JP5800250B2 - Developing device, and image forming apparatus and process cartridge having the same - Google Patents

Description

  The present invention is used in an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and uses a two-component developer composed of a magnetic carrier and a toner to develop a latent image on a latent image carrier, and The present invention relates to an image forming apparatus and a process cartridge having the same.

  This type of developing device is provided with a developer carrier for transporting the developer to a development area facing the latent image carrier. The developer carrying member is, for example, a magnetic field generating means for generating a magnetic field for carrying a magnetic carrier in the developer by a magnetic force on the outer peripheral surface of the developing sleeve inside a cylindrical developing sleeve (hollow body). It has. Toner is electrostatically adsorbed on the magnetic carrier, and by rotating the developing sleeve, the toner is transported to the developing area together with the magnetic carrier carried on the outer peripheral surface of the developing sleeve, and on the latent image carrier in the developing area. Toner is supplied to the latent image. The magnetic field generating means has a plurality of magnetic poles along the rotation direction of the developing sleeve. As such a magnetic field generating means, each magnetic pole forming portion of the roller-shaped integrally formed body is magnetized by an external magnetic field, or individual magnet bodies are used as a common holding body so that the magnetic poles are directed in a predetermined direction. There is something held. The developer carried on the outer peripheral surface of the developing sleeve by the magnetic force of the magnetic field generating means is conveyed in the circumferential direction (surface movement direction) of the developing sleeve by rotating the developing sleeve.

FIG. 28 is a schematic diagram showing an example of a conventional general developing device. In the figure, the alternate long and two short dashes line indicates the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developer carrying member.
In this developing device, a magnet roller (magnetic field generating means) 247 is disposed in a non-magnetic developing sleeve (hollow body) 241 and the developer is carried on the outer peripheral surface of the developing sleeve by the magnetic force of the magnet roller 247 and conveyed. An agent carrier is provided. Further, a developer accommodating portion that accommodates the developer, screw-shaped agitating and conveying members 242 and 243 that convey the developer along the rotation axis direction of the developing sleeve 241 while agitating the developer, and two members carried on the developing sleeve 241. A developer regulating member 246 that regulates the layer thickness of the component developer is also provided. The developer accommodating portion is positioned below the developing sleeve 241 and extends in the axial direction of the developing sleeve 249A, and extends in the axial direction of the developing sleeve adjacent to the first accommodating chamber 249A. The first storage chamber (249A) and the second storage chamber 249B are respectively provided with stirring and conveying members 242 and 243. The developer transported to the downstream end (the rear side in the drawing) of the first storage chamber 249A by the stirring transport member 243 is transferred to the second storage chamber 249B at a location where there is no partition, and the stirring transport member 242 in the second storage chamber. Is conveyed toward the downstream end (the front side in the figure) of the second storage chamber 249B. Then, the developer conveyed to the downstream end of the second storage chamber 249B is transferred to the first storage chamber 249A at a location where there is no partition, and the downstream end of the first storage chamber 249A by the agitation transport member 243 in the first storage chamber. It is conveyed toward. As described above, the developer is circulated and conveyed in the developer accommodating portion. Replenishment toner for replenishing the amount of toner consumed by development is normally supplied to the developer in the second storage chamber 249B. The developer in the first storage chamber 249A is pumped onto the developing sleeve 241 by the magnetic force of the magnet roller 247 during the conveyance. After that, the developer pumped up on the developing sleeve 241 is regulated by the developer regulating member 246, and then passes through the developing region facing the latent image carrier 12, and returns to the developer containing portion again.

  The magnet roller 247 is provided with five poles, S1 (developing pole), N1 (conveying pole), S2 (upper pole out of agent), S3 (outlet of agent / pumping pole), and N2 (regulation pole) ( S1, S2, and S3 have the same polarity and are, for example, S poles, and N1 and N2 are polarities different from S1 and the like, for example, N poles, and so on. As the developing sleeve 241 rotates in the direction of the arrow in the drawing, the developer on the developing sleeve 241 is caused by the rotation of the developing sleeve 241 to run out of the agent / pumping electrode S3, the regulating electrode N2, the developing electrode S1, and the conveying electrode. In this order, N1 and the out-of-agent upstream pole S2 are conveyed so as to pass through the positions facing each magnetic pole. Here, since the developer that has passed through the development region is in a state where toner has been consumed by development, the developer is once peeled off from the development sleeve 241 and returned to the developer accommodating portion, and a new developer is always on the development sleeve 241. It is important to be able to pump up in order to demonstrate stable development ability. In other words, it is important to prevent the developer on the developing sleeve 241 that has passed through the developing area from being conveyed again as it is to the developing area. In the developing device shown in FIG. 28, the out-of-agent upstream pole S2 and the out-of-agent / pumping pole S3 having the same polarity are disposed adjacent to each other, so that the developer on the developing sleeve 241 is located between these magnetic poles. Thus, an agent separation region P in which a peeling force is applied in a direction away from the surface of the developing sleeve 241 is formed. As a result, the developer conveyed to the agent separation area P receives the peeling force due to the magnetic force of the agent run-out upstream pole S2 and the agent run-out / pumping pole S3, and is separated from the developing sleeve 241 and is discharged from the developer accommodating portion. It will be taken into the developer in the one storage chamber 249A.

