JP2008116638A - Toner, developer, image forming apparatus and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner capable of keeping image density on development constant over a long period of time and keeping a stable charge amount over a long period of time, a developer, an image forming apparatus and a process cartridge using the same. <P>SOLUTION: The toner includes at least inorganic fine particles, has a variation of charge of ≤0% and is used in a developing device 4 in which three developer conveyance passages comprising a recovery conveyance passage 7, a supply conveyance passage 9 and a stirring conveyance passage 10 are parted from each other by partition members 133, 134, the stirring conveyance passage 10 and the recovery conveyance passage 7 are on the same level, the supply conveyance passage 9 is located above the other two developer conveyance passages, and toner is replenished to these developer conveyance passages. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing toner and developer, an image forming apparatus, and a process cartridge using the same.

  Conventionally, in a developing device using a two-component developer composed of toner and a magnetic carrier, the developer in the magnetic brush developing device is smoothly circulated, and a magnetic brush with a uniform toner density that is always stable on the developer carrier. In order to form the developer, a transport path for supplying the developer to the developing roller as a developer carrying member and a transport path for stirring the developer are provided separately, and the developer is transported in the opposite direction by the two transport paths. Thus, the developer is circulated.

  For example, in the developing device 54 shown in FIG. 5, a conveyance path for supplying the developer to the developing roller 55 and a conveyance path for collecting the developer that has been supplied to the developing roller and passed through the development area are common. Therefore, there is a problem that the toner concentration of the developer supplied to the developing roller 55 decreases toward the downstream side in the conveying direction of the conveying path that supplies the developing roller 55. When the toner density supplied to the developing roller 55 is lowered, the image density during development is also lowered.

JP-A-5-333691 JP 2002-365909 A Japanese Patent No. 3127594 (FIG. 1) JP-A-11-167260 (FIG. 1)

  In Patent Document 1, a first agitation chamber 125 including a first auger that conveys developer in a fixed direction at a position where the developer can be supplied to the developing roll in the developing device, and the first agitation chamber. And a second agitating chamber provided with a second auger that conveys developer in the opposite direction to the first auger, and the first agitating chamber and the second agitating chamber are separated by a partition wall. A developer circulation method is described in which the developer is partitioned and communicated at both ends, and the developer is conveyed so as to circulate in the two stirring chambers. However, in this developing apparatus, when the developer is conveyed by the first auger and the second auger so as to circulate, the developer is smoothly transferred from the lower stirring chamber to the upper stirring chamber. The developer is deposited near the end of the lower stirring chamber, and the developer is insufficiently stirred in the deposited portion, and the developer having a low toner density after passing through the developing region is supplied to the developing roll again. Since the toner is conveyed to the developing region, the toner concentration in the developer on the surface of the developing roll becomes non-uniform in the axial direction of the developing roll, and there is a problem that uneven density tends to occur in the image.

  In Patent Document 2, in order to prevent the developer from being deposited as described above, a developer carrying body that carries the developer to the development area facing the image carrying body for development, and a developer that rotates by rotating. A partition having first and second at least two transport portions provided with a transport member for transporting along the axial direction of the developer carrier, wherein the first and second transport portions have a circulation port. In the developing device that is arranged in the vertical direction through the circulation port and in which the developer is circulated through the circulation port, the first conveyance located above the second conveyance unit located below the first conveyance It is described that scooping means for scooping up the developer guided from the second transport unit to the first transport unit is provided in a circulation port portion that guides the developer to the part.

The developing device described in Patent Document 3 is shown in FIG.
The developing device 154 shown in FIG. 6 includes a second auger 158, a supply conveyance path 159 for supplying the developer to the developing roller 155, and a first auger 156, and collects the developer that has passed through the developing region. A collection conveyance path 157 is provided separately.

  In such a developing device 154, the developed developer is sent to the recovery conveyance path 157, and thus does not enter the supply conveyance path 159. As a result, the toner concentration of the developer supplied to the developing roller 155 is constant without changing the toner concentration of the developer in the supply conveyance path 159.

  However, since the developer sent to the collection conveyance path 157 is immediately supplied to the supply conveyance path 159, even if the toner is replenished and the toner concentration is kept properly, the stirring is insufficient, and the image during development There is a problem that non-uniform density and density decrease occur. Such a problem becomes more conspicuous as an image having a high printing rate in which the toner concentration of the collected developer is lowered.

Next, a developing device described in Patent Document 4 is shown in FIG.
The developing device 254 shown in FIG. 7 also includes a supply conveyance path 259 that includes a second auger 258 and supplies the developer to the developing roller 255, and a first auger 256, and collects the developer that has passed through the developing region. The conveyance path 257 is provided separately. Further, the developer is transported in the direction opposite to the supply transport path 259 while stirring the developer transported to the most downstream side of the supply transport path 259 and the recovered developer transported to the most downstream side of the recovery transport path 259. A stirring conveyance path 260 provided with a third auger 261 is provided.

  In such a developing device 254, the developed developer is sent to the collection conveyance path 257, and thus does not enter the supply conveyance path 259. As a result, the toner concentration of the developer supplied to the developing roller 255 becomes constant without changing the toner concentration of the developer in the supply conveyance path 259.

  Further, since the developer is not supplied immediately to the supply conveyance path 259 but is stirred in the agitation conveyance path 260 and then supplied to the supply conveyance path 259, the developer in a sufficiently agitated state is removed. It can supply to a supply conveyance path. As a result, it is possible to prevent non-uniform image density and lowering of image density during development, which are problems of the developing device 154 described with reference to FIG.

  However, the developing device 254 described in Patent Document 4 has a long screw path, and in order to deliver the developer from the agitating / conveying path 260 to the supply / conveying path 259 vertically above, developing is performed in the downstream portion of the agitating / conveying path 260. The developer is retained, the excessive developer is supplied, and the developer is raised by being pushed in by the third auger 261. Therefore, the stress on the developer is very large. For this reason, the staying toner deteriorates quickly, and problems such as scattering and background contamination due to deteriorated toner occur during long-term running.

