JP2008152099A - Developing device, image forming apparatus, carrier, toner and developer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, wherein a lubricant can be applied onto an image bearing member, at all times and stably regardless of image area ratio and stable high-quality images can be obtained over a long period of time. <P>SOLUTION: The developing device comprises a main unit 4 of the developing device internally provided with a lubricant added developer; a developer bearing member 41 which is disposed in the main unit of the developing device and bears and conveys the developer as a magnetic brush; a supply conveyance passage 44a having a supply conveyance member 44b, which conveys the developer under stirring along the axial direction of the developer bearing member and supplies the developer to the developer bearing member; a recovery conveyance passage 43a having a recovery conveyance member 43b, which recovers developer after development from the developer bearing member and conveys the recovered developer, in the same direction as the supply conveyance member; and a stirring conveyance passage 45a having a stirring conveyance member 45b, which conveys developer under stirring in the opposite direction to the supply conveyance member, through which the developer prepared by stirring surplus developer not supplied to the developer bearing member from the supply conveyance passage and the recovered developer from the recovery conveyance passage is supplied circulated, to the supply conveyance passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, and more specifically, a developing device used in the image forming apparatus, a copier, a printer, a plotter, a facsimile equipped with the developing device, or the like. An image forming apparatus such as a multifunction peripheral, a developer carrier used in the developing apparatus or the image forming apparatus, a developer toner used in the developing apparatus or the image forming apparatus, a developer using the carrier and the toner About.

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, a lubricant (also referred to as a lubricant) is applied to a photoreceptor so as to lower the coefficient of friction of the photoreceptor as an image carrier for the purpose of improving transfer efficiency and improving cleaning properties. The method of applying is performed.
However, in the method in which the lubricant application unit is provided on the photosensitive member, the size of the apparatus is increased and the trouble of replacement work is generated. Therefore, a lubricant is externally added to the developer in response to the downsizing of the image forming apparatus. A method of supplying a lubricant from the developing unit to the photoreceptor has been proposed.

  For example, Patent Document 1 uses an image carrier (photoconductor) in which a protective layer contains a filler, and the filler content in the protective layer is monotonously changed in the longitudinal direction. A developing means for developing the electrostatic latent image formed thereon, wherein the developing means is disposed at least in parallel to the developer carrying body and a developer carrying body arranged opposite to the image carrying body; The first developer conveying member that conveys the developer in the longitudinal direction of the developer carrying member, and the second developer conveying member that conveys the developer in the opposite direction to the first developer conveying member A toner containing at least one of a fixing aid or a lubricant as the toner used in the developing unit, and the image carrier on the upstream side in the transport direction of the first developer transport member. It is characterized in that the filler content in the protective layer is reduced. The image forming apparatus is described.

  Patent Document 2 discloses an image carrier having a protective layer containing particles on the surface and having the thickness of the protective layer monotonously changed in the longitudinal direction, a charging unit, an exposure unit, a developing unit, and a transfer unit. An image forming apparatus having a fixing unit and a cleaning unit, wherein the developing unit includes at least a developer carrying member disposed to face the image carrying member, and a developer carrying member disposed in parallel with the developer carrying member. A first developer conveying member that conveys the developer in the longitudinal direction of the developer carrier, and a second developer conveying member that conveys the developer in the direction opposite to the first developer conveying member, The toner used in the developing means is characterized in that the film thickness of the protective layer of the image carrier on the upstream side in the developer transport direction of the developer transport member is smaller than that on the downstream side. It contains a fixing aid and / or a lubricant. The image forming apparatus is described.

  In Patent Document 3, a latent image carrier formed in a drum shape or a belt shape is continuously or intermittently rotated, and its peripheral surface is cyclically moved in a fixed direction, while recording on the peripheral surface. In a recording apparatus in which an electrostatic latent image corresponding to an image is formed, this electrostatic latent image is dry-developed, and a visible image of the resulting powder is transferred and fixed onto a recording sheet, the cleaning aid is a toner Development is performed using a developer added in an amount of 0.01 to 1.0 wt% with respect to the cleaning agent and the latent image carrier in common contact with the cleaning aid fixed to the stationary member. A cleaning method for a latent image carrier is described in which cleaning is performed while supplying a cleaning aid to the latent image carrier through a rotating cleaning member.

  Patent Document 4 has a cleaning member that develops toner on the surface of an organic photoreceptor provided with a photosensitive layer on a conductive support and cleans the toner remaining on the photoreceptor after transfer to a recording material with an elastic rubber blade. In the electrophotographic image forming apparatus, zinc stearate is contained in the toner in an amount of 0.01% or more and 0.5% or less based on the toner weight, and the elastic rubber blade is fixed to the cleaning member. An electrophotographic image forming apparatus is described in which the supporting member is substantially held on the photosensitive member contact surface side of the cleaning blade.

Japanese Patent No. 3732109 (JP 2002-318461) Japanese Patent Laid-Open No. 2002-341577 Japanese Patent Publication No. 2-55790 Japanese Patent Laid-Open No. 11-184340 JP-A-53-95033 JP-A-53-138229 JP-A-53-133455 JP-A-53-132547 Japanese Patent Laid-Open No. 54-21728 JP 54-12742 A JP 54-22834 A JP 54-17733 A JP 54-2129 A JP 54-17734 A JP-A-57-195767 JP-A-57-195758

The developing devices used in the prior arts such as Patent Document 1 and Patent Document 2 described above are biaxial transport type developing devices including two members for transporting and stirring the developer. Here, FIG. 15 shows a configuration example of a biaxial transport type developing device.
In FIG. 15, this biaxial transport type developing device includes a developer supply and recovery transport member (screw, auger, etc.) 107 and a supply / recovery transport path to the developing roller 103, which is a developer carrier, and toner replenishment. It is composed of a conveying member (screw, auger, etc.) 108 for subsequent conveyance and stirring, and two conveying members 107 and 108 and two conveying paths, and is arranged horizontally below the developing roller 103. Yes.

  When a color image is formed with a conventional biaxial conveying / stirring developing device as shown in FIG. 15 in a system for supplying a lubricant from a developing device to a photoreceptor, a streak-like image defect occurs in the color image over time. There has occurred. As a result of analysis of the image defect position by the present inventors, it has been found that the coefficient of friction of the photoconductor is high at the position in the photoconductor axial direction corresponding to the streak-like image defect occurrence portion. It was also found that there was a transfer failure or cleaning failure due to a decrease in transfer rate at that position. This indicates that the supply of lubricant is insufficient at that portion, and that portion corresponds to the position of the downstream portion of the developer circulating portion of the developing portion in the sleeve of the developing roller 103 facing the photosensitive member. all right. The cause can be considered as follows.

  In a biaxial conveyance type developing device, the developer used for development falls on a conveyance member for supply and recovery (for example, a supply screw) and is immediately used for development. When the image is continuously output, the toner density of the developer decreases as it goes downstream of the supply screw, so that the developer having a reduced toner density is pumped up at the downstream position in the axial direction of the developing sleeve. The development is performed in contact with the photosensitive member. That is, since the lubricant is supplied to the photoconductor in proportion to the toner density, if continuous output of an image with a high image area ratio is performed, uneven application of the lubricant occurs, and the photoconductor portion facing the downstream portion in the development axis direction In this case, the amount of lubricant applied was reduced, resulting in image defects. Therefore, the conventional lubricant coating method using a biaxial transport type developing device has a problem that stable image formation cannot be performed for a long period of time.

  The present invention has been made in view of the above circumstances, and can always stably apply a lubricant to an image carrier (photoreceptor) irrespective of an image area ratio, and can stably provide a high-quality image over a long period of time. In particular, it is an object of the present invention to provide a developing device capable of obtaining a color image and an image forming apparatus provided with the developing device. Another object of the present invention is to provide a carrier, toner, or developer suitable for use in the developing device or the image forming apparatus.

In order to achieve the above object, the present invention adopts the following means.
According to a first aspect of the present invention, there is provided a developing device, a developing device main body having at least a developer composed of toner and a carrier to which a lubricant is added, and a developer provided in the developing device main body. A developer carrying body that carries and conveys the developer as a magnetic brush, and a supply carrying member that stirs and conveys the developer along the axial direction of the developer carrying body and supplies the developer to the developer carrying body A recovery transport path having a recovery transport member that recovers the developer after completion of development from the developer carrier and transports the recovered developer in the same direction as the supply transport member; An agitating and conveying member that agitates and conveys in a direction opposite to the supply and conveying member, and agitates the surplus developer that has not been supplied from the supply and conveying path to the developer carrier and the collected developer from the collecting and conveying path; The developer And to circulate and supply the stirring conveyance path in the sheet conveying path, characterized by comprising a.

