JP2010217799A - Developing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fully mix a developing agent containing toner and carrier without using a larger developing device and to use the supplied and appropriately charged toner for development. <P>SOLUTION: In the developing device 20, the developing agent D containing the toner and the carrier guided out of a guide port 25a provided downstream in the conveyance direction of a developing agent conveyance supply part 22 which stirs, conveys and supplies the developing agent D to a developing agent carrier 21 is sequentially guided to a plurality of developing agent conveyance parts 26a-26c through each guide port 25b, 25c for stirring and conveying and is returned upstream in the conveyance direction of the developing agent at the developing agent conveyance supply part from the guide port 25d of the last developing agent conveyance part 26c. The developing device 20 has a portion where the developing agent is guided through the guide port by the force of gravity and a portion where the developing agent is guided through the guide port against the force of gravity, and the length of at least some of the developing agent conveyance parts other than the last developing agent conveyance part is reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

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, in an image forming apparatus using a developing device using a developer containing a toner and a carrier, even when the image forming speed is increased, the developer is sufficiently mixed and stirred without increasing the size of the developing device. Thus, when new toner is replenished, the replenished toner is appropriately charged and used for development.

  Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a composite machine of these, an image is carried by supplying toner from a developing device to an electrostatic latent image formed on an image carrier such as a photoconductor. 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 agitated by a stirring and conveying member in a developer conveying portion in the developing device. The toner is brought into contact with the carrier and charged, and the developer charged with the toner in this way is guided to a developer conveying and supplying unit that supplies the developer carrying member.

  In the developer transport and supply section, the developer is supplied to the developer carrier, and toner is supplied from the developer carrier to the electrostatic latent image formed on the image carrier to perform development. The developer is transported while being stirred by the stirring transport member, and the developer is circulated between the developer transport section and the developer transport supply section.

  In addition, 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 toner concentration in the developer gradually decreases, resulting in an image being formed. Therefore, when the toner concentration in the developer decreases to some extent, new toner is supplied to the developer.

  Here, the newly replenished toner is in an uncharged state, and the developer is guided to the developer transport supply unit in a state where the replenished toner is not sufficiently charged, and this developer transport supply unit When the toner is supplied to the developer carrying member and used for development, there are problems such as toner scattering and fogging in the formed image.

  For this reason, conventionally, as disclosed in Patent Document 1, a developer transport supply unit that supplies the developer to the developer carrying member while stirring and transporting the developer by the stirring and transporting member, and a developer transporting and stirring member The length of the developer conveying direction in the developer conveying section that circulates the developer between the developer conveying supply section and the developer conveying supply section is increased, and the distance to convey the developer while mixing and agitating is increased. It has been proposed to lengthen and charge the replenished toner sufficiently.

  However, when the length of the developer conveyance direction in the developer conveyance supply unit and the developer conveyance unit is increased in this way, in particular, as in recent years, the image formation speed in the image forming apparatus is increased to increase the image speed. In forming the toner, in order to sufficiently charge the replenished toner and supply it to the developer carrier, it is necessary to make these lengths very long. There is a problem that the entire image forming apparatus becomes very large due to the extremely long length. In addition, when the lengths of the developer transport supply unit and the developer transport unit are very long as described above, the torque applied to the stirring transport member that transports the developer while stirring the developer 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 stirring it.

  Conventionally, as disclosed in Patent Document 2, a first agitation member is provided in the developer conveyance supply unit, and two second agitation members and a third agitation member are provided in parallel in the developer conveyance unit. The developer transport direction in the first stirring member and the second stirring member is the same direction, while the developer transport direction in the third stirring member is reversed, and the developer transport amount by the second stirring member is There has been proposed one in which the amount of developer transported by the three stirring members is controlled.

  However, in the one disclosed in Patent Document 2, it can not be said that the newly supplied toner is sufficiently mixed and stirred in the developer and guided to the developer transport and supply unit. When used for development in a state where it is not sufficiently charged, there still existed problems such as toner scattering and fogging in the formed image. Further, as described above, when the two second agitating members and the third agitating member are provided in parallel in the developer conveying portion, the width of the developer conveying portion in the direction in which the two agitating members are arranged in parallel is large. For example, the position where a latent image forming apparatus that forms an electrostatic latent image by irradiating light to an image carrier is limited, and there is a problem that the types of image forming apparatuses that can be used are limited. .