  The present invention has been made in view of the above problems, and an object thereof is to maintain a constant image density during development over a long period of time and to maintain a stable charge amount over a long period of time. Another object is to provide a toner, a developer, an image forming apparatus, and a process cartridge using the same.

  As a result of diligent investigations, the present inventors have found that the difference between the initial charge amount and the charge amount with time when the toner and the carrier are mixed greatly affects the maintenance of a stable charge amount over a long period of time. Was completed.

That is, in order to achieve the above object, the present invention carries a two-component developer composed of a magnetic carrier and a toner on the surface, rotates, and rotates on the surface of the latent image carrier at a location facing the latent image carrier. A developer carrier for supplying toner to the latent image and developing the developer, and a developer supply / conveying member for conveying the developer along the axial direction of the developer carrier and supplying the developer to the developer carrier; The developer recovered from the developer carrier after passing through the developer supply conveyance path provided and the portion facing the latent image carrier along the axial direction of the developer carrier, and The developer collecting and conveying path provided with a developer collecting and conveying member that conveys in the same direction as the developer supply and conveying member, and the developer collecting and conveying path that is not used for development and conveyed to the most downstream side in the conveying direction of the developer supplying and conveying path Excess developer and the transport direction of the developer recovery transport path recovered from the developer carrier The developer supplied and transported to the most downstream side of the developer is supplied and transported along the axial direction of the developer carrying member and while stirring the excess developer and the recovered developer. A developer agitating and conveying member that conveys the developer in a direction opposite to the member, and having a developer agitating and conveying path for supplying the developer to the developer supply and conveying path, the developer collecting and conveying path, and the developer supply The three developer transport paths including the transport path and the developer stirring transport path are each partitioned by a partition member, and the developer stirring transport path and the developer recovery transport path are provided at substantially the same height. The developer supply transport path is a toner that is provided so as to be positioned above the other two developer transport paths, and contains at least inorganic fine particles used in a developing device that replenishes toner in the developer transport path. The charge fluctuation rate represented by the following formula is 0% or less It proposes a toner for developing electrostatic images, wherein Rukoto.
Charge fluctuation rate (%) = (Q15−Q600) / {(Q15 + Q600) / 2} × 100
Q15: Charge amount of developer stirred for 15 seconds using mag roll Q600: Charge amount of developer stirred for 10 minutes using mag roll

The present invention is effective when the charge fluctuation rate is -15% or less.
Furthermore, the present invention is effective when the charge fluctuation rate is −30% or less.
Furthermore, the present invention is effective when it contains at least silica and titanium oxide as inorganic fine particles.

Furthermore, the present invention is effective when the content of titanium oxide in the inorganic fine particles is 0.5 parts by weight or more.
Furthermore, the present invention is effective when the volume average particle diameter DV is 2 to 6 μm.

  In order to achieve the above object, the present invention includes a toner composed of the electrostatic image developing toner according to any one of claims 1 to 6 and a carrier composed of magnetic particles. Propose a developer.

The present invention is effective when the toner concentration (wt%) in the developer is 4 to 10%.
Furthermore, in order to achieve the above object, the present invention carries a two-component developer comprising a magnetic carrier and a toner on the surface and rotates the surface of the latent image carrier at a position facing the latent image carrier. A developer carrying member for developing the latent image by supplying toner, and a developer supply carrying member for carrying the developer along the axial direction of the developer carrying member and supplying the developer to the developer carrying member The developer recovered from the developer carrying body after passing through the developer supply conveyance path provided with the latent image carrying body, and along the axial direction of the developer carrying body, and A developer collecting and conveying path having a developer collecting and conveying member that conveys in the same direction as the developer supplying and conveying member, and the developer collecting and conveying path that is not used for development and conveyed to the most downstream side in the conveying direction of the developer supplying and conveying path. Excess developer and the transport method of the developer recovery transport path recovered from the developer carrier The developer supplied and transported to the most downstream side of the developer is supplied and transported along the axial direction of the developer carrying member and while stirring the excess developer and the recovered developer. A developer agitating and conveying member that conveys the developer in a direction opposite to the member, and having a developer agitating and conveying path for supplying the developer to the developer supply and conveying path, the developer collecting and conveying path, and the developer supply The three developer transport paths including the transport path and the developer stirring transport path are each partitioned by a partition member, and the developer stirring transport path and the developer recovery transport path are provided at substantially the same height. 9. The developing device according to claim 1, wherein the developer supply conveyance path is provided so as to be positioned above the other two developer conveyance paths, and toner is supplied to the developer conveyance path. An image forming apparatus using the toner or developer is proposed.

Furthermore, in order to achieve the above object, the present invention is a process in which a photosensitive member and at least one unit selected from a charging unit, a developing unit, and a cleaning unit are integrally supported and detachable from an image forming apparatus main body. In the cartridge, the developing means includes a toner, and the toner rotates on the surface carrying the two-component developer comprising the magnetic carrier and the toner according to claim 1 and faces the latent image carrier. A developer carrying member for supplying toner to the latent image on the surface of the latent image carrying member and developing the developer, and transporting the developer along the axial direction of the developer carrying member. A developer supply / conveying path having a developer supply / conveyance member for supplying the developer, and the developer recovered from the developer carrier after passing through a portion facing the latent image carrier. Along the axial direction of the carrier and the developer A developer collecting and conveying path having a developer collecting and conveying member that conveys in the same direction as the supply and conveying member, and an excess developer that is not used for development and is conveyed to the most downstream side in the conveying direction of the developer supply and conveying path And the supply of the recovered developer recovered from the developer carrier and transported to the most downstream side in the transport direction of the developer recovery transport path, along the axial direction of the developer carrier, and A developer agitating and conveying member that conveys the excess developer and the recovered developer in a direction opposite to the developer supplying and conveying member while stirring the developer, and supplying the developer to the developer supplying and conveying path A developer transport path, the developer supply transport path, and the developer agitation transport path, each of which is partitioned by a partition member, and the developer agitation transport path And the developer recovery conveyance path are provided at substantially the same height. The developer supply transport path is a toner that is provided so as to be positioned above the other two developer transport paths, and contains at least inorganic fine particles used in a developing device that replenishes toner in the developer transport path. Thus, a process cartridge is proposed which uses toner for developing an electrostatic image having a charge fluctuation rate represented by the following formula of −20% or less.
Charge fluctuation rate (%) = (Q15−Q600) / {(Q15 + Q600) / 2} × 100
Q15: Charge amount of developer stirred for 15 seconds using mag roll Q600: Charge amount of developer stirred for 10 minutes using mag roll

  According to the present invention, even if there is an increase in stress in the developing conveyance path, it is possible to keep the charge amount constant even after a long run. Furthermore, even if the toner is deteriorated due to stress, problems such as the scattering of the deteriorated toner and background stains do not occur, and there is an excellent effect that the life of the developer is extended and the image deterioration is small even after long-term use.

  Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a tandem type color laser copying machine (hereinafter simply referred to as “copying machine”) in which a plurality of photoconductors are arranged in parallel will be described.

  FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment. The copier includes a printer unit 100, a paper feeding device 200 on which the printer unit 100 is placed, a scanner 300 fixed on the printer unit 100, and the like. An automatic document feeder 400 fixed on the scanner 300 is also provided.

  The printer unit 100 forms an image composed of four sets of process cartridges 18Y, 18M, 18C, and 18K for forming an image of each color of yellow (Y), magenta (M), cyan (C), and black (K). A unit 20 is provided. Y, M, C, and K attached to the numbers of the respective symbols indicate members for yellow, magenta, cyan, and black (the same applies hereinafter). In addition to the process cartridges 18Y, 18M, 18C, and 18K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a resist roller pair 49, a belt fixing type fixing device 25, and the like are disposed. .

  The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of a photoreceptor to be described later with laser light based on image data.

The process cartridges 18Y, 18M, 18C, and 18K include a drum-shaped photosensitive member 1, a charger, a developing device 4, a drum cleaning device, a static eliminator, and the like.
Hereinafter, the yellow process cartridge 18 will be described.

  The north surface of the photoreceptor 1Y is uniformly charged by a charger as charging means. The surface of the photoreceptor 1 </ b> Y that has been subjected to charging processing is irradiated with laser light that has been modulated and deflected by the optical writing unit 21. Then, the potential of the irradiation part (exposure part) is attenuated. By this attenuation, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y as developing means to become a Y toner image.

  The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device.

  In the Y process cartridge 18Y, the photoconductor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charger and returns to the initial state. The series of processes as described above is the same for the other process cartridges (18M, C, K).

Next, the intermediate transfer unit will be described.
The intermediate transfer unit 17 includes an intermediate transfer belt 110, a belt cleaning device 90, and the like. Further, it also includes a tension roller 14, a driving roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K.

  The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14. Then, it is endlessly moved clockwise in the drawing by the rotation of the driving row 15 driven by a belt driving motor (not shown).

  The four primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive primary transfer bias from a power source (not shown). Further, the intermediate transfer belt 110 is pressed toward the photoreceptors 1Y, 1M, 1C, and 1K from the inner peripheral surface side to form primary transfer nips. In each primary transfer nip, a primary transfer electric field is formed between the photosensitive member and the primary transfer bias roller due to the influence of the primary transfer bias.

  The above-described Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 due to the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) that is a multiple toner image is formed on the intermediate transfer belt 110.

  The four-color toner image superimposed and transferred onto the intermediate transfer belt 110 is secondarily transferred onto a transfer sheet (not shown) as a recording sheet at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 90 that sandwiches the belt with the driving roller 15 on the left side in the drawing.

Next, the secondary transfer device 22 will be described.
Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 is moved endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23 arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the secondary transfer backup roller 16 of the intermediate transfer unit 17. It is out. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one stretching roller 23 by a power source (not shown). By applying this secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is electrostatically moved from the belt side toward the one stretching roller 23 side in the secondary transfer nip. A next transfer electric field is formed. The transfer paper fed into the secondary transfer nip so as to synchronize with the four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 to be described later has four colors affected by the secondary transfer electric field and nip pressure. The toner image is secondarily transferred. Instead of the secondary transfer method in which the secondary transfer bias is applied to one of the stretching rollers 23 as described above, a charger for charging the transfer paper in a non-contact manner may be provided.

  In the paper feeding device 200 provided at the lower part of the copying machine main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and accommodated in a bundle of sheets are arranged so as to overlap in the vertical direction. Has been. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 46.

  The paper feed path 46 that receives the transfer paper fed from the paper feed cassette 44 has a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the path. Then, the transfer sheet is conveyed toward a registration roller pair 49 provided in the conveyance path 48. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the transfer paper can be brought into close contact with the four-color toner image at the secondary transfer nip. Thereby, in the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, it is secondarily transferred onto the transfer paper and becomes a full color image on the white transfer paper. The transfer paper on which the full-color image is formed in this manner exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and then is sent from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that moves the fixing belt 26 endlessly while being stretched by two rollers, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source (not shown) inside, and pressurizes the fixing belt 26 by the generated heat. The pressed fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.

  The transfer paper that has been subjected to the fixing process in the fixing device 25 is stacked on a stack portion 57 that protrudes from the left side plate in the drawing of the printer housing or forms a toner image on the other surface. Therefore, it is returned to the secondary transfer nip described above.

  When a document (not shown) is copied, for example, a bundle of sheet documents is set on the document table 30 of the automatic document feeder 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the automatic document feeder 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the single-bound original is pressed by the closed automatic document feeder 400.

  When a copy start switch (not shown) is pressed after the document is set in this way, the document reading operation by the scanner 300 starts. However, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 automatically moves the sheet document to the contact glass 32 prior to the document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such document reading operation, each device in each process cartridge (18Y, M, C, K), the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 start driving. Then, based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, K toner images are formed on the respective photosensitive members (40Y, M, C, K). Is formed. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed transfer sheets are separated one by one by the separation roller 45 and enter the reverse feeding path 46, and then conveyed toward the secondary transfer nip by the conveyance roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the transfer paper on the manual feed tray 51, the separation roller 52 separates the transfer paper one by one and feeds it to the manual feed path 53 of the printer unit 100. Make paper.