According to a second means of the present invention, in the developing device of the first means, the developer carrier comprises a non-magnetic developing sleeve and a magnetic field generating means fixedly disposed in the sleeve. To do.
According to a third means of the present invention, in the developing device of the first or second means, a toner storage portion containing at least unused toner, and a predetermined amount of toner in the toner storage portion are supplied to the main body of the developing device. And a toner replenishing means for transporting the toner to the developing device main body. The lubricant is mixed with unused toner in advance and stored in the toner storage unit, and is supplied to the developing device main body together with the toner by the toner replenishing means. .

According to a fourth means of the present invention, in the developing device of any one of the first to third means, the supply conveyance path and the agitation conveyance path are arranged substantially horizontally, and the recovery conveyance path is It is arrange | positioned above the said supply conveyance path and the said stirring conveyance path, It is characterized by the above-mentioned.
According to a fifth means of the present invention, in the developing device of any one of the first to third means, the recovery conveyance path, the supply conveyance path, and the stirring conveyance path are arranged substantially horizontally. It is characterized by that.
According to a sixth means of the present invention, in the developing device of any one of the third to fifth means, the lubricant is replenished to the developing device main body in the recovery conveyance path by the toner replenishing means. It is characterized by.

A seventh means of the present invention is the developing apparatus of any one of the first to sixth means, wherein the lubricant is a fatty acid metal salt.
According to an eighth means of the present invention, in the developing device of any one of the first to sixth means, the lubricant is a fluorine-containing resin.

According to a ninth means of the present invention, in the developing device of the seventh means, the fatty acid metal salt is zinc stearate.
The tenth means of the present invention is characterized in that, in the developing device of the ninth means, the amount of zinc stearate added is 0.01 to 5% with respect to the toner weight.

According to an eleventh means of the present invention, in the developing device of the eighth means, the fluorine-containing resin is a polytetrafluoroethylene resin.
The twelfth means of the present invention is characterized in that, in the developing device of the eleventh means, the addition amount of the polytetrafluoroethylene resin is 0.01 to 5% with respect to the toner weight. .

  According to a thirteenth aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier that carries an electrostatic latent image; a charging device that charges the image carrier; and a developer that contains the developer. A developing device of any one of the first to twelfth means for developing and developing a toner image, and a transfer means for transferring the toner image on the image carrier directly to a recording material or via an intermediate transfer member And an image is formed on the recording material.

  According to a fourteenth aspect of the present invention, there is provided an image forming apparatus, comprising: an image carrier that carries an electrostatic latent image; a charging device that charges the image carrier; and a developer that contains the developer. A plurality of image forming units each having at least a developing device of any one of the first to twelfth means for developing and developing the toner image into a toner image are provided for each color, and the toner image on the image carrier is recorded. At least transfer means for transferring to the material directly or via an intermediate transfer body, and after forming toner images of each color on the image carrier of the plurality of image forming units, the image is transferred to the recording material by the transfer means. A multicolor or color image is formed on the recording material.

According to a fifteenth aspect of the present invention, in the image forming apparatus of the thirteenth or fourteenth aspect, a charging roller to which an AC voltage is superimposed is used as the charging device.
According to a sixteenth means of the present invention, in the image forming apparatus of the fifteenth means, the charging roller is installed with a certain gap from the image carrier.

According to a seventeenth means of the present invention, in the image forming apparatus according to any one of the thirteenth to sixteenth means, the image carrier contains a filler in a surface layer.
According to an eighteenth means of the present invention, in the image forming apparatus of the seventeenth means, at least one kind of inorganic filler is used as the filler.

  According to a nineteenth aspect of the present invention, there is provided a developer carrier used in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means. The volume average particle size is 20 to 60 μm.

According to a twentieth aspect of the present invention, there is provided a developer toner used in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means. The volume average particle diameter (D4) is 3 to 8 μm, and the ratio (D4 / D1) of the volume average particle diameter (D4) to the number average particle diameter (D1) is in the range of 1.00 to 1.40. It is characterized by being.
The twenty-first means of the present invention is a developer toner used in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means. The shape factor SF-1 is in the range of 100 to 150, and the shape factor SF-2 is in the range of 100 to 150.
Further, a twenty-second means of the present invention is a developer toner used in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means. Further, fine particles having an average primary particle diameter of 50 to 500 nm and a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles.

  A twenty-third means of the present invention is a developer used in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means. The carrier of the above means and the toner of any one of the 20th to 22nd means are used.

  The developing device of the first and second means of the present invention includes a developing device main body provided with a developer composed of toner and a carrier to which at least a lubricant is added, and the developing device main body. A developer carrying body that carries and conveys the magnetic brush as a magnetic brush (consisting of a non-magnetic developing sleeve and a magnetic field generating means fixedly disposed in the sleeve), and development along the axial direction of the developer carrying body The developer is agitated and conveyed, and a supply conveyance path having a supply conveyance member for supplying the developer to the developer carrier, and the developer after completion of development from the developer carrier and collected. A recovery conveyance path having a recovery conveyance member that conveys the developer in the same direction as the supply conveyance member; and an agitation conveyance member that agitates and conveys the developer in a direction opposite to the supply conveyance member. Supplied to the body An agitating and conveying path that circulates and supplies the developer that has agitated the excess developer that has not been collected and the collected developer from the collecting and conveying path to the supply and conveying path. By using the one-way circulation system that collects all the developer at the collecting unit and does not return it to the supply unit, it is possible to always supply a developer having a constant toner concentration to the developing sleeve regardless of the output image. Further, it is possible to apply a uniform lubricant in the axial direction to an image carrier (for example, a photoreceptor).

  In the developing device of the third means of the present invention, in addition to the configuration of the first or second means, a toner storage portion containing at least unused toner, and a predetermined amount of toner in the toner storage portion are supplied to the developing device. Toner replenishing means for transferring to the main body, and the lubricant is mixed with unused toner in advance and stored in the toner storage unit, and is supplied to the developing device main body together with the toner by the toner replenishing means. There is no need to supply it separately, and it is easy to maintain.

  By the way, if there is a part where developer stress is applied to the developer in the developer circulation path of the developing device, the toner is fixed in the developing device or the toner is spent on the carrier, so that the life of the developer is remarkably shortened. There's a problem. Further, the developing ability is lowered due to the lubricant adhering to the carrier or the developing sleeve, and the lubricant cannot be supplied stably for a long time.

  Therefore, in the developing device of the fourth means of the present invention, in addition to the configuration of any one of the first to third means, the supply conveyance path and the stirring conveyance path are arranged substantially horizontally, and The collection conveyance path is arranged above the supply conveyance path and the agitation conveyance path, and the developer is lifted by the developing sleeve, and the portion where the developer is pushed up in the developer circulation section is eliminated. Thus, since no unnecessary stress is applied, the lubricant can be supplied stably in the long term. In addition, the apparatus can be made compact.

  In the developing device of the fifth means of the present invention, in addition to the configuration of any one of the first to third means, the recovery conveyance path, the supply conveyance path, and the stirring conveyance path are arranged substantially horizontally. By arranging the developer circulation part horizontally and eliminating the part that pushes up the developer in the developer circulation part, no unnecessary stress is applied, so the lubricant can be stably added over the long term. Supply can be made. Further, since the diameter of the stirring member can be easily increased, the developer circulation speed can be increased, and the lubricant can be stably supplied to the image carrier at a high linear velocity.

  In the present invention, the lubricant is uniformly mixed in the developer to prevent problems such as uneven application of the lubricant, toner scattering, and background contamination. In the developing device of the sixth means, the third to third In addition to the configuration of any one of the means 5, the lubricant is supplied to the developing device main body in the recovery transport path by the toner supply means, and the lubricant is supplied in the recovery transport path. Thus, the distance to which the replenished lubricant is conveyed can be increased, and the diffusibility is increased. Furthermore, the lubricant is surely dispersed in the developer by passing through the two delivery sections from the collection section to the stirring section and from the stirring section to the supply section. Accordingly, the concentration of the lubricant in the developing device can be kept constant, and a stable application of the lubricant to the image carrier can be performed. In addition, since the dispersibility of the replenishing toner is improved, it is possible to maintain image density stability.

In the developing device of the seventh means of the present invention, in addition to the constitution of any one of the first to sixth means, the fatty acid metal salt is excellent in lubricity by using a fatty acid metal salt as the lubricant, and Since it is easily transferred to the surface of the image carrier by an electric field, the lubricant can be stably applied to the image carrier.
In the developing device of the eighth means of the present invention, in addition to the constitution of any one of the first to sixth means, the fluorine-containing resin is excellent in lubricity by using a fluorine-containing resin as the lubricant. In addition, since it is easily transferred to the surface of the image carrier by an electric field, the lubricant can be stably applied to the image carrier.

