 0.290 to 0.985 N/cm in linear pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device.

  2. Description of the Related Art Image forming apparatuses that use an electrophotographic system (hereinafter simply referred to as “image forming apparatuses”) can print high-quality images on a recording medium with a simple operation, and are now widely used in many fields. The image forming apparatus includes, for example, a photoconductor, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. The photoreceptor has a photosensitive film on its surface. The charging means charges the surface of the photoreceptor to a predetermined polarity and potential. The exposure means forms an electrostatic latent image on the charged photoreceptor surface. The developing means develops the electrostatic latent image on the surface of the photoreceptor with toner to form a toner image. The transfer unit transfers the toner image on the surface of the photoreceptor onto the recording medium. The fixing unit fixes the toner image on the recording medium. Through the processing by these means, an image according to the image information is formed on the recording medium.

  As the developing means, a developing device including a developer carrying member, a layer thickness regulating blade, and a developing tank is widely used. The developer carrying member carries a developer layer on its surface and rotates around its axis, and supplies toner to the electrostatic latent image on the surface of the photoreceptor to form a toner image. The layer thickness regulating blade is a plate-like member extending in parallel with the developer carrying member, and is provided so that one end in the short direction abuts on the surface of the developer carrying member or is separated with a slight gap. The layer thickness regulating blade regulates the layer thickness of the developer layer on the surface of the developer carrying member, and charges the developer at the contact portion with the developer carrying member. The developing tank accommodates the developer carrying member and the layer thickness regulating blade in its internal space and rotates, and accommodates the developer. Developers include a one-component developer containing only toner and a two-component developer containing toner and carrier. When a one-component developer is used, the layer thickness regulating blade is provided so that one end thereof is in contact with the surface of the developer carrying member. A type of developing device that uses a one-component developer and abuts the developer carrier and the layer thickness regulating blade is generally called a non-magnetic one-component developing device.

  In the non-magnetic one-component developing device, the photosensitive member and the developer carrying member are arranged so as to contact each other, and the developer layer on the surface of the developer carrying member is brought into contact with the electrostatic latent image on the surface of the photoreceptor. Toner is supplied to the electrostatic latent image to form a toner image. One of the problems to be solved by the non-magnetic one-component developing device is generation of frictional heat at a contact portion between the developer carrying member and the layer thickness regulating blade. This frictional heat melts the toner, which is a fine granular material mainly composed of a thermoplastic resin such as polyester. The melted toner is deposited by fusing and solidifying on the surface of the layer thickness regulating blade to form a groove on the surface of the developer layer. In the groove portion, the developer does not contact the electrostatic latent image or the contact amount of the developer is small, so that the developer is not sufficiently supplied to the electrostatic latent image. In the image formed by fixing the toner image formed in this way on the recording medium, an image defect called white streak that is a streaky blank portion occurs. The melted toner adheres to the surface of the photoconductor in the form of a film, which may reduce the charging performance of the photoconductor and shorten the useful life of the photoconductor. This phenomenon is called filming. In addition, there is a case where the image density of the image is partially reduced and image unevenness in which the image density becomes non-uniform.

  Conventionally, various proposals have been made to prevent the occurrence of white streaks due to the fusion of toner to the layer thickness regulating blade. For example, a developing device including a developing roller (developer carrier), a charging blade (layer thickness regulating blade), and a heat radiating member that radiates frictional heat held by the charging blade is proposed (for example, Patent Document 1). reference). However, since the heat dissipating member in Patent Document 1 is provided inside the developing tank, the heat dissipating effect is not sufficient. Therefore, it is not possible to significantly reduce the fusion of toner to the charging blade. Another problem is that the frictional heat of the charging blade is conducted to other parts inside the developing tank, so that the toner stored in the developing tank becomes non-uniformly charged.