  In the case of forming another color image composed of two or more colors of toner, the copying machine stretches the intermediate transfer belt 110 so that the upper stretched surface thereof is substantially horizontal, Photoconductors (1Y, M, C, K). On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted to the lower left in the drawing by a mechanism (not shown) and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, the driving of not only the photoconductor but also the developing device is stopped to prevent unnecessary consumption of the photoconductor and the developer.

  The copying machine includes a control unit (not shown) configured by a CPU or the like that controls the following devices in the copying machine, and an operation display unit (not shown) configured by a liquid crystal display, various key buttons, and the like. The operator sends a command to the control unit by a key input operation on the operation display unit, so that one of the three modes is selected from the three-sided print mode, which is a mode for forming an image only on one side of the transfer paper. You can choose one. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

  FIG. 2 is an enlarged configuration diagram showing the developing device 4 and the photoreceptor 1 provided in one of the four process cartridges 18 (Y, M, C, K). The four process cartridges 18 (Y, M, C, K) have substantially the same configuration except that the colors of the toners to be handled are different from each other. Therefore, Y, M, C denoted by “4” in FIG. , K are omitted.

  As shown in FIG. 2, the surface of the photosensitive member 1 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. The charged surface of the photoreceptor 1 is supplied with toner from the developing device 4 to a latent image on which an electrostatic latent image is formed by laser light emitted from an exposure device (not shown), thereby forming a toner image.

  The developing device 4 has a developing roller 5 as a developer carrying member for supplying toner to the latent image on the surface of the photoreceptor 1 while moving the surface in the direction of arrow I in the drawing. Further, a supply screw 8 is provided as a developer supply / conveying member that conveys the developer in the depth direction of FIG. 2 while supplying the developer to the developing roller 5.

  A developing doctor 12 as a developer regulating member for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided on the downstream side of the surface moving direction from the portion facing the supply screw 8 of the developing roller 5. ing.

  The developed developer that has passed through the developing section is collected downstream from the developing section, which is the facing portion of the developing roller 5 with respect to the photoconductor 1, and the collected developer is collected in the same direction as the supply screw 8. A recovery screw 6 is provided as a developer recovery / conveying member. A supply conveyance path 9, which is a developer supply conveyance path provided with a supply screw 8, is in the lateral direction of the developing roller 5, and a recovery conveyance path 7 as a developer collection conveyance path provided with a collection screw 6 is below the development roller 5. It is installed side by side.

  The developing device 4 is provided with an agitation conveyance path 10 that is a developer agitation conveyance path in parallel with the recovery conveyance path 7 below the supply conveyance path 9. The agitating and conveying path 10 includes an agitating screw 11 as a developer agitating and conveying member that conveys the developer to the front side in the figure, which is in the opposite direction to the supply screw 8 while agitating the developer.

  The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. In the first partition wall 133, the supply conveyance path 9 and the agitation conveyance path 10 are partitioned at both ends on the front side and the back side in the drawing, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. is doing.

  Note that the supply conveyance path 9 and the recovery conveyance path 7 are both partitioned by the first partition member 133, but an opening is provided in the first partition wall 133 where the supply conveyance path 9 and the agitation conveyance path 7 are partitioned. Absent.

  Further, the two conveyance paths of the stirring conveyance path 10 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the figure, and the agitation transport path 10 and the collection transport path 7 communicate with each other.

  The supply screw 8, the recovery screw 6 and the stirring screw 11, which are developer conveying members, are made of resin screws, and each screw diameter is φ18 [mm], the screw pitch is 25 [mm], and the rotation speed is about 600 [rpm]. ] Is set.

  The developer thinned by the developing doctor 12 made of stainless steel on the developing roller 5 is transported to a developing area which is a portion facing the photosensitive member 1 for development. The surface of the developing roller 5 is V-groove or sandblasted and is made of an Al [aluminum] element tube with a diameter of 25 [mm], and the gap between the developing doctor 12 and the photoreceptor 1 is about 0.3 [mm]. .

  The developer after the development is collected in the collection conveyance path 7, conveyed to the front side of the cross section in FIG. 2, and to the agitation conveyance path 10 through the opening of the first partition wall 133 provided in the non-image area portion. Developer is transferred. In addition, toner is supplied to the stirring and conveying path 10 from a toner replenishing port provided on the upper side of the stirring and conveying path 10 in the vicinity of the opening of the first partition wall 133 on the upstream side in the developer conveying direction in the stirring and conveying path 10.

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 3 is a perspective sectional view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer.

4 is a schematic diagram of the flow of the developer in the developing device 4. Like FIG. 3, each arrow in the drawing indicates the moving direction of the developer.
In the supply conveyance path 9 that has been supplied with the developer from the agitation conveyance path 10, the developer is conveyed downstream in the conveyance direction of the supply screw 8 while supplying the developer to the developing roller 5. Then, the excess developer that is supplied to the developing roller 5 and is not used for development and is transported to the downstream end in the transport direction of the supply transport path 9 is supplied to the stirring transport path 10 from the opening of the first partition wall 133 (FIG. 4). Middle arrow E).

  The collected developer that is sent from the developing roller 5 to the collection conveyance path 7 and conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 is supplied to the stirring conveyance path 10 from the opening of the second partition wall 134. (Arrow F in FIG. 4).

  The agitating and conveying path 10 agitates the supplied surplus developer and the recovered developer, conveys the agitating screw 11 to the downstream side in the conveying direction, and conveys it to the upstream side in the conveying direction of the supplying screw 8. It is supplied to the supply conveyance path 9 from the opening part 133 (arrow D in FIG. 4).

  In the agitating and conveying path 10, the agitating screw 11 agitates and conveys the collected developer, the surplus developer, and the toner replenished as necessary in the transfer unit in the direction opposite to the developer in the collecting and conveying path 7 and the supply conveying path 9. . Then, the agitated developer is transferred to the upstream side in the conveyance direction of the supply conveyance path 9 communicating with the downstream side in the conveyance direction. A toner concentration sensor (not shown) is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner storage portion (not shown).