In the developing device of the ninth means of the present invention, in addition to the constitution of the seventh means, the fatty acid metal salt is zinc stearate, so there are few side effects and excellent spreadability on the image carrier. ing.
In the developing device of the tenth means of the present invention, in addition to the constitution of the ninth means, the addition amount of the zinc stearate is 0.01 to 5% with respect to the toner weight. It is possible to stably supply zinc stearate from the developing device to the image carrier so as to keep the friction coefficient of the body low. If the addition amount is less than 0.01%, it is difficult to apply zinc stearate to the entire axial direction of the image carrier, resulting in uneven application. On the other hand, if the addition amount exceeds 5% and zinc stearate stays in the developing device, it is not preferable because it causes a decrease in the charge amount of the developer and development failure due to deterioration in fluidity.

In the developing device of the eleventh means of the present invention, in addition to the structure of the eighth means, the fluorine-containing resin is a polytetrafluoroethylene resin, so that there are few side effects and high lubricity can be obtained.
In the developing device of the twelfth means of the present invention, in addition to the structure of the eleventh means, the addition amount of the polytetrafluoroethylene resin is 0.01 to 5% with respect to the toner weight. The polytetrafluoroethylene (PTFE) resin can be stably supplied from the developing device to the image carrier so as to keep the coefficient of friction of the image carrier low. If the addition amount is less than 0.01%, it is difficult to apply the PTFE resin to the entire axial direction of the image carrier, resulting in uneven application. On the other hand, if the addition amount exceeds 5% and the PTFE resin stays in the developing device, it is not preferable because the charge amount of the developer is lowered and development failure is caused by the deterioration of fluidity.

  In the image forming apparatus of the thirteenth means of the present invention, an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer are housed to develop the electrostatic latent image. At least a developing device of any one of the first to twelfth means for visualizing the toner image and a transfer means for transferring the toner image on the image carrier to a recording material directly or via an intermediate transfer member Since the image is formed on the recording material, transferability is improved by forming an image using an image carrier to which a lubricant (fatty acid metal salt or fluorine-containing resin) is stably supplied. Thus, an image with excellent graininess can be obtained stably over a long period of time.

  In the image forming apparatus of the fourteenth means of the present invention, an image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer are housed to develop the electrostatic latent image. A plurality of image forming units each having at least a developing device of any one of the first to twelfth means that visualizes a toner image are provided for each color, and the toner image on the image carrier is directly applied to the recording material. Alternatively, the image forming apparatus includes at least transfer means for transferring via an intermediate transfer body, and forms toner images of each color on the image carrier of the plurality of image forming units, and then transfers the toner images to the recording material by the transfer means, and the recording Since a multicolor or color image is formed on the material, a color image is formed by using an image carrier to which a lubricant (fatty acid metal salt or fluorine-containing resin) is stably supplied in an image forming unit for each color. By transferring It can be improved and can be long-term stable good color image graininess and color reproducibility.

  In the image forming apparatus of the fifteenth means of the present invention, in addition to the configuration of the thirteenth or fourteenth means, a high-quality image can be obtained for a long time by using a charging roller to which an AC voltage is superimposed and applied to the charging device. Can be obtained stably. That is, in the image forming apparatus equipped with the developing device of the present invention, a lubricant (fatty acid metal salt or fluorine-containing resin) is effective as a protective film even in an AC charging system in which the surface of the image bearing member (photosensitive member) is heavily worn. Therefore, it contributes to extending the life of the image carrier (photosensitive member) and also obtains charging potential stability by AC charging, thereby improving the image quality.

  In the case of using the charging roller in contact with the image carrier with the above configuration, there is a problem that toner or lubricant adheres to the roller surface and soils the charging roller surface, causing charging failure. In the image forming apparatus of the sixteenth means, in addition to the structure of the fifteenth means, the charging roller is installed with a certain gap from the image carrier, so that the toner and lubricant on the roller surface Adhesion can be prevented and the life of the charging roller is extended. Therefore, an image having excellent graininess and color reproducibility can be obtained stably over a long period.

In the image forming apparatus of the seventeenth means of the present invention, in addition to the constitution of any one of the thirteenth to sixteenth means, the image carrier contains a filler in the surface layer, so that the image carrier Scraping can be prevented and the life of the image carrier is extended. Therefore, an image having excellent graininess and color reproducibility can be obtained stably over a long period.
In the image forming apparatus of the eighteenth means of the present invention, in addition to the structure of the seventeenth means, the mechanical strength of the surface of the image carrier is further improved by using at least one inorganic filler as the filler. And excellent wear resistance. Therefore, an image having excellent graininess and color reproducibility can be obtained stably over a long period.

Since the carrier of the nineteenth means of the present invention has a volume average particle diameter of 20 to 60 μm, the carrier having such a small particle diameter can be used as a developing device or a first one of the first to twelfth means. By using the image forming apparatus of any one of the thirteenth to eighteenth means, it is possible to improve the developing capability by densifying the magnetic brush, so that the pumping amount can be further reduced, and thereby the conveying member ( For example, the number of rotations of a screw or the like can be reduced, which contributes to reduction of stress due to developer circulation. Furthermore, since the magnetic brush in the development area becomes denser, high image quality and stable image quality are achieved.
When the volume average particle diameter of the carrier is larger than 60 μm, the developer overflows in the developer circulation portion, and stable developer circulation cannot be performed. Furthermore, since the magnetic brush becomes rough, satisfactory image quality cannot be obtained. On the other hand, if the volume average particle diameter of the carrier is less than 20 μm, there arises a problem that the carrier adheres to the image carrier or the carrier easily scatters from the developing device.

The toner of the twentieth means of the present invention has a volume average particle diameter (D4) of 3 to 8 μm, and the ratio (D4 / D1) of the volume average particle diameter (D4) to the number average particle diameter (D1) is , And a toner having a small particle size and a sharp particle size distribution, the developing device of any one of the first to twelfth means or the thirteenth to thirteenth means. By using it in the image forming apparatus of any one of the eighteenth means, the gap between the toner particles is reduced, so that the necessary amount of toner can be reduced without impairing the color reproducibility. Therefore, density fluctuation in development can be reduced. In addition, the stable reproducibility of a minute dot image is improved, and a stable and high-quality image can be obtained for a long time.
When the volume average particle diameter (D4) of the toner is less than 3 μm, problems such as a decrease in transfer efficiency and a decrease in blade cleaning properties are likely to occur. On the other hand, if the volume average particle diameter (D4) exceeds 8 μm, the fluidity of the developer deteriorates, and it is difficult to suppress scattering of characters and lines, and it is difficult to stably maintain image quality for a long period of time.

  The toner of the twenty-first means of the present invention has such a shape factor SF-1 in the range of 100 to 150, the shape factor SF-2 in the range of 100 to 150, and the toner is nearly spherical. By using nearly spherical toner in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means, the flowability of the developer is improved. Further, the stress in the developer circulation is further reduced, and the developer circulation and development can be performed stably over the long term, which can contribute to the stabilization of the image density.

The toner according to the twenty-second means of the present invention is such that such fine particles having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles. By using the toner in the developing device of any one of the first to twelfth means or the image forming apparatus of any one of the thirteenth to eighteenth means, there is less burying of the external additive in the toner, and over time. Since the change in developer fluidity and charging characteristics is small, it is possible to perform developer circulation and development more stably over the long term, which contributes to stabilization of image density.

  The developer of the twenty-third means of the present invention can achieve high image quality and stable image quality by using the carrier of the nineteenth means and the toner of any one of the twentieth to twenty-second means. In addition, density fluctuations during development can be reduced, stable reproducibility of minute dot images can be improved, and stable high-quality images can be obtained for a long period of time. Further, it becomes possible to perform developer circulation and development that are stable over a long period of time, which can contribute to stabilization of image density.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on the embodiments shown in the drawings.

<Explanation about development device>
The developing device according to the present invention will be described in detail based on the illustrated embodiment.
First, a configuration example of the developing device will be described with reference to FIG. FIG. 1 is a schematic cross-sectional configuration diagram showing one configuration example of the main body of the developing device 4. The main body of the developing device 4 is mainly composed of a developing roller 41 which is a developer carrying member and a recovery screw which is a recovery conveying member. The collection conveyance path 43a provided with 43b, the supply conveyance path 44a provided with the supply screw 44b as a supply conveyance member, the stirring conveyance path 45a provided with the stirring screw 45b as the stirring conveyance member, and the developer layer regulating member 42. And a recovery portion casing 46a, a recovery casing front end portion 46b, a toner concentration sensor 47, and the like. A developer composed of a toner and a carrier, to which a lubricant (for example, a fatty acid metal salt or a fluorine-containing resin) described later is added, is conveyed and circulated by a conveying member (screw) in each conveying path inside the developing device.

  The collection unit is disposed so that the axial center position of the recovery screw 43b is lower than the axial center position of the developing roller 41 and higher than the axial center positions of the supply screw 44b and the stirring screw 45b. The supply conveyance path 44a and the agitation conveyance path 45a communicate with each other at the end so that the developer circulates. In other portions, the developer is partitioned by the case, and the developer does not move between the supply conveyance path 44a and the agitation conveyance path 45a. In this embodiment, the developing roller 41 has an outer diameter of 18 mm, each screw has an outer diameter of 14 mm, and a shaft diameter of 5 mm. The screw pitch of each screw was 25 mm. Note that these values do not limit the configuration of the present invention, but are examples.

