JP4821831B2 - Developing device and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a composite machine thereof, and a developing device used for developing an electrostatic latent image formed on an image carrier in such an image forming apparatus. In particular, when an image is formed in an image forming apparatus using a developing device using a developer containing a toner and a carrier, even if the image forming speed is increased, the developing device includes the toner and the carrier. Even when the developer is sufficiently mixed and stirred so that a new toner or a developer containing a large amount of new toner is supplied, the supplied toner is appropriately charged and the developer in the developing device is also charged. This is characterized in that unevenness in the toner density in the toner is prevented and appropriate development can be performed stably.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, printers, facsimiles, and composite machines thereof, toner is supplied from a developing device to an electrostatic latent image formed on an image carrier such as a photoconductor, and the image is carried. The electrostatic latent image formed on the body is developed.

  As such a developing device, a one-component developing type developing device using only toner as a developer and a two-component developing type developing device using a developer containing toner and a carrier are known. The two-component developing system using a developer containing a toner and a carrier is excellent in that the toner is quickly and appropriately charged to form a high-speed image.

  Here, in a two-component developing type developing device using a developer containing toner and a carrier, the developer is generally conveyed while being mixed and stirred by a stirring and conveying member in a developer conveying portion in the developing device. The toner is brought into contact with the carrier to charge the toner, and the developer thus charged with the toner is led to a developer transport supply unit that supplies the developer carrying member, and the developer transport supply unit The developer is supplied to the developer carrying member, and toner is supplied from the developer carrying member to the electrostatic latent image formed on the image carrying member for development. The developer is transported while being mixed and stirred by a stirring transport member, and the developer is circulated between the developer transport section and the developer transport supply section.

  When toner is supplied from the developer carrier to the electrostatic latent image formed on the image carrier as described above and development is performed, the density of the toner in the developer gradually decreases, and an image is formed. Therefore, when the toner concentration in the developer decreases to some extent, the developer is replenished with a new toner or a developer containing a lot of new toner.

  Here, the new toner replenished in this way is in an uncharged state, and the toner thus replenished is supplied to the developer carrying member from the developer transport supply unit in a state where it is not sufficiently charged. If the toner is used in a toner, there is a problem that the toner is scattered or fog is generated in the formed image. Further, only the toner concentration of the developer in the portion where the toner is replenished becomes high, and the development is performed. There is a problem in that unevenness occurs in the toner density in the developer in the apparatus, resulting in uneven density in the formed image.

  For this reason, conventionally, as disclosed in Patent Document 1, a developer conveying and supplying unit that supplies developer to the developer carrying member while agitating and conveying the developer by the agitating and conveying member, and mixing and agitating the developer by the agitating and conveying member It has been proposed to increase the length of the developer in the transport direction with the developer transport section to be transported while increasing the distance to transport the developer while mixing and stirring to sufficiently charge the replenished toner. ing.

  However, toner is replenished even when the length of the developer conveyance direction in the developer conveyance supply unit and the developer conveyance unit is increased in this way and the distance in which the developer is conveyed while being mixed and agitated is increased. Only the toner density of the developer in the exposed area becomes high, and unevenness in the toner density in the developer in the developing device cannot be sufficiently prevented from occurring in the formed image. .

  Further, in recent years, it has been required to increase the image forming speed in the image forming apparatus and perform image formation at high speed.

  In the case where image formation is performed at such a high speed, the length of the developer conveyance direction in the developer conveyance supply unit and the developer conveyance unit is increased as described above to sufficiently supply the replenished toner. In order to be charged and supplied to the developer carrying member, it is necessary to lengthen the length of the developer transport supply unit and the developer transport unit very much, and the developing device becomes larger and the image becomes larger. There was a problem that the entire forming apparatus was enlarged.

In addition, when the lengths of the developer transport supply unit and the developer transport unit are extremely increased as described above, the torque applied to the stirring transport member that transports the developer while being mixed and stirred increases, and the stirring transport member is rotated. However, there is a problem that a large amount of power is required and it is difficult to transport the developer while sufficiently mixing and stirring.
JP 2001-109265 A

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems when image formation is performed using a developing device using a developer containing toner and carrier in the image forming device.

  That is, in the present invention, even when the image forming speed in the above-described image forming apparatus is increased, the developer containing the toner and the carrier is sufficiently mixed and stirred in the developing apparatus. Even when a developer containing a large amount of new toner is replenished, the replenished toner is used for development in a properly charged state, causing toner scattering or fogging in the formed image. In addition, the toner density in the developer in the developing device is prevented from being uneven, and density unevenness is prevented from occurring in the formed image. It is an object to be obtained.