JP 2001-109275 A JP 2006-47456 A

  An object of the present invention is to solve the above-described problems in an image forming apparatus that forms an image using a developing device using a developer containing a toner and a carrier.

  That is, in the present invention, even when the image forming speed in the image forming apparatus as described above is increased, the developer containing the toner and the carrier is sufficiently mixed and stirred in the developing apparatus to supply new toner. Even in this case, the replenished toner is appropriately charged and used for development, so that toner scattering does not occur and fog does not occur in the formed image, and the developing device is enlarged, This is characterized in that the image forming apparatus is not enlarged and the developing device does not interfere with image formation.

  In the developing device of the present invention, in order to solve the above-described problems, a developer conveying and supplying unit that agitates and conveys the developer including the toner and the carrier and supplies the developer to the developer carrying member, and the development. And a plurality of developer conveying units that sequentially stir and convey the developer led out through the outlet port on the downstream side in the developer conveying direction in the developer conveying and supplying unit, and each developer conveying unit downstream in the developer conveying direction A lead-out port for introducing the developer to the next developer transport section is provided on the side, and the developer is transported in the developer transport supply section on the downstream side in the developer transport direction in the final developer transport section. A lead-out port that returns to the upstream side is provided. In the developer transport supply unit and each developer transport unit, a portion where the developer is led out through the lead-out port by gravity, and the developer passes through the lead-out port against gravity. Derived To have a minute and the length of the final developer least a portion of the developer conveying unit other than the transport unit has been shortened.

  Further, in the developing device of the present invention, the lengths of all the developer conveying units other than the final developer conveying unit described above are shortened, and the developer conveying unit thus shortened has a developing function. It is desirable not to exist in a part where the developer is supplied to the developer carrying member in the agent transport supply unit.

  In the developing device of the present invention, the developer in the developer transport / supply section is directly supplied to the developer carrier, and a supply member is provided between the developer transport / supply section and the developer carrier. The developer in the developer transport supply unit can be supplied to the developer carrier via this supply member, and the developer can be supplied to two or more developer carriers via this supply member. It can also be done.

  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 led out through the outlet on the downstream side in the developer transport direction in the developer transport supply unit is sequentially guided to each of the plurality of developer transport units through each outlet, The developer is agitated and conveyed in the developer conveying unit, and the developer thus agitated and conveyed in each developer conveying unit is supplied and conveyed through the outlet in the downstream of the developer conveying direction in the final developer conveying unit. The developer is returned to the upstream side in the conveyance direction of the developer.

  In the developing device of the present invention, as described above, the developer led out through the outlet port on the downstream side in the developer transport direction in the developer transport supply unit is the developer transport direction in the final developer transport unit. While the developer is returned to the upstream side in the developer conveyance direction in the developer conveyance supply section through the downstream outlet, the portion where the developer is led out through the outlet by gravity and the developer through the outlet against gravity Since the portion to be led out is provided, the developer stays in the portion where the developer is led through the lead-out port against gravity, and the time for the developer to be stirred becomes long.

  For this reason, in the developing device of the present invention, even if the length of at least a part of the developer transport section other than the final developer transport section is shortened as described above, it is led out through the outlet of the developer transport supply section. The developed developer is sufficiently mixed and agitated in the plurality of developer conveying units and returned to the developer conveying and supplying unit. Even when new toner is replenished, the replenished toner is appropriately supplied. It is charged and used for development.

  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 appropriately charged and used for development, and it is possible to prevent toner scattering and fogging of the formed image.

  Further, in the developing device of the present invention, as described above, the lengths of all the developer transport units other than the final developer transport unit are shortened, and the developer transport unit whose length is shortened in this way, If the developer conveying / supplying portion does not exist in the portion where the developer is supplied to the developer carrier, the developing device is not reduced in size and the image forming device is not increased in size. The developing device can be used in various existing image forming apparatuses without limiting the position where a latent image forming apparatus or the like for forming an electrostatic latent image by irradiating the carrier with light is limited. Thus, the versatility of the developing device is improved.