  As shown in FIG. 2, the developing roller 41 is mainly composed of a rotatable nonmagnetic developing sleeve 41a and a magnetic field generating means 41b fixed therein. As the magnetic field generating means 41b, a plurality of magnets (N1, S2, N2, N3, S1) fixedly arranged inside the developing sleeve 41a or a plurality of magnetic poles (N1, S2, N2, N3, S1) are magnetized. A magnetic field is generated around the developing sleeve 41a by these magnetic field generating means 41b. The normal component of the magnetic flux density on the sleeve surface is indicated by a broken line in the figure.

  The developer pumped up from the supply conveyance path 44a of the developing device 4 to the developing roller 41 by the magnetic pole N3 in the developing roller 41 is thinned by the developer layer regulating member 42 and is close to the photoreceptor 1 as an image carrier. Development is performed by being conveyed to the developing area (position of the developing magnetic pole N1). The collected developer that has passed through the developing region is separated from the developing roller 41 by the repulsive magnetic poles N2 and N3, and falls to the collecting and conveying unit 43a. Here, in FIG. 2, the value of the normal component of the magnetic flux density on the surface of the developing sleeve 41a at the position (dotted line portion) in the vicinity of the recovery casing tip 46b and the developing roller 41 needs to be 10 mT or less. If it exceeds 10 mT, the developer once separated from the developing roller 41 may adhere to the developing roller 41 again and enter the supply / conveyance unit.

  In addition, it is desirable that the recovery casing front end portion 46b and the developing roller 41 are installed in a predetermined gap without contacting each other. In this embodiment, a thin phosphor bronze plate is attached to the end of the recovery casing 46a at the recovery casing front end 46b, and the gap with the developing roller 41 is controlled to 1 mm. For example, when the member of the recovery casing tip 46b is installed in contact with the developing roller 41 using a member such as a mylar, the recovery agent return to the supply can be prevented initially, but the mylar and the developing roller during continuous operation. The toner enters and melts in the place where the friction is generated between them, and causes problems such as toner fixing to the developing sleeve 41a and aggregation of the developer.

Next, the flow of the developer will be described with reference to FIGS. FIG. 3 is a perspective view of the developing device 4, and FIG. 4 shows the flow of the developer (arrow) in FIG. 1 when the upper portion of the developing device is A and the lower portion is B.
The collected developer in the collection conveyance path 43a is conveyed by the collection screw 43b while increasing the amount downstream, and falls to the lower stirring conveyance path 45a from the opening 46c. The unused toner 5b is replenished by the toner replenishing means 5 on the collection conveyance path. In particular, when toner is replenished from above the opening 46c, the toner is replenished while being mixed when the recovery agent is dropped, so that the agitation is improved. In addition, since the toner replenishing means can be installed at the end of the collection unit, further downsizing can be achieved.

  As an example of the toner replenishing means 5, a uniaxial eccentric screw pump (common name: Mono pump) 50 as shown in FIG. 6A can be used. The toner storage container 52, which is a toner storage unit, stores unused toner to which a lubricant (for example, a fatty acid metal salt or a fluorine-containing resin) has been added in advance. Is sent to a uniaxial eccentric screw pump (Mono pump) 50. Alternatively, the toner may be temporarily stored in a toner bank or the like and then transported to the developing device 4. A cylindrical toner bottle or the like can be used as the toner storage container 52, and the toner is transported to the bottle opening by the rotation of the bottle by the spiral protrusion on the side surface of the bottle. The toner storage container 52 is not limited to a bottle shape, and may be a flexible shape.

  As shown in FIG. 6B, the structure of the MONO pump 50 includes a screw-shaped roller 50A that is eccentric using a rigid member such as metal or resin, and a stator that has a screw shape with two threads on the inside by a rubber material. 50B and a holder 50C containing both of these members, and one end of a toner replenishment conveyance path 51, which is a tube, is attached and connected to the toner storage container 52. When the roller 50A is rotated by the drive motor 50D, a suction pressure is generated in the pump, and the suction in the tube 51 is reduced. The toner in the storage container 52 is transferred by the suction force, and the developing device is supplied from the supply port 50F. It becomes possible to supply in. Further, the toner replenishment amount can be set finely by controlling the rotation operation (time) to the roller 50A by the replenishment clutch 50E connected to the drive motor 50D. The toner replenishing operation is performed mainly by calculating the necessary toner amount from the output value of the toner concentration sensor 47 so that the toner concentration of the developer in the developing device is fixed.

  The collected developer from the collection conveyance path 43a and the excess developer from the supply conveyance path 44a flow into the stirring conveyance path 45a. These developers are conveyed while being agitated to make the toner density uniform, and the developer is supplied upstream of the supply conveyance path 44a. The supply conveyance path 44a conveys the developer downstream while supplying the developer to the developing roller 41 while reducing the amount thereof. In this embodiment, the rotation speed of the developing sleeve 41a is 425 rpm, and the rotation speed of each screw is 480 rpm. This value is an example and is not limited.

  Further, as another form of the developing device 4, as shown in FIG. 5, it is possible to use one in which a collection conveyance path, a supply conveyance path, and a stirring conveyance path are arranged substantially horizontally. Also in this embodiment, since the stress during the developer conveyance is small, it is possible to perform a stable agent circulation over time. In addition, although the installation space is increased, increasing the size of the agitating member provides compatibility with high-speed image output. A detailed description of the developing device of FIG. 5 will be given below.

In FIG. 5, reference numeral 6 denotes a collection screw that is a collection conveyance member, 7 is a collection conveyance path, 8 is a supply screw that is a supply conveyance member, 9 is a supply conveyance path, 10 is an agitation conveyance path, and 11 is an agitation conveyance member. An agitating and conveying screw, 12 is a lower casing, 13 is an upper casing, 15 is a developing roller as a developer carrier, and 16 is a developer layer regulating member.
The screws 6, 8, 11 and the transport paths 7, 9, 10 are arranged in the lateral direction (substantially horizontal) below the developing roller 15. Each of the transport paths 7, 9, and 10 is formed by a partition plate that is held by an integrated lower casing 12 and upper casing 13. Here, the recovery transport path 7 and the supply transport path 9 are partitioned by a partition plate 134, and the supply transport path 9 and the stirring transport path 10 are partitioned by a partition plate 133. In the partition plate 134, the conveyance paths 7 and 9 are completely blocked in the image output area, that is, in the area where the developing roller 15 is located.

  The developing roller 15 is composed of a non-magnetic developing sleeve and magnetic field generating means fixedly disposed therein, like the developing roller of the developing device shown in FIGS. When the developer is supplied to the developing roller 15, it is desirable that the developer amount is larger than the developer amount regulated by the developer layer regulating member 16 even if an appropriate developer amount is fed. The surplus developer gradually increases on the upstream side 17 of the agent layer regulating member 16. A surplus developer collecting member 18 is installed to detour and return to the supply conveyance path 9 when the surplus developing developer stays and exceeds a certain amount so as not to cause circulation convection. . Further, the position of the excess developer collecting member 18 is set so that the reflux developer is not retained due to the magnetic force of the developing roller 15.

The developer layer regulating member 16 is tightly fixed to a heat radiating member 19 fixed to the upper casing 13. The developer layer regulating member 16 transmits heat from the developer to the heat radiating member 19, and fins 20 are formed inside the heat radiating member to dissipate heat by the air flow during operation, thereby reducing the temperature rise of the developer. I am trying. The heat radiating member 19 is provided with a guide portion 21 used as a guide guide when the developing device or the photosensitive unit (not shown) is attached to and detached from the machine main body (not shown). The lower casing 12 is provided with heat radiating fins 28 so that the temperature rise of the entire developing device can be reduced and cooled by cooling air sent from the front part of the machine to the rear part.
A developer catching roller 22 is installed on the downstream side of the developing roller 15 to catch the developer adhering to the photosensitive member 1 and the developer falling from the developing roller 15, and reversely rotate with the developing roller 15 to develop the developing roller 15. Or recovered by the scraper 23 to the recovery conveyance path 7.

Next, a configuration example of each conveyance path and each conveyance member constituted by the lower casing 12 will be described with reference to FIG. FIG. 9 is a perspective view of each conveyance path and each conveyance member formed by the lower casing as viewed from the photosensitive drum side.
In FIG. 9, the lower casing 12 is provided with a recovery screw 6, a supply screw 8, and a stirring and conveying screw 11 from the front of the figure, and each conveying path is formed in the lower casing 12 so as to surround each screw. Has been. However, the supply conveyance path 9 and the collection conveyance path 7 are held by an upper casing (not shown) and are separated by a partition plate 134 that engages with the lower casing 12. The partition plate 134 is installed sufficiently close to a developing roller (not shown) so that the developer does not enter the collecting section from the collecting section in the image forming area. The developer is conveyed in the directions of arrows 135 and 136 by the recovery screw 6 and the supply screw 8, and is conveyed in the direction of the arrow 137 in the reverse direction by the stirring and conveying screw 11.