In the developing device 4 shown in FIG. 4, a supply conveyance path 9 and a collection conveyance path 7 are provided, and developer supply and collection are performed in different developer conveyance paths, so that the developed developer is supplied to the supply conveyance path 9. There is no contamination. Accordingly, it is possible to prevent the toner density of the developer supplied to the developing roller 5 from decreasing toward the downstream side of the supply conveyance path 9 in the conveyance direction. Further, since the recovery conveyance path 7 and the agitation conveyance path 10 are provided and the developer recovery and agitation are performed in different developer conveyance paths, the developed developer does not fall during the agitation. Therefore, since the sufficiently agitated developer is supplied to the supply conveyance path 9, it is possible to prevent the developer supplied to the agent supply conveyance path 9 from being insufficiently agitated. In this way, the toner density of the developer in the supply conveyance path 9 can be prevented from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred. Can be constant.

  As shown in FIG. 4, the developer moves from the lower part to the upper part of the developing device 4 only by the arrow D. The movement of the developer indicated by an arrow D is to push the developer by rotating the stirring screw 11 so that the developer is raised and supplied to the supply conveyance path 9.

  Such movement of the developer gives a great stress to the developer, and causes the embedded and free inorganic fine particles. The deteriorated toner has a reduced charging ability, and the replenishment toner having a high charging ability takes the charge amount. For this reason, the deteriorated toner is liberated in the developer, causing scattering and background staining.

  As described above, in the developing device having a structure for lifting the developer from below to above, the toner in the developer is deteriorated and the image quality is deteriorated accordingly. However, since the charging capability of the replenishing toner can be lowered and the charging capability can be maintained even when stress is applied, a decrease in the charge amount with time can be prevented. By preventing the charge amount from decreasing with time, it is possible to prevent image deterioration and always provide image quality free from uneven image density.

  In the developing device in which the function of supplying and collecting the developer is not separated, the replenished toner is conveyed to the developing unit without being sufficiently mixed with the carrier. For this reason, if the initial charge amount of the toner is not increased, toner scattering and soiling occur. In order to increase the initial charge amount, it is necessary to use a material having a charge column on the toner surface. However, since the toner is charged by friction, it is inevitable that the surface is scraped over time and the charging ability is lowered. For this reason, there has been no means for preventing the amount of charge from being taken away by a new replenishing toner having a high charging capability and causing the deteriorated toner to scatter or cause dirt. Therefore, it is difficult to extend the life of the developer, and there is a problem in maintaining image quality over a long period of time.

  Therefore, in the present invention, since the toner concentration at the replenishing port is lowered by using a developing device that separates the supply and recovery functions, the replenished toner is sufficiently agitated with the carrier. For this reason, even if the initial charge amount is not increased, it is sufficiently agitated and charged until it is conveyed to the development area. Therefore, it is not necessary to increase the initial charge amount, and the toner surface and the internal material can be made uniform. As a result, even if the surface of the toner is scraped over time, the charging ability does not change. Therefore, even when new toner is replenished, scattering of deteriorated toner and scumming are prevented. This makes it possible to maintain the image quality over a long period of time without replacing the developer even during long-term use.

  Q15 and Q600 in the present invention can be measured by the following method. First, a magnet is attached to the lower part of the roll mill container, which is a mag roll, and a stirring device comprising a sealed container that can be stirred while applying a load to the magnetic carrier of the developer in the container by the magnetic force of the magnet, 7 g of developer mixed with a toner coverage of 70% is put into the stirring device. Next, the developer is stirred for a predetermined time at a rotational speed of 280 rpm while applying a magnetic force of 1000 G. The charge amount of the developer after stirring is measured using a blow-off device, and the charge amount of the developer stirred for 15 seconds is defined as Q15, and the charge amount of the developer stirred for 10 minutes is defined as Q600. The blow-off device separates the carrier and the toner with air through a sieve, and charges Q (coulomb) held by the separated toner and the toner weight (g) that has been blown off using a Q meter and a precision balance. This is an apparatus for measuring and obtaining a charge amount Q / m (charge amount) per unit weight of toner.

  In the present invention, it is effective to externally add silica or titanium oxide as inorganic fine particles from the viewpoint of securing fluidity and charging ability. In particular, titanium oxide is desirably added in an amount of 0.5 parts by weight or more in order to ensure sufficient toner fluidity and to suppress an increase in toner charge amount. When the fluidity of the toner is poor, the fluidity of the developer is deteriorated, the toner is not sufficiently stirred, and problems such as toner scattering occur.

  In the present invention, it is desirable to use a toner having a small particle diameter. When small particle warp toner is used, the toner concentration can be lowered from the relationship of reducing the coverage and the amount of adhesion, which is expected to further improve scattering and soiling. In addition, in the case of a small particle size, there are concerns about spent on the carrier due to strong charging and scattering of replenishing toner due to excessive increase in the charge amount of the deteriorated toner, but in the present invention, since the charge amount is in a direction to be suppressed, These concerns are also eliminated. As a result, it is possible to obtain merits such as image quality improvement and toner yield improvement due to the small particle size.

EXAMPLES Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto (hereinafter, “parts” means “parts by weight”).
(Evaluation of two-component developer)

When evaluating an image with a two-component developer, a ferrite carrier having an average particle size of 35 μm coated with a silicone resin with an average thickness of 0.5 μm is used as follows, and toner 7 of each color is used with respect to 100 parts by weight of the carrier. The developer was prepared by uniformly mixing and charging the parts by weight using a tumbler mixer of the type in which the container rolls and stirs.
(Carrier production)

Core material Mn ferrite particles (weight average diameter: 35 μm) 5000 parts Coat material toluene 450 parts Silicone resin SR2400 (made by Toray Dow Corning Silicone, nonvolatile content 50%) 450 parts Aminosilane SH6020 (made by Toray Dow Corning Silicone) )
10 copies

10 parts of carbon black The above coating material is dispersed with a stirrer for 10 minutes to prepare a coating solution, and the coating solution and the core material are coated while forming a swirling flow having a rotating bottom plate disk and stirring blades in a fluidized bed. The coating liquid was put into a coating apparatus to be applied, and the coating liquid was applied onto the core material. The obtained coated material was baked in an electric furnace at 250 ° C. for 2 hours to obtain the carrier.
(Evaluation item)

Image Density Unevenness An image area ratio 5% chart continuous 300,000 sheet output durability test was performed using each toner, and image density unevenness after output was visually evaluated. The result. It shows in Table 2.