In the developing device of the present invention, in order to solve the above-described problems, the developer containing the toner and the carrier is conveyed while being mixed and agitated by the agitating and conveying member provided with the agitating and conveying blades, and the developer is developed. The developer transport supply unit that supplies the carrier and the developer guided to the discharge port on the downstream side in the developer transport direction in the developer transport supply unit are mixed and stirred by the stirring transport member provided with the stirring transport blade. In a developing device provided with a plurality of developer transport sections to be transported while being partitioned by partition walls, the developer is introduced to the next developer transport section downstream in the developer transport direction in each developer transport section And a return port for returning the developer to the upstream side in the developer transport direction in the developer transport supply section. , In at least one of the introduction, the pitch of the stirring transport blade in the stirring conveyance member provided in the developer conveying unit on the upstream side to guide the developer in the introduction above, the downstream developer is guided from the introducing portion the staying means is set larger than the pitch of the stirring transport blade in the stirring conveyance member provided in the developer conveying unit is retained developer is provided, agitating and conveying member in the developer carrying supply unit among all the agitation conveying member The developer transport speed of the agitating and transporting blade is the fastest, and the toner replenishing port for replenishing the toner or the developer containing a large amount of toner is located downstream of the discharge port in the developer transport direction, than introducing part developer is retained by the retention means is in so that provided on the upstream side in the conveying direction of the developer.

  Here, in the developing device of the present invention, when the developer is retained in at least one introduction portion by the retention means, the agitation conveyance provided in the upstream developer conveyance portion that guides the developer to the introduction portion. The pitch of the agitating and conveying blades in the member can be made larger than the pitch of the agitating and conveying blades in the agitating and conveying member provided in the developer conveying portion on the downstream side where the developer is guided from this introduction portion.

  It should be noted that the pitch of the stirring and conveying blades in the stirring and conveying member provided in the upstream developer conveying portion in this way is made larger than the pitch of the stirring and conveying blades in the stirring and conveying member provided in the downstream developer conveying portion. Makes the entire pitch of the stirring and conveying blades in the stirring and conveying member provided in the upstream developer conveying portion larger than the entire pitch of the stirring and conveying blades in the stirring and conveying member provided in the downstream developer conveying portion. In addition, the pitch of the agitating and conveying blades in one agitating and conveying member is changed between the upstream side and the downstream side, and the pitch of the agitating and conveying blades on the downstream side in the agitating and conveying member provided in the upstream developer conveying unit is The pitch of the agitating / conveying blades on the upstream side in the agitating / conveying member provided in the downstream developer conveying portion where the developer is guided from the portion can be made larger.

  In the developing device of the present invention, it is preferable that the developer carrying member is provided so as to be positioned between the discharge port and the return port in the developer transport supply unit.

  Further, the developer replenished with toner or a developer containing a large amount of toner in this manner is sufficiently mixed and stirred in each developer transport section so that the replenished toner is sufficiently charged. In order to return the toner to the developer transport and supply unit, it is preferable to provide a toner replenishment unit that replenishes toner or a developer containing a large amount of toner at a position away from the return port. It is preferable to provide the first developer transport section where the developer is guided from the discharge port of the transport supply section.

  In the image forming apparatus of the present invention, the developing device as described above is used.

  In the developing device of the present invention, the developer guided to the discharge port on the downstream side in the developer transport direction in the developer transport supply section is agitated and transported in a plurality of developer transport sections provided by partitioning the partition walls. And the developer is sequentially guided to the next developer transport section through the introduction section provided on the downstream side in the developer transport direction in each developer transport section. Thus, the developer is further sufficiently mixed in the introduction portion where the developer is retained, and is guided to the next developer conveyance portion, and is guided downstream in the developer conveyance direction in the final developer conveyance portion. The developer is returned to the upstream side in the developer conveyance direction in the developer conveyance supply unit through the return port.

  In the developing device of the present invention, when a new toner or a developer containing a large amount of toner is supplied from the toner replenishing unit, the replenished toner or the developer containing a large amount of toner is changed as described above. While being mixed and agitated by the agitating and conveying member provided in the agent conveying portion, the developer is further conveyed along the developer conveying portions in order, and the developer is further added in the introduction portion where the developer is retained by the retention means. Mix well.