The configuration of each screw will be described using the stirring and conveying screw 11 as an example. The agitating and conveying screw 11 is fed with a conveying screw 138 for agitating and conveying the developer in the developer conveying direction, a transfer paddle 139 for transferring the developer to the adjacent supply screw 8 side, and the developer into the bearing portion. A reversing screw 140 having a winding direction opposite to that of the conveying screw 138 is provided. Further, the recovery screw 6 and the supply screw 8 have the same configuration.
The shape of the screw in this example is
Stirring screw: outer diameter φ30mm, pitch 36mm (twice)
Supply screw: outer diameter φ27mm, pitch 36mm (2 items)
Recovery screw: Outer diameter φ25mm, Pitch 34mm (2 items)
It is said. However, this value is an example and is not limited.

  On the downstream side of the developer conveyance direction, each conveyance path is connected, and the developer from the agitation conveyance path is transferred to the supply screw 8 side by the transfer paddle 139 of the agitation conveyance screw 11 and is supplied to a developing roller (not shown). Supplied. Further, the collected developer from the collection conveyance path is transferred to the supply screw 8 side by the transfer paddle 131 of the collection screw 6 and further supplied together with the developer in the supply conveyance path that has not been sent to the developing roller (not shown). The screw 8 is transferred to the stirring and conveying screw 11 side by the transfer paddle 132.

Next, the characteristics of the developer used in the present invention will be described.
The carrier preferably has a volume average particle size of 20 to 60 μm. By using a carrier having a small particle size with a volume average particle size of 60 μm or less, the pumping amount can be reduced without lowering the developing ability, and the amount of developer circulating in the developing device can be reduced. . In particular, the amount of developer passing through the stressed developer layer regulating member is reduced, which contributes to a longer life. Furthermore, since the magnetic brush in the development area becomes denser, further image quality improvement and image quality stability are achieved. When the volume average particle diameter of the carrier is larger than 60 μm, overflow tends to occur in the developer circulation portion, and stable agent circulation cannot be performed. On the other hand, when the volume average particle size is smaller than 20 μm, there is a problem that the carrier adheres to the photosensitive member or the carrier easily scatters from the developing device.
The average particle size of the carrier can be measured using a SRA type of a Microtrac particle size analyzer (Nikkiso Co., Ltd.) with a range setting of 0.7 [μm] or more and 125 [μm] or less.

Next, the characteristics of the toner will be described.
As for the particle diameter of the toner, the volume average particle diameter (D4) of the toner is preferably 3 to 8 μm. By using a toner having a small particle size and a sharp particle size distribution, the gap between the toner particles is reduced, so that the necessary amount of toner can be reduced without impairing the color reproducibility. Therefore, density fluctuation in development can be reduced. Further, the stable reproducibility of a minute dot image of 600 dpi or more is improved, and a stable high image quality can be obtained for a long time. On the other hand, when the volume average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties tend to occur. When the volume average particle diameter (D4) exceeds 8 μm, the pile height of the image becomes large and it is difficult to suppress scattering of characters and lines.

At the same time, the ratio (D4 / D1) of the volume average particle diameter (D4) to the number average particle diameter (D1) is preferably in the range of 1.00 to 1.40.
The closer the ratio (D4 / D1) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

Next, a method for measuring the particle size distribution of toner particles will be described.
Examples of the measuring device for the particle size distribution of toner particles by the Coulter counter method include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.

  First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the measurement device is used to measure the volume and number of toner particles or toner using a 100 μm aperture as an aperture. Volume distribution and number distribution are calculated. From the obtained distribution, the volume average particle diameter (D4) and the number average particle diameter (D1) of the toner can be obtained.

  As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.

The shape factor SF-1 of the toner is preferably in the range of 100 to 150, and the shape factor SF-2 is preferably in the range of 100 to 150. 7 and 8 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape, and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting toner onto a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes irregular as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). This is a value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner onto the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) ² / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, unevenness does not exist on the toner surface, and as the SF-2 value increases, the unevenness of the toner surface becomes more prominent.

Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.) and introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) for analysis. And calculated.
When the shape of the toner is close to a sphere, the contact state between the toners becomes a point contact, so that the attractive force between the toners is weakened and the fluidity is increased. Therefore, since the developer circulation is improved, the stress is reduced, and stable one-way circulation can be performed in the long term. In addition, since the contact state between the toner and the photoconductor is a point contact, the attractive force between the toner and the photoconductor is weakened, and the transfer rate is increased, which contributes to high image quality. On the other hand, if any of the shape factors SF-1 and SF-2 exceeds 150, the fluidity is deteriorated and the developer circulation is poor, which is not preferable. Also, the transfer rate is lowered, which is not preferable.

The toner of the present invention is obtained by attaching fine particles (hereinafter simply referred to as fine particles) having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 mg / cm ³ or more to the toner particle surface. In addition, although silica etc. are often used for a normal fluid improvement agent, for example, the average primary particle diameter of this silica is 10-30 nm normally, and a bulk density is 0.1-0.2 mg / cm < ³ >.

  In the present invention, since fine particles having appropriate characteristics are present on the surface of the toner, an appropriate gap is formed between the toner particles and the object. Further, the fine particles have a very small contact area with the toner particles, the photoconductor, and the charge imparting member and are evenly contacted with each other. Further, since the fluidity of the developer is increased, there is an effect of reducing stress, which contributes to a longer life. Furthermore, since it plays the role of a roller, it is difficult to be buried in toner particles even during cleaning under high stress (high load, high speed, etc.) between the cleaning blade and the photoconductor without wearing or damaging the photoconductor. Or, even if it is buried a little, it can be detached and returned, so that stable characteristics can be obtained over a long period of time. Further, the toner is moderately detached from the surface of the toner and accumulated at the tip of the cleaning blade, and the so-called dam effect has an effect of preventing a phenomenon that the toner passes from the blade. Since these characteristics have an effect of reducing the share received by the toner particles, the filming effect of the toner itself due to the low rheological component contained in the toner is exhibited for high-speed fixing (low energy fixing). In addition, when fine particles having an average primary particle size in the range of 50 to 500 μm are used, the excellent cleaning performance can be fully utilized, and since the particle size is extremely small, the powder fluidity of the toner is improved. There is no reduction. Further, although the details are not clear, even if the surface-treated fine particles are externally added to the toner or the carrier is contaminated, the degree of developer deterioration is small. Accordingly, since the change in toner fluidity and chargeability with time is small, the developer can be circulated stably over a long period of time. Also, the stability of image quality is increased.

  The average primary particle size (hereinafter referred to as the average particle size) of the fine particles is 50 to 500 nm, and preferably 100 to 400 nm. If the thickness is less than 50 nm, the fine particles may be buried in the concave and convex portions on the toner surface to lower the role of the rollers. On the other hand, when the particle size is larger than 500 μm, when the fine particles are located between the blade and the surface of the photosensitive member, the toner particles have an order of the same level as the contact area of the toner itself, and the toner particles to be cleaned pass through. That is, it becomes easy to generate a cleaning defect.

In addition, if the bulk density is less than 0.3 mg / cm ³ , although there is a contribution to improving fluidity, the scattering property and adhesion of the toner and fine particles become high. Accumulation reduces the work of the so-called dam effect that prevents toner cleaning failure.

In the fine particles added to the toner of the present invention, the inorganic compounds include SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , BaO, CaO, K ₂ O. , Na ₂ O, ZrO ₂ , CaO.SiO ₂ , K ₂ O (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO _3, etc. can preferably _{include SiO 2, TiO 2, Al 2} O 3. In particular, these inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like.

  The organic compound fine particles may be thermoplastic resins or thermosetting resins, such as vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenol resins, melamine resins, Examples include urea resins, aniline resins, ionomer resins, and polycarbonate resins. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained.

  Specific examples of vinyl resins include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid. -Acrylic ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, and the like.

The bulk density of the fine particles was measured by the following method. Using a 100 ml graduated cylinder, fine particles were gradually added to make 100 ml. At that time, no vibration was applied.
The bulk density was measured by the difference in weight before and after placing the fine particles of the graduated cylinder.
Bulk density (g / cm ³ ) = fine particle amount (g / 100 ml) ÷ 100

  The fine particles of the present invention can be externally added and adhered to the toner surface by mechanically mixing and adhering the toner base particles and fine particles using various known mixing devices, or in the liquid phase. There is a method in which the base particles and the fine particles are uniformly dispersed with a surfactant or the like, and are dried after the adhesion treatment.