  On the other hand, conventionally, the surface hardness and surface roughness of the developer carrying member, the contact pressure of the layer thickness regulating blade against the developer carrying member, the elastic modulus (Young's modulus) of the layer thickness regulating blade, etc. have been appropriately adjusted. ing. For example, the layer thickness of the toner layer (developer layer) carried on the surface of the developing roller (developer carrier) is set to 1 to 2 times the volume center particle diameter of the toner, and the surface roughness of the developing roller is arithmetic average roughness A nonmagnetic one-component developing device having a thickness (Ra) of 0.5 to 1.5 μm is proposed (see, for example, Patent Document 2). In the technique of Patent Document 2, a replenishing roller for replenishing toner to the developing roller is provided so as to contact the developing roller, the Asker C hardness of the developing roller surface is adjusted to 65 to 75 °, and an elastic body regulating blade ( The contact pressure of the layer thickness regulating blade) to the developing roller is adjusted to 0.1 to 0.6 kg / mm (linear pressure). As a result, the layer thickness of the toner layer falls within the above range. However, Patent Document 2 relates to a technique for configuring an image forming apparatus without providing a cleaning unit for removing toner remaining on the surface of a photoreceptor after a toner image is transferred to a recording medium. Is not intended to prevent.

JP-A-7-248673 JP 2000-338776 A

  An object of the present invention is a non-magnetic one-component developing device which prevents toner from fusing to a layer thickness regulating blade, and has very few image defects such as white streaks and image unevenness and filming. It is an object of the present invention to provide a developing device that can contribute to the formation of a high-density image having a high density and a uniform density.

The present invention provides a developer carrier for carrying a non-magnetic one-component developer layer on the surface and supplying a non-magnetic one-component developer to a latent image carrier, and a developer carrier provided in contact with the developer carrier. In a developing device including a layer thickness regulating blade that regulates the layer thickness of the non-magnetic one-component developer layer on the agent carrier,
The surface hardness of the developer carrying member is 55 to 60 ° (55 ° or more and 60 ° or less) in JIS-A hardness, and the contact pressure of the layer thickness regulating blade to the developer carrying member is 0.290 in terms of linear pressure. The developing device is characterized in that it is ˜0.985 N / cm (0.290 N / cm or more and 0.985 N / cm or less).

  In the developing device of the present invention, the ten-point average height Rz of the developer carrying member is 10 to 20 μm (10 μm or more and 20 μm or less).

Further, in the developing device of the present invention, the volume resistance value of the developer carrying member is 1 × 10 ^{3 to} 5 × 10 ⁷ Ω · cm (1 × 10 ³ Ω · cm or more, 5 × 10 ⁷ Ω · cm or less). It is characterized by that.

  Further, in the developing device of the present invention, the developer carrying member includes a metal shaft body, a urethane rubber layer having a thickness of 1 to 6 mm (1 mm or more and 6 mm or less) provided on the surface of the metal shaft body, and a urethane rubber layer. And an acrylic resin layer having a thickness of 1 to 10 μm (1 μm or more and 10 μm or less) provided on the surface.

  Furthermore, the developing device of the present invention is characterized in that the layer thickness regulating blade is made of stainless steel and has a thickness of 50 to 200 μm (5 μm or more and 200 μm or less).

Furthermore, the developing device of the present invention is characterized in that the Young's modulus of the layer thickness regulating blade is 5 × 10 ^{10 to} 3 × 10 ¹¹ Pa (5 × 10 ¹⁰ Pa or more and 3 × 10 ¹¹ Pa or less).

  According to the present invention, there is provided a non-magnetic one-component developing device including a developer carrying member and a layer thickness regulating blade, wherein the developer carrying member has a surface hardness of 55 to 60 degrees as JIS-A hardness and a layer thickness. By setting the contact pressure of the regulating blade to the developer carrying body as a linear pressure of 0.290 to 0.985 N / cm, the developer carrying body and the contact portion between the developer carrying body and the layer thickness regulating blade Lubricity with the layer thickness regulating blade is increased, and heat generation due to friction between both is remarkably reduced. As a result, the temperature rise at the contact portion between the developer carrier and the layer thickness regulating blade and in the vicinity thereof is reduced, and fusion, solidification, and deposition of the molten toner on the layer thickness regulating blade accompanying the melting of the toner are extremely difficult. Less. Therefore, if the developing device of the present invention is incorporated in an electrophotographic image forming apparatus, the toner can be sufficiently prevented from being fused to the layer thickness regulating blade, and white streaks that can be visually recognized cannot be seen. However, white streak that deteriorates the quality of the entire image does not occur. In addition, other image defects such as image unevenness and filming do not occur. That is, by using the developing device of the present invention, a high-quality and high-quality image with a high image density can be formed stably and for a long time.