  For this reason, in the developing device of the present invention, newly supplied toner or toner can be obtained without increasing the length of the developer conveying direction in the developer conveying / supplying section or the developer conveying section as in the prior art. A large amount of developer is sufficiently mixed and agitated with the developer in the developing device to be transported, so that the replenished toner can be sufficiently charged and the developing device can be charged without increasing the size of the developing device. In the state where the toner density in the developer is uniformized, the developer is returned to the upstream side in the developer transport direction in the developer transport supply section through the return port.

  In the developing device of the present invention, the toner replenishing unit for replenishing new toner or a developer containing a large amount of toner is disposed on the downstream side in the developer transport direction from the discharge port in the developer transport supply unit. When provided at a position upstream of the introduction direction where the developer is retained by the retention means and away from the return port, the developer to which new toner is replenished is provided. The developer is mixed and agitated in the developer conveying section, and the replenished toner is further sufficiently charged, and the toner concentration in the developer is further uniformed, and the developer is returned to the final developer conveying section. The replenished toner is more fully charged and the developer having a constant toner density is supplied from the developer conveying unit to the developer carrying member. Uninaru.

  Further, in the developing device of the present invention, when the developer carrying member is provided so as to be positioned between the discharge port and the return port in the developer transport supply unit, a stable amount of developer from the developer transport supply unit. Is guided to the developer carrying member, and the amount of the developer supplied to the entire developer carrying member is stabilized.

  In the image forming apparatus using such a developing device, even when the image forming speed is increased, the developer containing the toner and the carrier is sufficiently mixed and stirred in the developing device. Even when new toner is replenished, the replenished toner is sufficiently charged and the developer with a constant toner density is supplied to the developer carrier and used for development, causing toner scattering. In addition, it is possible to appropriately prevent fogging and density unevenness from occurring in an image to be formed, and stable image formation can be performed.

  Next, an image forming apparatus and a developing apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the image forming apparatus and the developing apparatus according to the present invention are not limited to those shown in the following embodiments, and can be appropriately modified and implemented without departing from the scope of the invention.

  In the image forming apparatus according to this embodiment, as shown in FIG. 1, the image carrier 1 made of a photosensitive drum is rotated, and the surface of the image carrier 1 is charged by the charging device 2. The surface of the image carrier 1 is exposed according to image information by a latent image forming apparatus 3 using a laser or the like, and an electrostatic latent image is formed on the surface of the image carrier 1.

  Then, toner is supplied from the developing device 4 to the portion of the electrostatic latent image formed on the surface of the image carrier 1 in this way, and a toner image corresponding to the electrostatic latent image is formed on the surface of the image carrier 1. After that, the recording sheet s is guided by the timing roller 6 between the image carrier 1 on which the toner image is formed and the transfer device 5, and is formed on the surface of the image carrier 1 by the transfer device 5. The toner image is transferred, and the recording medium 6 onto which the toner image has been transferred in this manner is guided between a pair of rollers 7a provided in a heating type fixing device 7, and the toner image is transferred between the pair of rollers 7a. s is fixed by heating.

  On the other hand, the cleaning member 8 is brought into pressure contact with the surface of the image carrier 1 after the toner image is transferred as described above, and the residue such as the toner remaining on the surface of the image carrier 1 after the transfer is removed. Thereafter, the image carrier 1 is charged by the charging device 2 as described above, and the above operation is repeated to continuously perform image formation.

  Here, in the developing device 4 in this embodiment, as shown in FIG. 1, the developer d containing the toner and the carrier is accommodated in the developing device 4 and is rotated as the developer carrying member 41. In the developing roller 41a, a magnet roller 41b provided with a plurality of magnetic poles N, S,... Is fixed and used.

  Then, the developer d is supplied from the developer transport supply unit 42 to the surface of the rotating developing roller 41a, and the amount of the developer d supplied to the surface of the developing roller 41a is regulated by the regulating member 43. Thereafter, the developing roller 41a guides the developer d to the developing area facing the image carrier 1.

  The toner in the developer d thus guided to the development area by the developing roller 41a is supplied to the portion of the electrostatic latent image formed on the surface of the image carrier 1 as described above, and the image carrier After the toner image corresponding to the electrostatic latent image is formed on the surface of the body 1, the developer d on the surface of the developing roller 41 a is applied by the repulsive magnetic force between the N and N poles of the same polarity in the magnet roller 41 b. The developer is separated from the surface of the developing roller 41a and returned to the developer transport supply unit 42 described above.