Further, in the present invention, a lubricant is contained in the developer for the purpose of imparting lubricity to the surface of the photoreceptor and protecting the photoreceptor surface from the charging process. Here, examples of the lubricant used in the present invention include fatty acid metal salts and fluorine-containing resins.
As the form, a fatty acid metal salt or a finely divided fluorine-containing resin is preferably used. Fine particles of these fatty acid metal salts or fluorine-containing resins are supplied to the photosensitive member together with the toner mainly by a developing electric field, and then are rubbed with a cleaning member to form a thin film on the photosensitive member. In addition, the photosensitive member surface protecting function is exhibited.

Fatty acid metal salts used as lubricants in the present invention include barium stearate, calcium stearate, zinc stearate, aluminum stearate, magnesium stearate, lithium stearate, lead stearate, barium laurate, calcium laurate, zinc laurate , Magnesium laurate, lithium laurate, lead laurate, calcium palmitate, magnesium palmitate, zinc palmitate, dibasic lead stearate, etc. Among them, zinc stearate has the least side effect and is a photoreceptor. It can be suitably used because of its excellent upward spreadability. The addition amount is preferably in the range of 0.01 to 5% with respect to the toner weight. When the content is 0.01% or less, lubricity is not sufficiently imparted to the surface of the photoreceptor. On the other hand, if it exceeds 5%, the influence on the developer characteristics becomes large, the charge amount decreases and causes toner scattering, or the fluidity deteriorates and the developer cannot be sufficiently pumped up on the developing roller, etc. This is not preferable because of the above problems.
In the present invention, only one kind of these fatty acid metal salts may be used, or two or more kinds may be mixed and used.

In addition, as the fluorine-containing resin used as a lubricant in the present invention, polytetrafluoroethylene resin (PTFE), perfluoroalkoxy / fluorine resin (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP) , Ethylene / tetrafluoroethylene copolymer (ETFE), polychlorotrifluoride ethylene (PCTFE), vinylidene fluoride (PVDF), vinyl fluoride (PVF), etc., among which polytetrafluoroethylene Resin (PTFE) can be suitably used because it has the fewest side effects and provides excellent lubricity. The addition amount is preferably in the range of 0.01 to 5% with respect to the toner weight. When the content is 0.01% or less, lubricity is not sufficiently imparted to the surface of the photoreceptor. On the other hand, if it exceeds 5%, the influence on the developer characteristics becomes large, the charge amount decreases and causes toner scattering, or the fluidity deteriorates and the developer cannot be sufficiently pumped up on the developing roller, etc. This is not preferable because of the above problems.
In the present invention, only one kind of these fluorine-containing resins may be used, or two or more kinds may be mixed and used. In this example, when a fluorine-containing resin was used as a lubricant, 0.5% of PTFE fine particles were added as a fluorine-containing resin with respect to the toner weight.

<Detailed description of the entire image forming apparatus>
An embodiment of the image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 10 is a schematic central sectional view showing the internal configuration of the image forming apparatus 100. The image forming apparatus 100 superimposes four color image forming units 90y, 90m, 90c, and 90k that form toner images of each color (y: yellow, m: magenta, c: cyan, k: black), and toner images of the respective colors. The intermediate transfer belt 60A that is transported together, and the intermediate transfer section 60 that includes a plurality of rollers 63 to 66 and the primary transfer roller 61 on which the intermediate transfer belt 60A is stretched, and recording materials (for example, sheets) P1 and P2 of different sizes. On the intermediate transfer belt 60A of the intermediate transfer unit 60, a paper storage unit 71 for feeding the recording material, a paper feed unit 73 for feeding the recording material (paper), a paper transport unit P for transporting the recording material (paper). The toner image is transferred to a recording material, a secondary transfer portion (for example, a secondary transfer roller) 62, and an unfixed toner image on the recording material is stretched between rollers 82 and 83 provided with heating means. A fixing unit (fixing device) 80 that fixes the toner 81 and the pressure roller 84, a discharge roller 74 that discharges the recording material after fixing, and each color (y: yellow, m: magenta, c: cyan, k: It is mainly composed of toner storage containers 52y, 52m, 52c, and 52k that store unused toner (black) and an image processing unit (not shown).

Since the four image forming units 90y, 90m, 90c, and 90k have the same configuration, only one image forming unit 90 (y to k) will be described here with reference to FIG. FIG. 11 is a schematic cross-sectional view showing a configuration example of one image forming unit.
The image forming unit 90 includes a photosensitive member 1 as an image carrier, a charging device 2 using a charging roller, and the developing device 4 according to the present invention described above (for example, the developing device having the configuration shown in FIGS. 1 and 2). And a cleaning device 70 using a cleaning blade for removing transfer residual toner after transfer from the photoreceptor 1.

Next, operations of the image forming unit 90 and the image forming apparatus 100 will be described.
When an image output command is sent to the image forming apparatus 100 from an input device such as a personal computer (PC) or a scanner (not shown), the image signal is subjected to image processing by an image processing unit (not shown) and each color (y: yellow, m: magenta, c: cyan, k: black) and then sent to the exposure apparatus 30. As the exposure apparatus 30, for example, a laser scanning type exposure apparatus using a laser light source, an optical deflector (polygon mirror, etc.), a scanning imaging optical system, or the like is used. In the image forming units 90 (y to k) of the respective colors, the photoconductor 1 is driven, and the photoconductor 1 is uniformly charged by the charging device 2. Thereafter, exposure 3 according to the image signal is performed by the exposure device 30, and an electrostatic latent image is formed on the photoreceptor 1. The electrostatic latent image is developed with the developer toner carried on the sleeve 41 a of the developing roller 41 in the developing unit of the developing device 4 to be visualized as a toner image. The toner image on the photoreceptor 1 is transferred to the intermediate transfer belt 60 </ b> A by applying a bias to the primary transfer roller 61. The transfer residual toner remaining on the photoreceptor 1 after the transfer is removed by a cleaning blade or the like of the cleaning device 70 to clean the surface of the photoreceptor, and then the operation is performed in a cycle in which charging for the next image formation is performed. The The toner consumed in the development is supplied from the toner storage container 52 to each developing device 4 using the toner supply means 50 as shown in FIG.

  On the other hand, the transfer of the toner image to the intermediate transfer belt 60A is sequentially performed from the image forming units 90y, 90m, 90c, and 90k of the respective colors, and the toner images of the respective colors are superimposed on the intermediate transfer belt 60A. The recording material P <b> 1 (or P <b> 2) is fed by the paper feed roller 73 from the paper storage unit 71 (or 72), passes through the paper transport unit P, and the toner image is transferred at the secondary transfer unit 62. The recording material on which the unfixed toner image is placed enters the fixing unit (fixing device) 80, whereby the toner is fused and fixed to the recording material by heat and pressure. Then, the recording material on which the toner image is fixed is output to the outside of the image forming apparatus by the paper discharge roller 74, and the image formation is completed.

In the above embodiment, an example of the configuration and operation of a tandem color image forming apparatus including four image forming units has been described. However, an image forming unit 90 as shown in FIG. 11 may be used alone. It can be used in an image forming unit such as a printer, a copying machine, or a facsimile machine that forms a monochrome image.
In the image forming unit shown in FIG. 11, the photosensitive member 1, the charging device 2, and the cleaning device 7 are integrated to form a process cartridge, which improves maintenance such as assembly, adjustment, and replacement. Further, by assembling the developing device 4 integrally with the process cartridge, the assembly or replacement of the image forming unit 90 is further facilitated.

<Description of charging device>
Next, the charging device 2 used in the image forming apparatus of the present invention will be described. The charging device 2 charges the photoreceptor 1 using proximity discharge. As a method of charging the photosensitive member 1 using proximity discharge, a contact charging method in which a rotatable roller-shaped charging member (hereinafter referred to as a charging roller) is disposed in contact with the photosensitive member 1, and a charging roller is photosensitive. There is a non-contact charging method in which the body 1 is arranged in a non-contact manner. In this embodiment, a non-contact charging method is used.

  The present invention can also be applied to a contact charging method. However, in the contact charging method, it is preferable to use an elastic member that improves the contact property with the surface of the photoreceptor and does not apply mechanical stress to the photoreceptor. However, when an elastic member is used, the charging nip width is widened, which may cause toner and lubricant (fatty acid metal salt or fluorine-containing resin) to easily adhere to the charging roller side. Therefore, it is more advantageous to adopt a non-contact charging method for high durability. In this embodiment, as shown in FIG. 12, a non-contact charging method in which a charging roller 121 is disposed so as to face at least an image forming area on the surface of the photoreceptor with a predetermined charging gap 114 is employed.