  According to the present invention, it is preferable that the surface roughness of the developer carrying member is 10 to 20 μm as the ten-point average height Rz. As a result, the lubricity between the developer carrier and the layer thickness regulating blade is further increased, the heat generated by the friction between the two is further reduced, and the temperature rise is further reduced. As a result, image defects such as white streaks associated with fusion, solidification and deposition of the molten toner on the layer thickness regulating blade are almost eliminated. Further, the occurrence of image unevenness is remarkably suppressed.

According to the present invention, the development conditions can be controlled by setting the volume resistance value of the developer carrier to a range of 1 × 10 ^{3 to} 5 × 10 ⁷ Ω · cm. That is, since it is easy to control the development density within an appropriate range, image defects such as a reduction in image density do not occur.

  According to the present invention, as a developer carrier, a developer carrier in which a metal shaft, a urethane rubber layer having a thickness of 1 to 6 mm, and an acrylic resin layer having a thickness of 1 to 10 μm are laminated in this order. preferable. By using the developer carrying member having such a configuration, the lubricating performance of the developer carrying member and the contact portion between the layer thickness regulating blades can be further enhanced. In addition, if the developer carrying member having the above-described configuration is used, even if the material constituting the layer thickness regulating blade is changed, there is little fluctuation in the lubrication performance of both, and a high level of lubrication performance is stably exhibited. The Accordingly, the degree of freedom in selecting the material for the layer thickness regulating blade is increased, and as a result, the degree of freedom in designing the entire developing device is increased.

  According to the present invention, by using a layer thickness regulating blade made of stainless steel and having a thickness of 50 to 200 μm, the lubricating performance of both at the contact portion with the developer carrier is further improved. In particular, when used in combination with a developer bearing member in which the metal shaft, urethane rubber layer, and acrylic resin layer are laminated in this order, the lubricating performance is particularly improved, and the amount of heat generated by friction between the two is minimized. Become.

According to the present invention, by adjusting the elastic modulus of the layer thickness regulating blade as a Young's modulus in the range of 5 × 10 ^{10 to} 3 × 10 ¹¹ Pa, the contact portion between the developer carrier and the layer thickness regulating blade The lubrication performance of both can be further improved. At the same time, the amount of film loss of the photosensitive film for forming an electrostatic latent image formed on the surface of the photoreceptor can be reduced, so that there is an advantage that the life of the photoreceptor can be extended.

  FIG. 1 is a cross-sectional view schematically showing a configuration of a developing device 1 according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a configuration of a main part of the developing device 1 shown in FIG. The developing device 1 is a non-magnetic one-component developing device including a developing tank 5, a developing roller 6 that is a developer carrier, a supply roller 7, a stirring member 8, and a layer thickness regulating member 9. The developing device 1 is mounted such that the developing roller 6 contacts the surface of the photosensitive drum 2 in an electrophotographic image forming apparatus (not shown). A contact portion between the photosensitive drum 2 and the developing roller 6 is a developing nip portion. The developing device 1 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 2 and develops it to form a toner image.