  Here, in the developing device 4 of this embodiment, as shown in FIG. 1 and FIG. 2, the developer transport supply section 42 and the developer transport supply section 42 on the downstream side in the transport direction of the developer d. The first, second, third, and fourth four developer transport portions 44, 45, 46, and 47 that transport the developer d guided to the discharge port 42a while being mixed and stirred are partitioned by a partition wall 48. In addition, the developer d is conveyed to the developer conveyance supply unit 42 and the first, second, third, and fourth developer conveyance units 44, 45, 46, and 47 with stirring. Agitating and conveying members 52, 54, 55, 56 and 57 having agitating and conveying blades 52a, 54a, 55a, 56a and 57a are provided, and the agitating and conveying members 52, 54, 55, 56 and 57 are rotated by the rotating means 50. I have to.

  Then, the first developer conveying portion 44 to which the developer d is guided through the discharge port 42a of the developer conveying and supplying portion 42 is positioned farthest from the developer conveying and supplying portion 42 and the developer conveying and supplying portion 42. The second developer transport unit 45 disposed in parallel with the developer transport supply unit 42 is connected to the second transport unit 45, and the second, third, and fourth developer transport units 45, 46, and 47 are connected to each other. The second developer transport unit 45 is arranged in parallel so as to approach the developer transport supply unit 42 in order.

  Further, the developer d is transferred to the next developer transport portions 45, 46, 46, respectively, on the downstream side in the transport direction of the developer d in the first, second, and third developer transport portions 44, 45, 46. The first, second, and third introduction portions 49a, 49b, and 49c leading to 47 are provided, and the developer d is developed downstream in the transport direction of the developer d in the final fourth developer transport portion 47. A return port 42b is provided in the developer transport supply section 42 to return to the upstream side in the transport direction of the developer d.

  In the developing device 4, the agitating and conveying member 52 provided in the developer conveying and supplying unit 42 is rotated, and the developer d in the developer conveying and supplying unit 42 is conveyed while being agitated. While the developer d is being supplied to the developing roller 41a, the developer d is transported to the discharge port 42a on the downstream side in the transport direction of the developer d in the developer transport supply unit 42, and the developer d is passed through the discharge port 42a. 1 to the developer conveying section 44 of one developer.

  Further, the first to fourth four developer transport portions 44 to 47 are rotated by rotating the respective stir transport members 54 to 57 provided in the first to fourth four developer transport portions 44 to 47. The developer d is conveyed while being mixed and stirred, and the developer d guided to the first developer conveying portion 44 through the discharge port 42a as described above is supplied to each of the first to third introduction portions. 49a, 49b, and 49c are sequentially led to the second to fourth developer transport units 45 to 47, and through the return port 42b provided on the downstream side in the transport direction of the developer d in the fourth developer transport unit 47. The developer d is returned to the upstream side in the transport direction of the developer d in the developer transport supply unit 42.

  In this way, the developer d guided to the discharge port 42a of the developer transport supply unit 42 is mixed with the stirring transport members 54 to 57 in the first to fourth developer transport units 44 to 47 described above. Thus, the developer d sufficiently mixed and stirred is returned to the developer transport supply section 42 through the return port 42b and used for development.

  Here, in the developing device 4, the agitating and conveying members 55, 56 and 57 provided in the second, third and fourth developer conveying portions 45, 46 and 47 are rotated by the rotating means 50. Thus, when the developer d is transported while being mixed and stirred in the second to fourth developer transport portions 45 to 47, the stirring transport members 55 and 57 in the second and fourth developer transport portions 45 and 47 are transported. Is rotated in the opposite direction to the agitating / conveying member 52 in the developer conveying / supplying section 42, and the developer d in the second and fourth developer conveying sections 45 and 47 is rotated in the opposite direction to the developer conveying / supplying section 42 described above. On the other hand, the agitating and conveying member 56 in the third developer conveying unit 46 is rotated in the same direction as the agitating and conveying member 52 in the developer conveying and supplying unit 42, and the developer d in the third developer conveying unit 46 is transferred. Developer transport supply unit 42 And so as to be conveyed in the same direction.

  Further, in the developing device 4 of this embodiment, since the developer d is retained in the first to third introduction portions 49a to 49c by the retention means, the first to fourth components described above are used. The pitch of the stirring and conveying blades 54a to 57a in each of the stirring and conveying members 54 to 57 provided in the developer conveying units 44 to 47 is changed, and the pitch of the entire stirring and conveying blades 54a to 57a in each of the stirring and conveying members 54 to 57 is changed. From the first developer transport section 44 on the upstream side in the transport direction of the developer d to the second developer transport section 45, the third developer transport section 46, and the fourth developer transport on the downstream side in the transport direction of the developer d. It is made to decrease in the order of the part 47. FIG.