  ◎: No unevenness on the image, ○: Density unevenness slightly observed but no problem, △: Conspicuous density unevenness is slightly conspicuous, x indicates density outside the allowable range Unevenness is very noticeable.

-Developer life The image area ratio 5% chart continuous durability test was carried out using each toner, and the durability of the developer was evaluated. ◎: The image after output of 300,000 sheets is the same as the initial image, ○: The image after output of 300,000 sheets is somewhat deteriorated, △: Output 300,000 sheets, but the image is severely deteriorated, ×: 300,000 sheets It is necessary to change the developer before it becomes.

-Charging stability Using each toner, an image area ratio 5% chart continuous 300,000 sheet durability test was conducted, and the subsequent change in charge amount was evaluated. 1 g of developer was weighed and the change in charge amount was determined by the blow-off method. When the change in charge amount compared with the initial value was 5 μc / g or less, it was evaluated as ◯, when it was 10 μc / g or less, Δ when it exceeded 10 μc / g.

-Toner Scattering Using each toner, an image area ratio 5% chart continuous 300,000 sheet durability test was performed, and then the toner scattering state was evaluated. If there is no contamination inside the copier due to toner, ◎, slightly present, but no problem level for practical use, ◯, a large amount of scattering, △ a level where there is no problem on the image, a large amount of scattering on the image The level at which the problem occurred up to was marked with x.

-Background stain The image area ratio 5% chart continuous 300,000 sheet endurance test was carried out using each toner, and then the background stain on the white paper portion was evaluated. The blank image is stopped during development, the developer on the developed photoreceptor is tape transferred, and the difference from the image density of the untransferred tape is measured with a 938 spectrocytometer (manufactured by X-Rite). It was. The smaller the difference in image density, the better the background dirt. ◎ indicates ΔID of less than 0.01, ◯ indicates ΔID is 0.01 to 0.02, Δ indicates ΔID is 0.02 to 0.05, and X indicates ΔID is 0.05 or more.
(Manufacture of toner)

Synthesis of organic fine particle emulsion Production Example 1
In a reaction vessel equipped with a stir bar and a thermometer, 683 parts of water, 11 parts of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries), 166 parts of methacrylic acid, 110 butyl acrylate Parts and 1 part of ammonium persulfate were added and stirred at 3800 rpm for 30 minutes to obtain a white emulsion. The system was heated to raise the system temperature to 75 ° C. and reacted for 4 hours. Furthermore, 30 parts of a 1% ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 6 hours, and an aqueous dispersion of vinyl resin (methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt copolymer). [Fine particle dispersion 1] was obtained. The volume average particle diameter of [fine particle dispersion 1] measured with LA-920 was 110 nm. A portion of [Fine Particle Dispersion 1] was dried to isolate the resin component. The Tg of the resin was 58 ° C., and the weight average molecular weight was 130,000.

Preparation of aqueous phase Production Example 2
990 parts of water, 83 parts of [fine particle dispersion 1], 37 parts of a 48.3% aqueous solution of dodecyl diphenyl ether disulfonate (Eleminol MON-7: manufactured by Sanyo Chemical Industries) and 90 parts of ethyl acetate are mixed and stirred. A milky white liquid was obtained. This is designated as [Aqueous Phase 1].

Synthesis of low molecular weight polyester Production Example 3
In a reaction vessel equipped with a condenser, a stirrer and a nitrogen inlet tube, 229 parts of bisphenol A ethylene oxide 2-mole adduct, 529 parts of bisphenol A propylene oxide 3-mole adduct, 208 parts terephthalic acid, 46 parts adipic acid and dibutyl Add 2 parts of tin oxide, react at 230 ° C for 7 hours at normal pressure, and further react for 5 hours under reduced pressure of 10-15 mmHg, then add 44 parts of trimellitic anhydride to the reaction vessel at 180 ° C at normal pressure. By reacting for 3 hours, [low molecular weight polyester 1] was obtained. [Low molecular polyester 1] had a number average molecular weight of 2,300, a weight average molecular weight of 6,700, Tg of 43 ° C., and an acid value of 25.

Synthesis of Intermediate Polyester Production Example 4
In a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, 682 parts of bisphenol A ethylene oxide 2-mole adduct, 81 parts of bisphenol A propylene oxide 2-mole adduct, 283 parts of terephthalic acid, trimellitic anhydride 22 And 2 parts of dibutyltin oxide were added, reacted at 230 ° C. for 7 hours at normal pressure, and further reacted for 5 hours at a reduced pressure of 10 to 15 mmHg to obtain [Intermediate Polyester 1]. [Intermediate Polyester 1] had a number average molecular weight of 2200, a weight average molecular weight of 9700, Tg of 54 ° C., an acid value of 0.5, and a hydroxyl value of 52.

  Next, 410 parts of [Intermediate polyester 1], 89 parts of isophorone diisocyanate and 500 parts of ethyl acetate are placed in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe, and reacted at 100 ° C. for 5 hours. Polymer 1] was obtained. [Prepolymer 1] had a free isocyanate weight percentage of 1.53%.

Synthesis of ketimine Production Example 5
In a reaction vessel equipped with a stirrer and a thermometer, 170 parts of isophoronediamine and 75 parts of methyl ethyl ketone were charged and reacted at 50 ° C. for 4 and a half hours to obtain [ketimine compound 1]. The amine value of [ketimine compound 1] was 417.

Synthesis of master batch) (MB) Production Example 6
1200 parts of water, 540 parts of carbon black (made by Printex 35 Dexa) [DBP oil absorption = 42 ml / 100 mg, pH = 9.5] and 1200 parts of polyester resin are added and mixed with a Henschel mixer (made by Mitsui Mining Co., Ltd.). The mixture was kneaded at 130 ° C. for 1 hour using two rolls, rolled and cooled, and pulverized with a pulverizer to obtain [Masterbatch 1].