  The developing tank 5 is a container-like member having an internal space, and stores the developer in the internal space. Developer 3 is a one-component developer containing toner. The developing tank 5 accommodates the developing roller 6, the supply roller 7, and the stirring member 8 so as to rotatably support each of them and to support the layer thickness regulating member 9. An opening 5a is formed on the side surface of the developing tank 5 facing the photosensitive drum 2. A part of the developing roller 6 protrudes toward the outside of the developing tank 5 from the opening 5 a and comes into contact with the photosensitive drum 2. A toner cartridge and a toner hopper (not shown) are provided above the developing tank wall in the vertical direction. More specifically, the toner cartridge, the toner hopper, and the developing tank 5 are provided in this order from the upper side to the lower side in the vertical direction. The toner cartridge is a cylindrical container member that stores toner in an internal space, and is detachably attached to an image forming apparatus main body (not shown) to which the developing device 1 is mounted. Further, the toner cartridge is rotationally driven around the axis by a driving unit (not shown) provided in the image forming apparatus. An elongated opening extending in the longitudinal direction is formed on the side surface in the longitudinal direction of the toner cartridge, and the toner falls from the elongated opening and is supplied to the toner hopper as the toner cartridge rotates. The rotation of the toner cartridge is controlled according to the toner consumption status by a control unit (not shown) provided in the image forming apparatus. The toner hopper is provided, for example, such that a toner replenishing port that is an opening formed in the vertical bottom surface thereof communicates with a toner receiving port that is an opening formed in the vertical top surface of the developing tank 5 in the vertical direction. The toner hopper replenishes the developing tank 5 with toner supplied from the toner cartridge. The developing tank 5 is formed of, for example, a synthetic resin, preferably an injection-moldable thermoplastic resin.

  The developing roller 6 is a roller member provided so as to be rotatable around an axis by a driving unit (not shown). The developing roller 6 is disposed in the vicinity of the opening 2 a of the developing tank 5 so as to face the photosensitive drum 2 and to be in contact with the photosensitive drum 2. The developing roller 6 carries a developer layer (not shown) on its surface and is driven to rotate. In the developing nip portion, toner is supplied to the electrostatic latent image on the surface of the photosensitive drum 2 and developed to form a toner image. When supplying toner from the developing roller 6 to the electrostatic latent image on the photosensitive drum 2, a developing bias voltage is applied to the developing roller 6 from a power source (not shown) connected to the developing roller 6.

  Further, the surface hardness of the developing roller 6 is 55 to 60 degrees in terms of JIS-A hardness. When the JIS-A hardness is less than 55 °, the lubricity between the developing roller 6 and the layer thickness regulating blade 10 decreases at the contact portion between the developing roller 6 and the layer thickness regulating blade 10 described later, and frictional heat is generated. There is a possibility that the toner becomes large and melts, and the toner is fixed and deposited on the layer thickness regulating blade 10. When the JIS-A hardness exceeds 60 °, the lubricity itself is not particularly affected, but the photosensitive film (resin layer for forming an electrostatic latent image) (not shown) formed on the surface of the photosensitive drum 2 is not affected. There is a risk that the amount of film loss increases and the durability of the photosensitive drum 2 is reduced. In this specification, JIS-A hardness was measured according to JIS K 6253 using an A-type hardness meter (trade name: HH-331, manufactured by Mitutoyo Corporation).

  Further, the developing roller 6 preferably has a surface roughness of 10 to 20 μm as a ten-point average height Rz. If the ten-point average height Rz is less than 10 μm, the lubricity of the developing roller 6 and the layer thickness regulating blade 10 at the abutting portion may be reduced, and heat generation due to friction may increase. When the ten-point average height Rz exceeds 20 μm, the image density in the finally formed image becomes non-uniform and image unevenness may occur. In this specification, the ten-point average height Rz is 2.5 mm as a measurement length based on “JIS B 0601 (1994)”, and the center line of the extracted portion is taken as the X axis and the vertical magnification. The value when the direction is expressed by the Y axis is expressed in micrometers (μm), and the product name: Surfcorder SE-3400 manufactured by Kosaka Laboratory Co., Ltd. was used for the surface roughness measuring instrument.

Further, the developing roller 6 preferably has a volume resistance value of 1 × 10 ^{3 to} 5 × 10 ⁷ Ω · m. When the volume resistance value is less than 1 × 10 ³ Ω · m, the resistance becomes too low, the image density becomes too high, and the image quality itself may become hard. On the other hand, if the volume resistance value exceeds 5 × 10 ⁷ Ω · m, the resistance becomes too high, the image density becomes too low, and the image quality itself may be soft. In this specification, the volume resistance value is determined by applying a DC voltage of 500 V between the shaft and the metal drum in a state where the developing roller 6 is brought into contact with the cylindrical metal drum and rotated, and in series with the metal drum. The voltage applied to the resistor connected to was measured, the contact width with the drum was determined in advance, and the resistance value obtained using this contact area was converted to the volume resistance value.