  If it does in this way, the conveyance speed of the developer d in the 1st-4th developer conveyance parts 44-47 will become slow sequentially from the 1st developer conveyance part 44 of the conveyance direction upstream of the developer d. The developer d accumulates in the first to third introduction portions 49a to 49c provided on the downstream side in the conveyance direction of the developer d in the first to third developer conveyance portions 44 to 46. The developer d is sufficiently mixed in the portions 49a to 49c.

  Further, in the developing device 4, as shown in FIGS. 1 and 2, when the toner is replenished from the toner replenishing device 60 into the developing device 4, the developer d is discharged from the discharge port 42 a of the developer transport supply unit 42. In the guided first developer transport section 44, a toner replenishing port 61 is provided upstream in the transport direction of the developer d from the first introduction section 49a that guides the developer d to the second developer transport section 45. The toner is supplied from the toner supply device 60 through the toner supply port 61.

  As described above, when toner is replenished from the toner replenishment port 61 on the upstream side of the first introduction portion 49a in the transport direction of the developer d, the replenished toner is first discharged from the discharge port 42a of the developer transport supply unit 42. Agitated and mixed by the agitating / conveying members 55 to 57 provided in the first to fourth developer conveying portions 44 to 47 together with the developer d guided to the developer conveying portion 44. While being conveyed, the replenished toner is sufficiently charged with sufficient contact with the carrier in the developer d, and the toner is replenished in each of the first to third introduction portions 49a to 49c. Developer d stays and developer d replenished with toner is sufficiently mixed with other developer d, so that the toner concentration in developer d is made uniform.

  Then, the toner replenished in this manner is sufficiently charged and the developer d is supplied to the developer transport / supply section 42 through the return port 42b in a state where the toner density in the developer d is uniformized. Be guided.

  For this reason, in the image forming apparatus using the developing device 4 as described above, even when the image forming speed is increased, the supplied toner is sufficiently charged and the toner concentration in the developer d is constant. In this state, the developer d is supplied to the developing roller 41a and used for development, and it is possible to appropriately prevent occurrence of toner scattering and occurrence of fog and density unevenness in the formed image. Can be performed stably.

  In the developing device 4, the developer carrier 41 is positioned between the discharge port 42 a and the return port 42 b in the developer transport supply unit 42. When the developer carrier 41 is positioned between the discharge port 42a and the return port 42b in the developer transport supply unit 42, a constant amount of developer d is stabilized from the developer transport supply unit 42 to the entire developing roller 41a. Thus, the occurrence of uneven density is further suppressed.

  In the developing device 4 described above, only the toner is replenished from the toner replenishing device 60, but it is also possible to replenish the developer d containing a large amount of toner. In this case, since the amount of the carrier in the developer d gradually increases, it is necessary to provide a collection unit (not shown) for collecting a part of the developer d. In order to prevent the developer d contained therein from being immediately collected by the collection unit, the collection unit is located downstream of the discharge port 42b in the transport direction of the developer d and contains a large amount of toner. Is preferably provided at a position upstream of the developer replenishment direction with respect to the developer d.

Further, in the developing device 4 of this embodiment, the first to fourth developer transport portions 44 described above are used as retention means for retaining the developer d in the first to third introduction portions 49a to 49c. The pitches of the agitating / conveying blades 54a to 57a in the agitating / conveying members 54 to 57 provided in the .about.47 are set downstream of the developer d in the conveying direction of the developer d from the first developer conveying portion 44 upstream in the conveying direction of the developer d. The second developer transport unit 45, the third developer transport unit 46, and the fourth developer transport unit 47 are decreased in this order, but the developer d is retained in each of the introduction units 49a to 49c. Therefore, it is also possible to add the following staying means.

  For example, as shown in FIG. 3, the pitch of the agitating and conveying blades 54 a to 57 a in the agitating and conveying members 55 to 57 provided in the second to fourth developer conveying units 45 to 47 is set upstream of the developer d in the conveying direction. And the developer d in the transport direction downstream side, the pitch on the upstream side in the transport direction of the developer d is made smaller than the pitch on the downstream side in the transport direction of the developer d, and the second to fourth developments In the developer transport sections 45 to 47, the developer d is transported at the upstream side in the transport direction of the developer d, and the developer d is retained in the first to third introduction sections 49a to 49c. Can be.