Here, FIG. 12 is an explanatory diagram of the non-contact charging type charging device 2 used in the image forming apparatus of the present invention.
The charging roller 121 includes a shaft portion 121a and a roller portion 121b. The roller part 121b can be rotated by the rotation of the shaft part 121a, and the part of the surface of the photosensitive member 1 facing the image forming area 111 where an image is formed is not in contact with the photosensitive member 1. The charging roller 121 is set to have a length in the longitudinal direction (axial direction) slightly longer than the image forming area, and spacers 122 are provided at both ends in the longitudinal direction. These two spacers are brought into contact with the non-image forming regions 112 at both ends of the surface of the photoconductor to form a minute gap 114 between the photoconductor 1 and the charging roller 121. The minute gap 114 is configured such that the distance at the closest portion between the charging roller 121 and the photosensitive member 1 can be maintained at 5 to 100 [μm]. A more preferable range of the gap 114 is 30 to 65 [μm], and is set to 50 μm in the apparatus of the present invention. Further, the shaft portion 121a is pressed against the photosensitive member side by a pressing spring 115 made of a spring. Thereby, the minute gap 114 can be accurately maintained. Further, the charging roller 121 rotates along with the surface of the photoreceptor via the spacer 122.

  A charging power source 116 is connected to the charging roller 121. As a result, the surface of the photoconductor is uniformly charged by proximity discharge in a minute gap between the surface of the photoconductor and the surface of the charging roller. In the present invention, an alternating voltage obtained by superimposing an AC voltage that is an AC component on a DC voltage that is a DC component is used as the applied voltage. When an alternating voltage obtained by superimposing an AC voltage on a DC voltage is applied as an applied voltage to the charging roller 121, influences such as variations in charging potential due to minute gap fluctuations are suppressed, and uniform charging becomes possible.

  The charging roller 121 includes a cored bar as a conductive support having a cylindrical shape, and a resistance adjusting layer formed on the outer peripheral surface of the cored bar. The surface of the charging roller 121 is desirably hard. A rubber member can also be used as the roller member. However, if the member is easily deformed, such as a rubber member, it is difficult to maintain the minute gap 114 between the photosensitive member 1 and the central portion of the charging roller 121 depending on image forming conditions. Only can suddenly contact the photoreceptor surface. Since it is difficult to cope with the disturbance of toner and lubricant (fatty acid metal salt or fluorine-containing resin) caused by charging roller 121 locally or suddenly contacting the surface of the photoreceptor, a non-contact charging method is used. In this case, a hard member with less bending is desirable.

  Specific examples of the charging roller 121 having a hard surface include, for example, a thermoplastic resin composition (polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and a copolymer thereof, etc.) in which a polymer ion conductive agent is dispersed in a resistance adjustment layer. ), And the surface of the resistance adjustment layer is cured with a curing agent. The cured film treatment is performed, for example, by immersing the resistance adjustment layer in a treatment solution containing an isocyanate-containing compound, but may be performed by forming a cured treatment film layer on the surface of the resistance adjustment layer. . In this embodiment, the charging roller 121 is formed with a diameter of 10 mm.

<Description of photoconductor>
Next, the photoreceptor 1 used as an image carrier in the image forming apparatus of the present invention will be described in detail.
The photosensitive member 1 in this embodiment is a negatively charged organic electrophotographic photosensitive member (OPC) having a photosensitive layer provided on a drum-shaped conductive support (or conductive substrate) having a diameter of 30 mm. As the photoreceptor used in the present invention, those generally known as an organic electrophotographic photoreceptor in which an organic photosensitive layer is provided on a conductive support can be used. Among them, as shown in FIG. A function-separated type photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated is most preferably used from the viewpoint of performance. Here, (a) in the figure is a conductive support (substrate), (a) is a charge generation layer, and (c) is a charge transport layer.

Examples of the drum-like or belt-like conductive support (a) that can be used in the present invention include metals or alloys such as Al, Ni, Fe, Cu, and Au; plastics such as polyester, polycarbonate, and polyimide; Examples thereof include a metal film such as Al, Ag, Au, or a metal oxide film such as In ₂ O ₃ or SnO ₂ provided on an insulating substrate.
The function-separated type photoreceptor is formed by laminating a charge generation layer (A) and a charge transport layer (C) on these conductive supports (A).

  The charge generation layer (a) may be formed from only the charge generation material or may be formed by uniformly dispersing the charge generation material in the binder. The charge generation layer (A) is formed by dispersing these components in a suitable solvent, and applying and drying this on the conductive support (A).

  Examples of the charge generation material include CIP Pigment Blue 25 (Color Index (CI21180), CIG Pigment Red 52 (CI45100), CII Basic Red 3 (CI45210), etc.), a phthalocyanine pigment having a porphyrin skeleton, and a carbazole skeleton. An azo pigment (see Patent Document 5), an azo pigment having a stilbene skeleton (see Patent Document 6), an azo pigment having a distyrylbenzene skeleton (see Patent Document 7), an azo pigment having a triphenylamine skeleton (see Patent Document 8) ), An azo pigment having a dibenzothiophene skeleton (see Patent Document 9), an azo pigment having an oxadiazole skeleton (see Patent Document 10), an azo pigment having a fluorenone skeleton (see Patent Document 11), an azo having a bisstilbene skeleton Pigment (see Patent Document 12), Distil An azo pigment having an oxadiazole skeleton (see Patent Document 13), an azo pigment having a distyrylcarbazole skeleton (see Patent Document 14), a trisazo pigment having a carbazole skeleton (see Patent Document 15 and Patent Document 16), and the like, Furthermore, phthalocyanine pigments such as C.I. Pigment Blue 16 (CI74100), indigo pigments such as C.I.But Brown 5 (CI173410), perylenes such as Argo Scar Red B (manufactured by Violet), Indence Scarlet R (manufactured by Bayer) Organic pigments such as pigments and squaric pigments can be used.

As the binder resin, polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like are used.
The amount of the binder resin is 5 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the charge generating material.
Solvents used here are single solvents or mixed solvents such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, cyclohexane, methyl ethyl ketone, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, dichloromethane, and ethyl cellosolve. Is preferred.
The average film thickness of the charge generation layer is 0.01 to 2 μm, preferably 0.1 to 1 μm.

The charge transport layer (c) is formed by dissolving a charge transport material, a binder resin and, if necessary, a plasticizer and a leveling agent in a suitable solvent, coating the charge transport layer on the charge generation layer, and drying.
Examples of charge transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, imidazole derivatives, Electron donating properties such as triphenylamine derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-stilbene derivatives Substances.
Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinyl chloride, polyvinylidene chloride, polyacrylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine resin And thermoplastic or thermosetting resins such as urethane resin, phenol resin, and alkyd resin.

Solvents for forming the charge transport layer include tetrahydrofuran, dioxane, toluene, monochlorobenzene, 1,2-dichloroethane, cyclohexanone, dichloromethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane and These mixed solvents are desirable.
The film thickness of the charge transport layer is 10 to 100 μm, preferably 20 to 40 μm.

  In the present invention, an undercoat layer may be provided between the conductive support (A) and the charge generation layer (A) as necessary in order to improve adhesion and charge blocking properties. Furthermore, a protective layer may be provided on the outermost surface in order to improve wear resistance.

  In the present invention, as shown in FIG. 14, a filler may be contained in the surface layer of the photoreceptor in order to improve the wear resistance and to improve the coating property of the lubricant (fatty acid metal salt or fluorine-containing resin). preferable. Here, (D) in the figure is the photoreceptor surface layer, and (E) is the filler. In the present invention, the surface layer is a layer provided on the outermost surface of the photoreceptor, and is generally a charge transport layer or a protective layer.

As the filler (e) contained in the surface layer (d), either an organic filler or an inorganic filler may be used, but an inorganic filler is particularly preferably used from the viewpoint of improving mechanical strength.
Examples of the organic filler material include fluororesin powder such as polytetrafluoroethylene, silicone resin powder, and a-carbon powder. Inorganic filler materials include silica, tin oxide, zinc oxide, titanium oxide, alumina, and oxide. Metal oxides such as zirconium, indium oxide, antimony oxide, bismuth oxide, calcium oxide, tin oxide doped with antimony, tin-doped indium oxide, metal fluorides such as tin fluoride, calcium fluoride, aluminum fluoride, Examples thereof include potassium titanate and boron nitride. These fillers may be used alone or in combination of two or more. In order to improve dispersibility, these fillers may be surface treated with a surface treatment agent.

These fillers can be used by dispersing in the surface layer coating solution by a known means such as a ball mill or a sand mill. As content of a filler, 5 to 40 weight% is preferable with respect to the total solid, More preferably, it is 10 to 30%. Further, the volume average particle diameter of the filler is preferably 0.05 to 1.0 μm as described above.

  In the experiments of the present inventors, the photoreceptor containing the filler in the surface layer as described above has a wear amount of 3 to 3 times during repeated use in the copying process as compared with the conventional photoreceptor containing no filler. It is about 10 times less and has a configuration that can greatly improve the wear resistance. Furthermore, it has been confirmed that the change in surface roughness due to the inclusion of the filler is also advantageous for the coating property of the lubricant (fatty acid metal salt or fluorine-containing resin), and prevents the photoreceptor surface deterioration. There is also a merit that the amount of lubricant (fatty acid metal salt or fluorine-containing resin) required for the treatment is small compared with the case where no filler is contained.