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 longitudinal sectional view illustrating a first developing device used in the image forming apparatus according to the embodiment. FIG. 6 is a cross-sectional explanatory view showing a relationship between a developer transport supply unit and a third (final) developer transport unit in the first developing device. FIG. 5 is a schematic explanatory diagram showing the order in which the developer is transported in the developer transport supply unit and the first to third developer transport units in the first developing device. FIG. 3 is a longitudinal cross-sectional explanatory view showing a relationship between a developer transport supply unit and a first developer transport unit in the first developing device. FIG. 4 is a cross-sectional explanatory view showing a relationship between a first developer transport unit and a second developer transport unit in the first developing device. FIG. 5 is a longitudinal cross-sectional explanatory view showing a relationship between a second developer transport unit and a third developer transport unit in the first developing device. The longitudinal sectional view showing the second developing device used in the image forming apparatus according to the above-described embodiment and the developer are conveyed in the developer conveying and supplying unit and the first to third developer conveying units. FIG. The longitudinal sectional view showing the third developing device used in the image forming apparatus according to the above-described embodiment and the developer are conveyed in the developer conveying and supplying unit and the first to third developer conveying units. FIG. In the developing device used in the image forming apparatus according to the above-described embodiment, the developer in the developer transport supply unit is schematically illustrated in a modified example in which the developer is supplied to the surface of the developing roller via the supply roller.

  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, four developing devices are provided corresponding to four photosensitive drums (image carriers) 10 and containing a developer containing toner and carrier. 20 is provided.

  In each developing device 20, a developing roller (developer carrying member) 21 that conveys the developer to the photosensitive drum 10 is provided so as to face the corresponding photosensitive drum 10, and in each developing device 20. Uses different colors of toner in the developer, and uses black, yellow, magenta, and cyan toners.

  Then, when full-color image formation is performed by this image forming apparatus, each of the photosensitive drums 10 is rotated, and the surface of each of the photosensitive drums 10 is charged by the charging device 11, respectively. Each of the photosensitive drums 10 is exposed according to the image formation information by the latent image forming device 12 so that an electrostatic latent image is formed on the surface of each of the photosensitive drums 10.

  Next, with respect to each photosensitive drum 10 on which the electrostatic latent image is formed in this way, the developer is guided to a position facing the photosensitive drum 10 by the developing roller 21 in the corresponding developing device 20, and a predetermined color is obtained. The toner is supplied to the electrostatic latent image on each photoconductive drum 10 for development, and a toner image of each color is formed on the surface of each photoconductive drum 10.

  Then, the toner images of the respective colors formed on the respective photosensitive drums 10 in this manner are respectively transferred to the intermediate transfer body 13 in the form of an endless belt that is driven across the roller 13a. A primary image is sequentially transferred by the transfer device 14 to form a full-color toner image on the intermediate transfer member 13. On the other hand, residues such as toner remaining on the surface of each photoreceptor drum 10 without being transferred to the intermediate transfer body 13 are removed by the first cleaning device 15.

  Next, the full-color toner image formed on the intermediate transfer member 13 as described above is guided to a position facing the secondary transfer device 16 formed into a roller shape by the intermediate transfer member 13 and the image forming apparatus. The recording sheet S accommodated in the lower part of the sheet is guided between the intermediate transfer member 13 and the secondary transfer device 16, and the full-color toner image formed on the intermediate transfer member 13 by the secondary transfer device 16 is transferred to the recording sheet S. Secondary transfer is performed on the recording sheet S.

  Thereafter, the recording sheet S to which the full-color toner image is transferred is guided to the fixing device 17, and the transferred full-color toner image is fixed to the recording sheet S, and then the recording in which the full-color toner image is fixed as described above. The sheet S is discharged. On the other hand, toner and other residues that are not transferred to the recording sheet S and remain on the intermediate transfer member 13 are removed from the intermediate transfer member 13 by the second cleaning device 18.