  Moreover, as shown in FIG. 4, without changing the pitch of each stirring conveyance blade | wing 54a-57a in each stirring conveyance member 54-57 provided in said 1st-4th developer conveyance part 44-47, The speed at which the agitating and conveying members 54 to 57 are rotated by the rotating means 50 is changed, and the rotating speed of the agitating and conveying members 52, 54, 55, 56, and 57 is changed to the first speed upstream of the developer d in the conveying direction. The developer d can be retained in each of the first to third introduction portions 49a to 49c by sequentially delaying from the stirring and conveying member 54 in the one developer conveying portion 44.

  Further, as shown in FIG. 5, the widths in the first to fourth developer transport sections 44 to 47 are changed, and the first developer transport section 44 on the upstream side in the transport direction of the developer d is changed from the first developer transport section 44 to the first developer transport section 44. The widths of the second developer transport unit 45, the third developer transport unit 46, and the fourth developer transport unit 47 are narrowed in this order, and development is performed in each of the first to third introduction units 49a to 49c. The agent d can be retained.

  Further, as shown in FIG. 6, the sizes of the first to third introduction portions 49a to 49c are changed, and the second introduction is performed from the first introduction portion 49a on the upstream side in the transport direction of the developer d. It is possible to make the developer d stay in the second and third introduction portions 49b and 49c by decreasing the size in the order of the portion 49b and the third introduction portion 49ca.

  In the developing device 4 of this embodiment, the developer d is retained in the first to third introduction portions 49a to 49c, but the first to third introduction portions 49a to 49c are used. The developer d may be retained only in any one of the above.

  Further, in the developing device 4 of this embodiment, the first to fourth developer conveying units 44 to 47 that convey the developer d guided through the discharge port 42b of the developer conveying and supplying unit 42 while stirring. However, the number of developer conveying units is not limited to four, and the developer is supplied to the developer in the developer conveying and supplying unit through the return port from the downstream side in the developer conveying direction in the final developer conveying unit. It is possible to provide more developer conveying sections as long as the developer is returned to the upstream side in the conveying direction.

  Further, in the developing device 4 described above, the developer d is guided to the developing region facing the image carrier 1 by the developing roller 41a as described above, and the portion of the electrostatic latent image formed on the surface of the image carrier 1 In this case, the toner in developer d is supplied to develop the electrostatic latent image formed on the surface of image carrier 1, but only the toner in developer d held by developer roller 41a is used. Is held on a toner holding member (not shown), and toner is supplied from the toner holding member to a portion of the electrostatic latent image formed on the surface of the image carrier 1, so that the toner is formed on the surface of the image carrier 1. It is also possible to develop the electrostatic latent image. Further, although not shown, it is also possible to conduct development by guiding the developer to a developing area facing the image carrier with two or more developing rollers.

  Further, the developer d including the toner and the carrier used in the developing device 4 is not particularly limited, and a commonly used known developer can be used.

  Here, as the toner, a colorant in the binder resin, and if necessary, a charge control agent, a release agent, etc., which are treated with external additives can be used. Although not particularly limited, those of about 3 to 15 μm are desirable.

  And in manufacturing such a toner, it can manufacture by the well-known method generally used, for example, it can manufacture using a pulverization method, an emulsion polymerization method, a suspension polymerization method etc.

  In addition, as the binder resin used for the toner, a publicly known resin can be used. For example, a styrene resin (monopolymer or copolymer containing styrene or a styrene substitution product), a polyester resin, Epoxy resins, vinyl chloride resins, phenol resins, polyethylene resins, polypropylene resins, polyurethane resins, silicone resins, and the like can be used, but are not limited to these. These resins can be used as a single substance or a composite, and those having a softening temperature in the range of 80 to 160 ° C. and those having a glass transition point in the range of 50 to 75 ° C. are preferably used.

  Further, as the above-mentioned colorant, publicly known publicly known ones can be used. For example, carbon black, aniline black, activated carbon, magnetite, benzine yellow, permanent yellow, naphthol yellow, phthalocyanine blue, first sky blue Ultramarine Blue, Rose Bengal, Lakey Red, etc. can be used, and it is generally preferable to use 2-20 parts by weight with respect to 100 parts by weight of the binder resin.