  As the developing roller 6, for example, a roller-shaped member including a metal shaft, an elastic layer provided on the surface of the metal shaft, and a surface layer provided on the surface of the elastic layer can be used. A metal shaft body is a shaft body formed from metal materials, such as stainless steel, iron, aluminum, for example. The elastic layer is formed of a rubber material having elasticity. As the rubber material having elasticity, urethane rubber is preferable. The thickness of the elastic layer is preferably 1 to 6 mm. If it is less than 1 mm, the elasticity of the developing roller 6 is insufficient, and the surface of the photosensitive drum 2 may be damaged, and the durability of the photosensitive drum 2 may be reduced. If it exceeds 6 mm, the surface hardness of the developing roller 6 becomes lower than the above-mentioned range, and there is a possibility that heat generation due to friction at the contact portion between the developing roller 6 and the layer thickness regulating blade 10 becomes large. The surface layer is formed of a synthetic resin having high hardness. As the resin material having high hardness, an acrylic resin is preferable. The thickness of the surface layer is preferably 1 to 10 μm. If it is less than 1 μm, the surface hardness of the developing roller 6 becomes lower than the range specified above, and the same problem as described above may occur. If the thickness exceeds 10 μm, the surface hardness of the developing roller 6 becomes too high, and there is a possibility that the amount of reduction of the photosensitive film on the photosensitive drum 2 increases and the service life of the photosensitive drum 2 decreases accordingly. In the present embodiment, a roller-shaped member including an iron shaft having a diameter of 10 mm, a urethane rubber layer having a thickness of 3 mm, and an acrylic resin layer having a thickness of 0.5 μm is used.

  The supply roller 7 is a roller member provided so as to face the photosensitive drum 2 with the developing roller 6 interposed therebetween. The supply roller 7 is provided so as to be separated from the developing roller 6 with a slight gap. The supply roller 7 is provided so as to be rotationally driven around an axis by a driving means (not shown). The supply roller 7 charges the developer 3 accommodated in the internal space of the developing tank 5 by its rotational drive, and conveys the developer 3 to the periphery of the developing roller 6. The agitating member 8 is a rotating member that is provided so as to face the developing roller 6 with the supply roller 7 interposed therebetween, and is driven to rotate about an axis by a driving unit (not shown). The stirring member 8 uniformly mixes and supplies the developer 3 accommodated in the developing tank 5 and the developer 3 newly supplied into the developing tank 5 from a toner cartridge (not shown) via a toner hopper (not shown). It is conveyed around the roller 7.

  The layer thickness regulating member 9 includes a layer thickness regulating blade 10 and a support member 11. The layer thickness regulating blade 10 is a plate-like member provided so that one end in the short direction is supported by the support member 11 and the other end is in contact with the surface of the developing roller 6. The tip of the other end of the layer thickness regulating blade 10 that contacts the surface of the developing roller 6 is bent outwardly in the radial direction of the developing roller 6 from the other end that contacts the surface of the developing roller 6 in the tangential direction. Is provided.

The elastic modulus of the layer thickness regulating blade 10 is preferably 5 × 10 ^{10 to} 3 × 10 ¹¹ Pa as Young's modulus (tensile elastic modulus). If it is less than 5 × 10 ¹⁰ Pa, it is difficult to adjust the contact pressure of the layer thickness regulating blade 10 against the developing roller 6 to an appropriate range, and the layer thickness of the developer layer on the surface of the developing roller 6 may not be sufficiently regulated. There is. On the other hand, if it exceeds 3 × 10 ¹¹ Pa, the surface of the developing roller 6 may be damaged. In this specification, the Young's modulus is determined by performing a tensile test using a 25 × 250 mm strip test piece in accordance with JIS K 7127, drawing a tangent line to the curve of the initial strain region of the obtained stress / strain curve, and its inclination. Required by Although there is no restriction | limiting in particular as an elastic material for forming the layer thickness control blade 10, For example, a metal, a synthetic resin, rubber | gum etc. are mentioned. Among these, metal is preferable in consideration of appropriately improving the lubricity of the developing roller 6 and the layer thickness regulating blade 10 at the contact portion. Of the metals, stainless steel is preferred. The thickness of the layer thickness regulating blade 10 is preferably 50 to 200 μm. If it is less than 50 μm, the thickness of the developer layer on the surface of the developing roller 6 may not be sufficiently regulated. If it exceeds 200 μm, the layer thickness regulating blade 10 may damage the surface of the developing roller 6. The contact pressure of the layer thickness regulating blade 10 against the surface of the developing roller 6 is 0.290 to 0.985 N / cm. If it is less than 0.290 N / cm, the layer thickness regulation of the developer layer on the surface of the developing roller 6 may be insufficient. If it exceeds 0.985 N / cm, the lubricity of the developing roller 6 and the layer thickness regulating blade 10 at the contact portion may be reduced, and heat generation due to friction may increase.