  Here, in the developing device 20 in this embodiment, as shown in FIGS. 2 and 3, a plurality of magnetic poles N, S, and N are provided inside the developing roller 21 that conveys the developer D to the photosensitive drum 10. Is provided in a fixed manner, and the developer transport supply section 22 facing the developing roller 21 extends to the downstream side of the developing roller 21 in the transport direction of the developer D. The first agitating and conveying member 23a provided in the agent conveying and supplying unit 22 is rotated to convey the developer D while being stirred along the developer conveying and supplying unit 22, and a part of the developer D Is supplied to the surface of the rotating developing roller 21.

  Then, after the amount of the developer D supplied to the surface of the developing roller 21 is regulated by the regulating member 24, the developer D is guided to the developing region facing the photosensitive drum 10 by the developing roller 21, and Thus, the toner in the developer D is supplied to the portion of the electrostatic latent image formed on the surface of the photosensitive drum 10 to form a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 10. Thereafter, the developer D on the surface of the developing roller 21 is separated from the surface of the developing roller 21 by the repulsive magnetic force between the S and S poles of the same polarity in the magnet roller 21a, and the developer transport and supply unit described above is used. Return to 22.

  Further, in the developing device 20, the first outlet 25a is provided on the bottom surface of the developer transport and supply section 22 on the downstream side in the transport direction of the developer D, and the first outlet 25a is led out through the first outlet 25a. The developer D is sequentially guided to the first to third developer transport sections 26a to 26c so as to be stirred and transported.

  Here, in the developing device 20 of this embodiment, the first developer conveying portion 26a is provided below the developer conveying and supplying portion 22 extended from the developing roller 21, and the first developing is performed. The second developer transport section 26b having the same length as the developer transport section 26a is juxtaposed along the first developer transport section 26a via the partition wall 27a, and further this second developer. On the transport unit 26b, a third developer transport unit 26c having the same length as the developer transport supply unit 22 is juxtaposed along the developer transport supply unit 22 via the partition wall 27b. ing.

  In the developing device 20, the developer D introduced to the first outlet 25a in the developer transport and supply section 22 is transferred to the first outlet 25a as shown in FIGS. Is guided by gravity to a first developer transport section 26a provided under the developer transport supply section 22, and the developer is transported by the second agitation transport member 23b provided in the first developer transport section 26a. D is conveyed while being agitated, and is supplied to a second outlet 25b provided in the partition wall 27a between the first developer conveying section 26a and the second developer conveying section 26b on the downstream side in the conveying direction of the first developer conveying section 26a. I try to guide you.

  Next, as shown in FIGS. 4 and 6, the developer D introduced to the second outlet 25b in the first developer transport section 26a passes through the second outlet 25b and the second development described above. The developer D is guided to the developer transport section 26b and transported while being stirred by the third stirring transport member 23c provided in the second developer transport section 26b, and the second developer transport section 26b. On the downstream side in the transport direction, the light is guided to a third outlet 25c provided on the upper surface thereof.

  Then, as shown in FIGS. 4 and 7, the developer D guided to the third outlet 25c in the second developer transport section 26b passes through the third outlet 25c against the gravity. The third developer transport section 26c is guided to the third developer transport section 26c, and the fourth developer transport section 23d provided in the third developer transport section 26c transports the developer D while stirring the third developer. On the downstream side in the transport direction of the agent transport section 26c, the developer transport section 26c is guided to a fourth outlet 25d provided in the partition wall 27b between the developer transport and supply section 22.

  Next, as shown in FIGS. 3 and 4, the developer D transported in the final third developer transport section 26 c and guided to the fourth outlet 25 d is transferred to the fourth outlet as shown in FIGS. 3 and 4. The developer transport supply unit 22 returns to the upstream position in the transport direction of the developer D through 25d.

  When the toner density in the developer D decreases as a result of development in the developing device 20, the developer transport direction in which the developer D is transported from the developing roller 21 in the developer transport and supply unit 22. The toner is replenished from a toner replenishing port 28 provided in a portion extending downstream.