  10 and 11, the unidirectional circulation type developing device 4 of the present invention shown in FIGS. 1 and 5 and the conventional biaxial conveying type as shown in FIG. A durability test was performed using a developing device. Here, a random pattern is generated using the output image as an error factor. As a result, in the conventional biaxial conveying type developing device, an abnormality such as a black streak occurs in an image with about 20,000 sheets, whereas the one-way circulation system of the present invention shown in FIGS. In this developing device, it was found that durability of 50,000 sheets or more was obtained, and it was confirmed that the lubricant (fatty acid metal salt or fluorine-containing resin) was stably applied to the photoreceptor 1 over time. It was.

It is a figure which shows one Example of this invention, Comprising: It is a general | schematic cross-section block diagram which shows one structural example of a developing device (developing device main body). FIG. 2 is an explanatory diagram of a developing sleeve and a magnetic field generating unit constituting a developing roller of the developing device shown in FIG. 1 and a magnetic field generated by the magnetic field generating unit. FIG. 2 is a perspective view showing a state in which an upper case of the individual developing device shown in FIG. 1 is removed. FIG. 2 is a diagram showing a flow (arrow) of developer in each case where A is the upper part of the developing device and B is the lower part in FIG. 1. It is a figure which shows another Example of this invention, Comprising: It is a general | schematic cross-section block diagram which shows one structural example of the developing device by which the collection conveyance path, the supply conveyance path, and the stirring conveyance path are arrange | positioned substantially horizontally. FIG. 4 is a diagram illustrating a configuration example of a toner supply unit. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2. FIG. 6 is a perspective view of each conveyance path and each conveyance member configured by the lower casing of the developing device illustrated in FIG. 5 as viewed from the photosensitive drum side. 1 is a schematic central cross-sectional view illustrating an internal configuration of an image forming apparatus according to an exemplary embodiment of the present invention. It is a schematic sectional drawing which shows the structural example of the image forming unit used for the image forming apparatus shown in FIG. It is an explanatory view of a non-contact charging type charging device used in the image forming apparatus of the present invention. It is a schematic principal part sectional drawing which shows an example of the layer structure of an organic electrophotographic photoreceptor. FIG. 3 is a schematic cross-sectional view of an essential part showing an example in which a filler is contained in a surface layer of a photoreceptor. It is a schematic sectional drawing which shows the structural example of the conventional biaxial conveyance type developing apparatus.

Explanation of symbols

1: Photoconductor (image carrier)
2: Charging device 3: Exposure 4: Developing device (developing device body)
5: Toner replenishing means 6: Recovery screw (recovery conveying member)
7: Recovery conveyance path 8: Supply screw (supply conveyance member)
9: Supply conveyance path 10: Stirring conveyance path 11: Stirring conveyance screw (stirring conveyance member)
15: Developing roller (developer carrier)
16: Developer layer regulating member 41: Developing roller (developer carrier)
41a: developing sleeve 41b: magnetic field generating means 42: developer layer regulating member 43a: recovery conveyance path 43b: recovery screw (recovery conveyance member)
44a: supply conveyance path 44b: supply screw (supply conveyance member)
45a: Stirring conveyance path 45b: Stirring screw (stirring conveyance member)
46a: Collection unit casing 46b: Collection casing tip 47: Toner concentration sensor 50: Uniaxial eccentric screw pump (toner supply means)
51: Toner supply transport tube 52: Toner storage container (toner storage unit)
60: Intermediate transfer portion 60A: Intermediate transfer belt (intermediate transfer member)
61: Primary transfer roller 62: Secondary transfer portion (secondary transfer roller)
70: Cleaning device 71, 72: Paper storage unit 80: Fixing device 90: Image forming unit 97: Cleaning device 121: Charging roller P1, P2: Recording material (paper)

Claims (23)

A developing device main body internally provided with a developer composed of toner and carrier to which at least a lubricant is added;
A developer carrying body provided in the developing device main body and carrying and carrying the developer as a magnetic brush;
A supply conveyance path having a supply conveyance member for agitating and conveying the developer along the axial direction of the developer carrying body and supplying the developer to the developer carrying body;
A recovery transport path having a recovery transport member for recovering the developer after completion of development from the developer carrier and transporting the recovered developer in the same direction as the supply transport member;
An agitating and conveying member that agitates and conveys in a direction opposite to the supply and conveying member, and agitates the surplus developer that has not been supplied from the supply and conveying path to the developer carrier and the collected developer from the collecting and conveying path; An agitating and conveying path that circulates and supplies the developer to the supply and conveying path
A developing device comprising: The developing device according to claim 1,
The developer carrying member comprises a non-magnetic developing sleeve and a magnetic field generating means fixedly disposed in the sleeve. The developing device according to claim 1 or 2,
A toner storage unit containing at least unused toner, and a toner replenishing means for transferring a predetermined amount of toner in the toner storage unit to the developing device body,
The developing device, wherein the lubricant is mixed with unused toner in advance and stored in the toner storage unit, and is supplied to the developing device main body together with the toner by the toner replenishing means. The developing device according to any one of claims 1 to 3,
The supply conveyance path and the stirring conveyance path are arranged substantially horizontally,
The developing conveyance path is disposed above the supply conveyance path and the agitation conveyance path. The developing device according to any one of claims 1 to 3,
The developing device, wherein the recovery conveyance path, the supply conveyance path, and the agitation conveyance path are arranged substantially horizontally. The developing device according to any one of claims 3 to 5,
The developing device according to claim 1, wherein the lubricant is replenished to the developing device main body in the collecting and conveying path by the toner replenishing means. The developing device according to any one of claims 1 to 6,
The developing device, wherein the lubricant is a fatty acid metal salt. The developing device according to any one of claims 1 to 6,
The developing device, wherein the lubricant is a fluorine-containing resin. The developing device according to claim 7.
The developing apparatus, wherein the fatty acid metal salt is zinc stearate. The developing device according to claim 9, wherein
The developing device according to claim 1, wherein the amount of zinc stearate added is 0.01 to 5% based on the toner weight. The developing device according to claim 8, wherein
The developing device, wherein the fluorine-containing resin is a polytetrafluoroethylene resin. The developing device according to claim 11, wherein
The developing device according to claim 1, wherein the polytetrafluoroethylene resin is added in an amount of 0.01 to 5% based on the toner weight.   13. An image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer that contains the developer and develops the electrostatic latent image into a toner image. At least a developing device according to claim 1 and a transfer unit that transfers the toner image on the image carrier directly to the recording material or via an intermediate transfer body, and forms an image on the recording material. An image forming apparatus.   13. An image carrier that carries an electrostatic latent image, a charging device that charges the image carrier, and a developer that contains the developer and develops the electrostatic latent image into a toner image. A transfer unit that includes a plurality of image forming units each including at least the developing device according to any one for each color, and that transfers a toner image on the image carrier to a recording material directly or via an intermediate transfer member. At least, forming a toner image of each color on the image carrier of the plurality of image forming units, and then transferring the toner image to the recording material by the transfer unit to form a multicolor or color image on the recording material. An image forming apparatus. The image forming apparatus according to claim 13 or 14,
An image forming apparatus, wherein a charging roller to which an AC voltage is applied is used as the charging device. The image forming apparatus according to claim 15.
The image forming apparatus, wherein the charging roller is installed with a certain gap from the image carrier. The image forming apparatus according to any one of claims 13 to 16,
The image forming apparatus, wherein the image bearing member contains a filler in a surface layer. The image forming apparatus according to claim 17.
An image forming apparatus using at least one inorganic filler as the filler. A developer carrier for use in the developing device according to any one of claims 1 to 12 or the image forming apparatus according to any one of claims 13 to 18.
A carrier having a volume average particle diameter of 20 to 60 μm. A developer toner for use in the developing device according to any one of claims 1 to 12 or the image forming apparatus according to any one of claims 13 to 18,
The volume average particle diameter (D4) is 3 to 8 μm, and the ratio (D4 / D1) of the volume average particle diameter (D4) to the number average particle diameter (D1) is in the range of 1.00 to 1.40. A toner characterized by being. A developer toner for use in the developing device according to any one of claims 1 to 12 or the image forming apparatus according to any one of claims 13 to 18,
A toner having a shape factor SF-1 in the range of 100 to 150 and a shape factor SF-2 in the range of 100 to 150. A developer toner for use in the developing device according to any one of claims 1 to 12 or the image forming apparatus according to any one of claims 13 to 18,
A toner characterized in that fine particles having an average primary particle size of 50 to 500 nm and a bulk density of 0.3 g / cm ³ or more are externally added to the surface of the toner base particles. A developer for use in the developing device according to any one of claims 1 to 12 or the image forming apparatus according to any one of claims 13 to 18.
A developer comprising the carrier according to claim 19 and the toner according to any one of claims 20 to 22.

Images