Production of oil phase Production Example 7
In a container equipped with a stir bar and a thermometer, 378 parts of [Low molecular polyester 1], 100 parts of Carnauba WAX, and 947 parts of ethyl acetate were charged, heated to 80 ° C. with stirring, and kept at 80 ° C. for 5 hours. It was cooled to 30 ° C at 1 hour. Next, 500 parts of [Masterbatch 1] and 500 parts of ethyl acetate were placed in a container and mixed for 1 hour to obtain [Raw material solution 1].

  [Raw Material Solution 1] 1324 parts were transferred to a container, and using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.), a liquid feeding speed of 1 kg / hr, a disk peripheral speed of 6 m / sec, and 0.5 mm zirconia beads were 80% by volume. Carbon black and WAX were dispersed under conditions of filling and 3 passes. Next, 1324 parts of a 65% ethyl acetate solution of [low molecular weight polyester 1] was added, followed by two passes with a bead mill under the above conditions to obtain [Pigment / WAX Dispersion 1]. The solid content concentration of [Pigment / WAX Dispersion 1] (130 ° C., 30 minutes) was 50%.

Emulsification ⇒ Desolvation Production Example 8
[Pigment / WAX Dispersion 1] 749 parts, [Prepolymer 1] 115 parts, [Ketimine Compound 1] 2.9 parts in a container and TK homomixer (manufactured by Tokushu Kika) at 5.000 rpm for 2 minutes After mixing, 1200 parts of [Aqueous Phase 1] was added to the container, and mixed with a TK homomixer at 13,000 rpm for 25 minutes to obtain [Emulsified Slurry 1].

[Emulsion slurry 1] was put into a container equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C for 8 hours, aging was carried out at 45 ° C for 7 hours to obtain [Dispersion slurry 1].
Cleaning ⇒ drying

Production Example 9
[Dispersion Slurry 1] After filtering 100 parts under reduced pressure,
A: 100 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
B: 100 parts of a 10% aqueous sodium hydroxide solution was added to the filter cake of A, mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure.
100 parts of 10% hydrochloric acid was added to the filter cake of C: B, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
D: C 300 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered twice to obtain [filter cake 1].

[Filter cake 1] was dried at 45 ° C. for 48 hours in a circulating dryer. Thereafter, sieved with a mesh of 75 μm, [toner base particle 1] was obtained.

  The above [Toner Base Particle 1] is cut into fine powder and coarse powder, and the mixture is stirred and mixed so that the silica fine particle is 1.5 parts by weight and the titanium oxide fine particle is 0.5 parts by weight based on 100 parts by weight of the toner base. And used as an electrophotographic toner.

(Comparative Example 1)
[Toner base particle 2] produced by adding a fluorine-based hydrophobizing agent during the preparation of the toner base particles was cut into fine powder and coarse powder, and 1.5 parts by weight of silica fine particles were added to 100 parts by weight of the toner base. The titanium oxide fine particles were stirred and mixed so as to be 0.5 parts by weight, and used as an electrophotographic toner.

  The [Toner Base Particle 1] is finely divided and coarse powder is cut, and the mixture is stirred and mixed so that 100 parts by weight of the toner base is 0.5 parts by weight of silica fine particles and 1.0 part by weight of titanium oxide fine particles. And used as an electrophotographic toner.

(Comparative Example 2)
The above [Toner Base Particle 1] was cut into fine powder and coarse powder, and the mixture was stirred and mixed so that the silica fine particle was 1.5 parts by weight with respect to 100 parts by weight of the toner base, and used as an electrophotographic toner.

  The stirring time after adding the aqueous phase during the emulsification of the toner base particles was set to 40 minutes. [Toner base particles 3] was finely divided and coarse powder was cut, and silica fine particles were added to 100 parts by weight of the toner base. The mixture was stirred and mixed to 1.5 parts by weight and titanium oxide fine particles to 0.5 parts by weight, and used as an electrophotographic toner.

The physical properties of the obtained toner are shown in Table 1, and the evaluation results are shown in Table 2.
Among the physical properties of the toner, the charge fluctuation rate is calculated based on the following formula by measuring Q15 and Q600 in the developers of the above-described examples and comparative examples.
Charge fluctuation rate (%) = (Q15−Q600) / {(Q15 + Q600) / 2} × 100

  As is apparent from Table 2, it can be seen that the smaller the fluctuation rate, that is, the greater the minus, the better the evaluation items for image density unevenness, developer life, charging stability, toner scattering, and background stain. This is because when the charge fluctuation rate is positive, the newly replenished toner has a stronger ability to acquire electrons than the toner deteriorated by stirring for a long time. When the charge fluctuation rate is positive, a high charge amount is obtained at the initial stage of stirring. Therefore, the deteriorated toner loses the charge amount, and problems such as background contamination and toner scattering occur.

  For this reason, it is preferable that the charge fluctuation rate is negative. In particular, in the developing device 4 having three conveyance paths, it takes a long time for the supplied toner to reach the developing roller 5 and is sufficiently stirred. . For this reason, even if the charge amount at the initial stage of stirring is low, it is difficult for dirt and scattering to occur. On the other hand, once the deteriorated toner loses the charge amount, it becomes difficult to be charged again. Therefore, it is necessary to make the charge amount at the initial stage of stirring as low as possible. Therefore, the charge fluctuation rate is more preferably negative. If the charge fluctuation rate is −15% or less, problems are hardly caused in the evaluation items, and if the charge fluctuation rate is −30% or less, the evaluation items are good.