  As described above, when the toner is supplied to the portion extending from the developing roller 21 to the downstream side in the transport direction of the developer D, the developer D to which the toner is supplied becomes the first to third three as described above. The developer is transported while being agitated in the developer transport units 26a to 26c, and in particular, the developer D from the third outlet 25c in the second developer transport unit 26b is resisted by gravity to the third developer transport unit 26c. In the leading portion, the developer D stays and is sufficiently stirred, and the replenished toner is appropriately charged, and the developer D is positioned upstream in the transport direction of the developer D in the developer transport supply unit 22. Returned to be used for development.

  As a result, in the image forming apparatus using the developing device 20, even when the image forming speed is increased, the developer D including the toner and the carrier is sufficiently mixed and stirred, and new toner is supplied. However, the replenished toner is appropriately charged and used for development, and toner scattering and fogging are prevented from occurring in the formed image.

  Further, in the developing device 20 described above, the first and second developer transport sections 26a and 26b are made shorter than the developer transport supply section 22 and the third developer transport section 26c, as described above. Since the developer conveying supply unit 22 does not exist at the position where the developer D is supplied to the developing roller 21, the developing device 20 is not downsized and the image forming apparatus is not enlarged, and as described above. When the latent image forming device 12 exposes the photosensitive drum 10 to form an electrostatic latent image, the developing device 20 does not get in the way.

  In this embodiment, the developing device 20 is provided with the first to third developer transport portions 26a to 26c. However, it is possible to provide more developer transport portions.

  Also, the positions at which the first to third developer conveying portions 26a to 26c are provided are not particularly limited to those shown in the above embodiment.

  For example, as in the developing device 20 of the second embodiment shown in FIGS. 8A and 8B, the first developer conveying portion 26 a extends from the developing roller 21 and the developer conveying and supplying portion 22 extends. A second developer conveying portion 26b which is provided below and has the same length as the first developer conveying portion 26a is arranged in parallel along the first developer conveying portion 26a via a partition wall 27a. In addition, below this second developer transport section 26b, a third developer transport section 26c having the same length as the developer transport supply section 22 is transported through the partition wall 27b. It is also possible to arrange them side by side along the supply unit 22.

  In the developing device 20 according to the second embodiment, as shown in FIG. 8B, the developer D guided to the downstream side in the transport direction of the developer D in the developer transport supply unit 22 is brought to gravity. On the contrary, the developer D is supplied to the first developer conveying portion 26a through the first outlet 25a provided on the upper surface of the developer conveying / supplying portion 22 on the downstream side in the conveying direction of the developer D. The developer is transported from the developer transport section 26a to the second developer transport section 26b through the second outlet 25b, and further provided on the lower surface of the second developer transport section 26b on the downstream side in the transport direction of the developer D. Through the third outlet 25c, the developer D is guided to the third developer transport section 26c by gravity, and the developer D guided to the third developer transport section 26c is developed through the fourth outlet 25d. Of the developer D in the agent transport and supply unit 22 It has returned to the position of the upstream side feed.

  Further, as in the developing device 20 of the third embodiment shown in FIGS. 9A and 9B, the first developer conveying portion 26 a is extended from the developing roller 21 by the developer conveying and supplying portion 22. A second developer conveying portion 26b having the same length as the first developer conveying portion 26a is provided below the first developer conveying portion 26a. A third developer transport section 26c having the same length as the developer transport supply section 22 is provided in parallel with the second developer transport section 26b and a partition wall, and this third developer transport section is provided. It is also possible to provide 26 c under the developer conveyance supply unit 22.

  In the developing device 20 of the third embodiment, as shown in FIG. 9B, the first outlet 25a provided on the downstream side in the transport direction of the developer D in the developer transport supply unit 22. The developer D guided to is guided to the first developer transport portion 26a through the first outlet port 25a, and the developer D is fed from the first developer transport portion 26a through the second outlet port 25b by gravity. The developer D is guided to the second developer transport section 26b, and the developer D is transported to the third developer through a third outlet 25c provided downstream in the transport direction of the developer D in the second developer transport section 26b. The developer D is guided against the gravity through the fourth outlet 25d provided on the upper surface on the downstream side in the transport direction of the developer D in the third developer transport section 26c. How to transport developer D in supply unit 22 So that the return to the upstream side position.