  The support member 11 is a plate-like member that supports one end of the layer thickness regulating blade 10 in the short direction, and the support member 11 itself is supported by the developing tank 5. Examples of the material for forming the support member 11 include synthetic resins and metal materials.

  According to the developing device 1, the developer 3 accommodated in the internal space of the developing tank 5 is uniformly mixed by the stirring member 8 and fed to the periphery of the supply roller 7. The supply roller 7 charges the developer 3 by its rotation and feeds the charged developer 3 to the periphery of the developing roller 6. The developing roller 6 rotates on its surface with the charged developer 3 to form a developer layer, and the layer thickness of the developer layer is made uniform at the contact portion with the layer thickness regulating blade 10. The The developing roller 6 carries a developer layer having a uniform layer thickness and further rotates, and supplies the developer 3 to the electrostatic latent image on the surface of the photosensitive drum 2 at the developing nip portion to form a toner image. The developing roller 6 further rotates and replenishes the surface with the developer 3. This toner image forming operation is repeatedly executed.

  The developing device 1 is used in various electrophotographic image forming apparatuses including a photosensitive drum 2 for forming a toner image. Here, the photosensitive drum 2 is rotatably supported by a support member (not shown), is rotatably provided around an axis by a drive means (not shown), and a photosensitive drum on which an electrostatic latent image and thus a toner image is formed. A roller-shaped member having a film. For the photosensitive drum 2, for example, a roller-shaped member including a conductive base (not shown) and a photosensitive film (not shown) formed on the surface of the conductive base can be used. Examples of the photosensitive film include an organic photosensitive film and an inorganic photosensitive film. As an organic photosensitive film, a laminate of a charge generation layer, which is a resin layer containing a charge generation material, and a charge transport layer, which is a resin layer containing a charge transport material, a charge generation material and a charge transport material in one resin layer And a resin layer containing. Examples of the inorganic photosensitive film include films containing one or more selected from zinc oxide, selenium, amorphous silicon and the like. A base film may be interposed between the conductive substrate and the photosensitive film, and a surface film (protective film) for mainly protecting the photosensitive film may be provided on the surface of the photosensitive film.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.
(Examples 1-4 and Comparative Examples 1-6)
In the laser printer (trade name: AR-C150, manufactured by Sharp Corporation), the developing device was modified for non-magnetic one-component development, and the surface hardness (°) and Rz (ten-point average height) shown in Table 2 for the developing roller , Μm), and a contact pressure against the developing roller of a stainless steel layer thickness regulating blade (thickness: 100 μm, Young's modulus: 2.06 × 10 ¹¹ Pa) (in Table 2, simply “ The image forming apparatus of Examples 1 to 4 and Comparative Examples 1 to 6 equipped with the developing device of the present invention was manufactured. The construction and materials of the developing rollers in Examples 1 to 4 and Comparative Examples 1 to 6 are as shown in Table 1.

Using the image forming apparatuses of Examples 1 to 4 and Comparative Examples 1 to 6, a test image including a solid image portion is undetermined by adjusting the toner adhesion amount to 0.6 mg / cm ² on A4 plain paper. It was formed in the state of wearing. The formed unfixed image was fixed on A4 plain paper by an external fixing machine, and the obtained fixed image was used as an evaluation image. As the external fixing device, a fixing device obtained by modifying a commercially available image forming apparatus (trade name: Digital Full Color Multifunction Device AR-150, manufactured by Sharp Corporation) was used.