1 is a schematic configuration diagram of a copier according to an embodiment. It is a schematic block diagram of a developing device and a photoreceptor. It is a perspective sectional view of the developing device for explaining the flow of the developer. It is a schematic diagram of the flow of the developer in the developing device. It is a schematic block diagram of a conventionally known developing device. 1 is a schematic configuration diagram of a developing device described in Patent Document 1. FIG. 10 is a schematic configuration diagram of a developing device described in Patent Document 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing apparatus 5 Developing roller 6 Collection screw 7 Collection conveyance path 8 Supply screw 9 Supply conveyance path 10 Stirring conveyance path 11 Stirring screw 12 Developing doctor 110 Intermediate transfer belt 133 First partition wall 134 Second partition wall

Claims (10)

A developer that carries a two-component developer composed of a magnetic carrier and a toner on the surface, rotates, supplies toner to the latent image on the surface of the latent image carrier, and develops it at a location facing the latent image carrier. A carrier,
A developer supply transport path including a developer supply transport member that transports the developer along the axial direction of the developer support and supplies the developer to the developer support;
The developer recovered from the developer carrier after passing through the portion facing the latent image carrier is along the axial direction of the developer carrier and in the same direction as the developer supply / conveying member. A developer recovery transport path including a developer recovery transport member for transporting
Excess developer transported to the most downstream side in the transport direction of the developer supply transport path without being used for development, and to the most downstream side in the transport direction of the developer collection transport path recovered from the developer carrier Receiving supply of the collected developer that has been conveyed, along the axial direction of the developer carrier, and in the direction opposite to the developer supply and conveying member while stirring the excess developer and the collected developer A developer agitating and conveying member for conveying the developer to the developer supplying and conveying path, and a developer agitating and conveying path for supplying the developer to the developer supplying and conveying path,
Three developer transport paths including the developer recovery transport path, the developer supply transport path, and the developer agitation transport path are each partitioned by a partition member, and the developer agitation transport path, the developer recovery transport path, Are provided at substantially the same height, and the developer supply conveyance path is provided above the other two developer conveyance paths, and a developer is supplied to the developer conveyance path. A toner containing at least inorganic fine particles used,
A toner for developing an electrostatic charge image, wherein the charge fluctuation rate represented by the following formula is 0% or less.
Charge fluctuation rate (%) = (Q15−Q600) / {(Q15 + Q600) / 2} × 100
Q15: Charge amount of developer stirred for 15 seconds using mag roll Q600: Charge amount of developer stirred for 10 minutes using mag roll   The toner for developing an electrostatic charge image according to claim 1, wherein the charge fluctuation rate is −15% or less.   The toner for developing an electrostatic charge image according to claim 1, wherein the charge fluctuation rate is −30% or less.   The electrostatic image developing toner according to claim 1, wherein the inorganic fine particles contain at least silica and titanium oxide.   5. The electrostatic image developing toner according to claim 1, wherein the content of titanium oxide in the inorganic fine particles is 0.5 parts by weight or more.   6. The electrostatic charge image developing toner according to claim 1, wherein the volume average particle diameter DV is 2 to 6 [mu] m.   A two-component electrostatic charge image developing developer comprising the electrostatic charge image developing toner according to claim 1 and a carrier comprising magnetic particles.   8. The developer for developing an electrostatic charge image according to claim 7, wherein a toner concentration (wt%) in the developer is 4 to 10%. A developer that carries a two-component developer composed of a magnetic carrier and a toner on the surface, rotates, supplies toner to the latent image on the surface of the latent image carrier, and develops it at a location facing the latent image carrier. A carrier, a developer supply transport path including a developer supply transport member that transports the developer along the axial direction of the developer support and supplies the developer to the developer support, and the latent image. The developer recovered from the developer carrier after passing through the portion facing the carrier is transported along the axial direction of the developer carrier and in the same direction as the developer supply and transport member. A developer collecting and conveying path provided with a developer collecting and conveying member; an excess developer that is not used for development and conveyed to the most downstream side in the conveying direction of the developer supply and conveying path; and collected from the developer carrier Supply with the recovered developer transported to the most downstream side in the transport direction of the developer recovery transport path A developer agitating / conveying member that conveys in the direction opposite to the developer supply / conveying member while stirring the surplus developer and the recovered developer along the axial direction of the developer carrying member; A developer agitation transport path for supplying the developer to the developer supply transport path, and the developer recovery transport path, the developer supply transport path, and the developer agitation transport path. Each of the transport paths is partitioned by a partition member, and the developer agitation transport path and the developer recovery transport path are provided at substantially the same height, and the developer supply transport path is the same as the other two developer transport paths. In the developing device provided so as to be positioned above and supplying toner to the developer transport path,
An image forming apparatus using the toner or developer according to claim 1. In a process cartridge that integrally supports at least one unit selected from a photosensitive member and a charging unit, a developing unit, and a cleaning unit and is detachable from the main body of the image forming apparatus, the developing unit includes toner. The toner is rotated by carrying the two-component developer comprising the magnetic carrier and the toner according to claim 1 on the surface, and the latent image on the surface of the latent image carrier is opposed to the latent image carrier. A developer carrying member for supplying the toner to the developer and developing the developer carrying member along the axial direction of the developer carrying member, and supplying the developer to the developer carrying member. The developer recovered from the developer carrying member after passing through the developer supply / conveying path and the portion facing the latent image carrier along the axial direction of the developer carrying member and the development Developer collection and transport in the same direction as the developer supply and transport member A developer recovery conveyance path provided with a material, an excess developer that is not used for development and conveyed to the most downstream side in the conveyance direction of the developer supply conveyance path, and the developer recovered from the developer carrier. The supply of the recovered developer transported to the most downstream side in the transport direction of the recovery transport path is received, and the surplus developer and the recovered developer are stirred along the axial direction of the developer carrier. A developer agitating and conveying member that conveys the developer in a direction opposite to the developer supply and conveying member, and a developer agitating and conveying path for supplying the developer to the developer supplying and conveying path, and the developer collecting and conveying The three developer transport paths including the developer path, the developer supply transport path, and the developer stirring transport path are each partitioned by a partition member, and the developer stirring transport path and the developer recovery transport path are substantially the same height. The developer supply transport path is provided above the other two developer transport paths. Is a toner containing at least inorganic fine particles used in a developing device that is replenished with toner in the developer conveyance path, and the charge fluctuation rate represented by the following formula is -20% or less A process cartridge comprising: an electrostatic charge image developing toner.
Charge fluctuation rate (%) = (Q15−Q600) / {(Q15 + Q600) / 2} × 100
Q15: Charge amount of developer stirred for 15 seconds using mag roll Q600: Charge amount of developer stirred for 10 minutes using mag roll

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