  Also, known charge control agents can be used. Examples of charge control materials for positively chargeable toners include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds, Imidazole compounds, polyamine resins, etc. can be used, and charge control materials for negatively chargeable toners include metal-containing azo dyes such as Cr, Co, Al, Fe, salicylic acid metal compounds, alkyl salicylic acid metal compounds, Lixarene compounds can be used. In general, such a charge control agent is preferably used at a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  In addition, as the above-mentioned mold release agent, known ones that are generally used can be used. For example, polyethylene, polypropylene, carnauba wax, sazol wax and the like can be used alone or in combination of two or more. In general, it is preferably used at a ratio of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  Further, as the particles externally added to the toner, commonly used known particles can be used, and for example, silica, titanium oxide, aluminum oxide or the like is used as a fluidizing agent for improving the fluidity of the toner. In particular, it is preferable to use a silane coupling agent, a titanium coupling agent, a silicone oil or the like made water repellent. Such a fluidizing agent is added at a ratio of 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner. The number average primary particle size of the fluidizing agent is preferably 10 to 100 nm.

  Further, as the carrier, a known carrier that is generally used can be used, and a binder-type carrier, a coat-type carrier, or the like can be used. The particle size of this carrier is not particularly limited, but is 15 to 100 μm. Is preferred.

  Here, the binder type carrier is one in which magnetic fine particles are dispersed in a binder resin, and positive or negative chargeable fine particles are fixed to the carrier surface or a surface coating layer is provided. You can also. Further, the charging characteristics such as the charging polarity of the binder type carrier can be controlled by the type of the binder resin material, the chargeable fine particles, and the surface coating layer.

  And as binder resin used for this binder type carrier, thermoplastic resin, such as vinyl resin represented by polystyrene resin, polyester resin, nylon resin, polyolefin resin, thermosetting properties, such as phenol resin, for example Resin can be used.

  Magnetic fine particles used for the binder type carrier include spinel ferrite such as magnetite and gamma iron oxide, spinel ferrite containing one or more metals other than iron (Mn, Ni, Mg, Cu, etc.), and barium ferrite. Magneto-plumbite type ferrite such as iron, iron or alloy particles having iron oxide on the surface can be used, and the shape thereof may be any of granular, spherical and acicular.

  In particular, when high magnetization is required for the binder type carrier, it is preferable to use iron-based ferromagnetic fine particles. In consideration of the chemical stability of the binder type carrier, it is preferable to use ferromagnetic fine particles of magnetoplumbite type ferrite such as spinel ferrite and barium ferrite containing magnetite and gamma iron oxide. And the binder type | mold carrier which has desired magnetization can be obtained by selecting the kind and content of a ferromagnetic fine particle suitably. The magnetic fine particles are suitably added in an amount of 50 to 90% by weight in the binder type carrier.

  Moreover, as a material of said surface coating layer in a binder type | mold carrier, a silicone resin, an acrylic resin, an epoxy resin, a fluorine resin etc. are used, for example, these resin is coated on the surface, and it hardens | cures and forms a coating layer By doing so, the charge imparting ability can be improved.

  Further, in fixing the chargeable fine particles or the conductive fine particles to the surface of the binder type carrier, for example, after the binder type carrier and these fine particles are uniformly mixed and adhered to the surface of the binder type carrier. By applying mechanical and thermal impact force, these fine particles can be fixed by being driven into a binder type carrier. In this case, these fine particles are not completely embedded in the binder type carrier, but are fixed so as to protrude from the surface of the binder type carrier.

  Here, as the chargeable fine particles, organic or inorganic insulating materials can be used. Specifically, organic insulating materials such as polystyrene, styrene copolymers, acrylic resins, various acrylic copolymers, nylon, polyethylene, polypropylene, fluororesins, and cross-linked products thereof, for example. Fine particles can be used. Regarding the charge level and polarity, a desired level of charge and polarity can be obtained by a material, a polymerization catalyst, a surface treatment, and the like. As the inorganic insulating material, for example, negatively charged inorganic fine particles such as silica and titanium dioxide, and positively charged inorganic fine particles such as strontium titanate and alumina can be used.

  In addition, the above-mentioned coated carrier is a carrier in which a resin coat layer is provided on the surface of carrier core particles made of a magnetic material. In this coated carrier, as in the binder-type carrier, Alternatively, negatively chargeable fine particles can be fixed.

  The charging characteristics such as polarity of the coat type carrier can be controlled by the type of the resin coat layer and the chargeable fine particles, and the same material as the binder type carrier can be used. In particular, a resin similar to the binder resin of the binder type carrier can be used for the resin of the resin coat layer.

  The mixing ratio of the toner and the carrier may be adjusted so as to obtain a desired toner charge amount, and the ratio of the toner to the total amount of the toner and the carrier is 3 to 50% by weight, preferably 6 to 6%. 30% by weight is suitable.