[Thickness of developer layer]
The layer thickness of the developer layer on the surface of the developing roller (simply indicated as “layer thickness” in Table 2) was determined as follows as the toner weight value (mg / cm ² ) per unit area. The developer on the developer carrying member that has passed through the layer thickness regulating blade is scraped off, and its weight is measured. The weight (mg) was determined by dividing by the surface area (cm ² ) of the part where the developer was scraped off. The results are shown in Table 2.

[White lines and image irregularities]
Using the image forming apparatuses of Examples 1 to 4 and Comparative Examples 1 to 6, after printing 10,000 test images in the same manner as described above, 100 test images were further printed in the same manner. About 100 test images, the occurrence of white streaks and image unevenness was visually determined. A case where no white streak or image unevenness was observed was judged as “◯”, and a case where even a single test image showed white streak or image unevenness was judged as “x”.

[Filming]
Using the image forming apparatuses of Examples 1 to 4 and Comparative Examples 1 to 6, after printing 10,000 test images in the same manner as described above, this corresponds to the length of the developing roller and the photosensitive drum that are actually used in the longitudinal direction. A solid image was output, and the obtained solid image was visually observed to determine whether filming marks were generated on the solid image. Also, the surface of the photosensitive drum is observed with an electron microscope, combined with the result of visual observation of the solid image, the presence or absence of toner filming on the surface of the photosensitive member is checked, and both the solid image is visually observed and the electron microscope is observed. The case where the occurrence of filming was not recognized was evaluated as “◯”, and the case where the occurrence of filming was observed in any one of the solid image observation and the electron microscope was evaluated as “x”.

[Image density]
About the obtained image for evaluation, the optical density of 20 places of the solid image part was measured using the spectrocolorimetric densitometer (trade name: X-Rite 938, manufactured by Nihon Kiseki Printing Co., Ltd.). The average value of the measured optical densities was used as an evaluation index for image density, and those having an optical density of 1.2 or more were evaluated as “◯” and those having an optical density of less than 1.2 were evaluated as “x”.

[Comprehensive evaluation]
All of the evaluations of the above test items were evaluated as “◯”, and at least one of the above test items was evaluated as “×”.

  From Table 2, it is clear that by using the developing device of the present invention, image defects such as white streaks and image unevenness and filming can be prevented, and an image having a high image density can be stably formed.

1 is a cross-sectional view schematically showing a configuration of a developing device according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view illustrating a configuration of a main part of the developing device illustrated in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing device 2 Photoconductor drum 3 Developer 5 Developing tank 6 Developing roller 7 Supply roller 8 Stirring member 9 Layer thickness regulating member 10 Layer thickness regulating blade 11 Support member

Claims (6)

A developer carrier that carries a nonmagnetic one-component developer layer on the surface and supplies the nonmagnetic one-component developer to the latent image carrier, and a developer carrier that is provided in contact with the developer carrier and on the developer carrier A developing device including a layer thickness regulating blade that regulates the layer thickness of the non-magnetic one-component developer layer of
The surface hardness of the developer carrying member is 55 to 60 ° in terms of JIS-A hardness, and the contact pressure of the layer thickness regulating blade to the developer carrying member is 0.290 to 0.985 N / cm in terms of linear pressure. A developing device.   The developing device according to claim 1, wherein the ten-point average height Rz of the developer carrying member is 10 to 20 μm. ^3. The developing device according to claim 1, wherein a volume resistance value of the developer carrying member is 1 × 10 ^{3 to} 5 × 10 ⁷ Ω · cm.   The developer carrying member includes a metal shaft, a urethane rubber layer having a thickness of 1 to 6 mm provided on the surface of the metal shaft, and an acrylic resin layer having a thickness of 1 to 10 μm provided on the surface of the urethane rubber layer. The developing device according to claim 1, wherein the developing device is included.   The developing device according to claim 1, wherein the layer thickness regulating blade is made of stainless steel and has a thickness of 50 to 200 μm. The developing device according to claim 1, wherein the Young's modulus of the layer thickness regulating blade is 5 × 10 ^{10 to} 3 × 10 ¹¹ Pa.

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