  In the developing device 20 of the embodiment shown in FIGS. 8A and 8B and FIGS. 9A and 9B, the first device is the same as the developing device 20 in the embodiment. The developer D is transported while being sufficiently stirred in the third three developer transport sections 26a to 26c.

  As a result, in the developing device 20 of the embodiment shown in FIGS. 8A and 8B and FIGS. 9A and 9B, the image in the image forming apparatus is the same as the developing device 20 in the embodiment. Even when the formation speed is increased, the developer D containing the toner and the carrier is sufficiently mixed and stirred, and even when a new toner is replenished, the replenished toner is appropriately charged and used for development. Toner scattering and fogging are prevented from occurring in the formed image, and the developing device 20 is reduced in size and the image forming device is not increased in size.

  In the developing device 20 of each of the above embodiments, the developer D is directly supplied from the developer transport supply unit 22 to the surface of the rotating developing roller 21, but as shown in FIG. It is also possible to supply the developer D in the transport supply unit 22 to the surface of the developing roller 21 via a supply roller (supply member) 29.

  Here, in supplying the developer D in the developer transport and supply unit 22 to the surface of the developing roller 21 through the supply roller 29 in this way, as shown in FIG. The developer D can be supplied to the surface of the developer 21, and the developer D can be supplied from the supply roller 28 to the surface of more developing rollers 21.

  Further, as described above, when the developer D in the developer transport supply unit 22 is supplied to the surface of the developing roller 21 via the supply roller 28, only the toner in the developer D from the supply roller 28 is supplied to the developing roller 21. It is also possible to supply it to the surface.

  Note that the developer D including the toner and the carrier used in the developing device 20 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.

  As the above charge control agent, known ones 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 and barium ferrite containing one or more metals other than iron (Mn, Ni, Mg, Cu, etc.). 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.

10 Photosensitive drum (image carrier)
DESCRIPTION OF SYMBOLS 11 Charging device 12 Latent image forming device 13 Intermediate transfer member 13a Roller 14 Primary transfer device 15 First cleaning device 16 Secondary transfer device 17 Fixing device 18 Second cleaning device 20 Developing device 21 Developing roller (developer carrier)
21a Magnet roller 22 Developer transport supply section 23a, 23b, 23c, 23d Stirring transport member 24 Restriction member 25a, 25b, 25c, 25d Deriving port 26a, 26b, 26c Developer transport section 27a, 27b, 27c, 27d Partition wall 28 Toner Supply port 29 Supply roller D Developer S Recording sheet

Claims (5)

  The developer containing the toner and the carrier is agitated and conveyed, and the developer is conveyed through a developer conveying and supplying unit that supplies the developer to the developer carrying member, and the outlet of the developer conveying and supplying unit on the downstream side in the conveying direction of the developer. A plurality of developer conveying sections that sequentially stir and convey the developer, and a lead-out port that guides the developer to the next developer conveying section on the downstream side of each developer conveying direction in the developer conveying direction. In addition, an outlet for returning the developer to the upstream side in the developer transport direction in the developer transport supply section is provided on the downstream side in the developer transport direction in the final developer transport section. And a developer conveying portion, each of which includes a portion where the developer is led out through the outlet port due to gravity, and a portion where the developer is led out through the outlet port against gravity. At least other than Developing apparatus is characterized in that the developer length of conveyance of the parts is shortened.   2. The developing device according to claim 1, wherein the length of all the developer conveying portions other than the final developer conveying portion is shortened.   3. The developing device according to claim 1, wherein the developer transport portion having a shorter length does not exist in a portion where the developer is supplied to the developer carrying member in the developer transport supply portion. A developing device.   4. The developing device according to claim 1, wherein the developer in the developer transport supply section is used as a developer support between the developer transport supply section and the developer support. A developing device, characterized in that a supply member is provided.   An image forming apparatus using the developing device according to claim 1.

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