1 is a schematic explanatory diagram illustrating a state in which image formation is performed in an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view showing the inside of a developing device used in the image forming apparatus according to the embodiment. In the developing device used in the image forming apparatus according to the above-described embodiment, a schematic diagram showing a first modification in which the staying means for retaining the developer is changed in the introduction portion that guides the developer to the next developer transporting portion. It is explanatory drawing. In the developing device used in the image forming apparatus according to the above-described embodiment, a schematic explanatory diagram showing a first additional example in a staying means for staying the developer in an introduction portion that guides the developer to the next developer transporting portion. is there. In the developing device used in the image forming apparatus according to the above-described embodiment, a schematic explanatory diagram showing a second additional example in the staying means for staying the developer in the introduction portion that guides the developer to the next developer transporting portion. is there. In the developing device used in the image forming apparatus according to the above-described embodiment, a schematic explanatory diagram showing a third additional example in the staying means for retaining the developer in the introduction portion that guides the developer to the next developer transporting portion. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Charging device 3 Latent image forming device 4 Developing device 5 Transfer device 6 Timing roller 7 Fixing device 7a Roller 8 Cleaning member 41 Developer carrying member 41a Developing roller 41b Magnet roller 42 Developer transport supply unit 42a Discharge port 42b Return port 43 Restriction member 44, 45, 46, 47 Developer conveying part 48 Partition 49a, 49b, 49c Introducing part 50 Rotating means 60 Toner replenishing device 61 Toner replenishing port 52, 54, 55, 56, 57 Stirring conveying member 52a, 54a, 55a, 56a, 57a Stirring conveying blade d Developer s Recording sheet

Claims (6)

A developer conveying and supplying unit that conveys the developer including toner and carrier while being mixed and agitated by an agitating and conveying member provided with an agitating and conveying blade, and that supplies the developer to the developer carrying member, and the developer conveying and supplying unit And a plurality of developer transport portions that are transported while being mixed and stirred by the stirring transport member provided with the stirring transport blades. In the developed developing device, an introduction portion that guides the developer to the next developer transport portion is provided downstream of the developer transport portion in each developer transport portion, and downstream of the developer transport direction in the final developer transport portion. the developer on the side of the return port is provided back to the upstream side of the developer in the developer conveying supply unit, at least one inlet section, a developer in the introductory part of the electrically The pitch of the agitating and conveying blades in the agitating / conveying member provided in the upstream developer conveying unit is greater than the pitch of the agitating and conveying blades in the agitating and conveying member provided in the downstream developer conveying unit from which the developer is guided from this introduction unit. A stagnant means for retaining the developer is provided , and among all the agitating and conveying members, the developer conveying speed by the agitating and conveying blades of the agitating and conveying member in the developer conveying and supplying section is the fastest, and the toner or The toner replenishing port for replenishing the developer containing a large amount of toner is located downstream of the discharge port in the developer transport direction, and more than the introduction portion where the developer is retained by the retention means. A developing device provided on the upstream side in the transport direction . 2. The developing device according to claim 1, wherein a pitch of the agitation conveyance blades in the agitation conveyance members provided in the plurality of developer conveyance units is provided in the developer conveyance unit adjacent to the downstream side of the discharge port. A developing device characterized in that the pitch of the agitating and conveying blades of the agitating and conveying member is the largest, and is set so as to gradually decrease toward the downstream side . The developing device according to claim 1 or claim 2, as the residence means, the overall pitch of the stirring transport blade in the stirring conveyance member provided in the developer conveying unit on the upstream side to guide the developer in the introductory part of the The developing device is characterized in that is made larger than the entire pitch of the agitating and conveying blades in the agitating and conveying member provided in the developer conveying portion on the downstream side from which the developer is guided from the introduction portion. The developing device according to claim 1 or claim 2, as the residence means, stirring transport blade on the downstream side of the agitating and conveying member provided in the developer conveying unit on the upstream side to guide the developer in the introductory part of the A developing device characterized in that the pitch is made larger than the pitch of the agitating / conveying blades on the upstream side in the agitating / conveying member provided in the developer conveying unit on the downstream side from which the developer is guided from this introduction part. 5. The developing device according to claim 1, wherein the developer carrying member is provided so as to be positioned between a discharge port and a return port in the developer transport supply unit. A developing device. 6. An image forming apparatus using the developing device according to claim 1, further comprising a toner replenishing device that replenishes toner or a developer containing a large amount of toner.

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