In the conventional developing device shown in FIG. 28, from the agent separation region P to the restriction position where the developer pumped on the developing sleeve 241 by the magnetic force of the agent running-out / pumping pole S3 is restricted by the developer restriction member 246. On the developing sleeve 241, there is a polarity inflection point Q as shown in the figure. In the vicinity of such an inflection point Q, the magnetic force acting on the developer is relatively strong, and the normal direction magnetic flux density is so small that no spikes occur, so the developer density is high. ing. Therefore, according to this conventional developing device, even if the developer that could not be separated from the developing sleeve 241 in the agent separation region P remains on the developing sleeve 241, the remaining developer remains in the vicinity of the inflection point Q. Since it is scraped off by a high-density developer, there is an advantage that it is possible to effectively prevent the accompanying rotation.
However, as a result of the developer always having a high density in the vicinity of the inflection point Q, a large stress is constantly applied to the developer. Therefore, the torque for driving the stirring / conveying member 243 in the first storage chamber 249A must be increased, and the stirring / conveying member 243 needs to be highly rigid and large, which increases costs and increases the development device. There was a problem that led to an increase in size.
In addition, since the stress applied to the developer is large, the toner charging characteristics and the powder characteristics of the developer deteriorate due to the rapid progress of embedding of the toner additive on the carrier surface and abrasion of the surface film of the carrier. There is also a problem that it is easy to maintain a smooth image quality over a long period of time. In addition, since the powder characteristics of the developer tend to be deteriorated, particularly in the case of a developing sleeve having a low conveyance capability, the amount of the developer conveyed to the development area is likely to decrease, and the image density can be maintained over a long period of time. There is also a problem that it is difficult.

Patent Document 1 discloses a developing device as shown in FIG. 29 for the purpose of reducing the stress applied to the developer. In this developing device, a single magnetic pole (agent running out / pumping) that simultaneously plays the role of these magnetic poles instead of the agent running out / pumping pole S3 and the regulating pole N2 in the conventional developing device shown in FIG. A regulation electrode is provided, and this is disposed in the vicinity of the developer regulation member 346. As a result, according to the description of Patent Document 1, the developer sleeve 341 in the developer transport direction with respect to the restriction position by the developer restriction member 346 (hereinafter simply referred to as “upstream” and “downstream”) The developer that cannot be pumped up at the above-mentioned agent run-out, pumping-up, or regulating electrode N3 quickly falls onto the stirring and transporting screw 343. Therefore, it is described that a large accumulation of developer does not occur in the region, and stress on the developer can be reduced.
Also, Patent Document 2 discloses a developing device in which the above-described agent run-out / pumping / regulating electrode N3 is disposed in the vicinity of the developer regulating member 346. This developing device can also reduce the stress on the developer for the same reason.

  Patent Document 3 discloses a metal member having a hollow extending in a direction orthogonal to the developer carrier surface movement direction in order to suppress a temperature rise of the developer in the vicinity of the developer regulating member. And a developing device provided with cooling means for cooling the developer regulating member from its hollow side is disclosed.

  However, in the developing devices described in Patent Document 1 and Patent Document 2, since the developer accumulation in the region upstream of the restriction position by the developer restriction member 346 is reduced, image density unevenness may occur. There was a problem. The present inventors have studied the cause and elucidated the cause.

That is, in these developing devices, when the developer after development is detached from the developing sleeve 341 in the agent separation region P and dropped onto another developer in the first storage chamber (supply chamber) 349A, the developer is stirred and conveyed. While being agitated with another developer by the screw 343, the first accommodation chamber is conveyed along the developing sleeve in the axial direction thereof. At this time, the developed developer that has dropped onto the other developer in the first storage chamber (supply chamber) 349A may be immediately pumped up by the above-mentioned agent running out, pumping up, and magnetic force of the regulating pole N3. In this case, the developer is not sufficiently mixed with the developer after development and the other developer, that is, the developer portion having a low toner concentration and the developer portion having a high toner concentration. While coexisting, it moves to the restriction position.
Unlike the developing device as shown in FIG. 29, in the case of the developing device shown in FIG. 28, the high-density developer stays in the vicinity of the inflection point Q in the upstream region of the restricting position, so that it has been pumped up. When the developer passes through the staying region, the developer is mixed with the staying developer in a high stress state. Therefore, even if the developer after development is mixed with another developer without being sufficiently mixed, the toner density deviation of the developer is equalized in the staying area, so that image density unevenness does not occur. There are few. However, in the developing apparatuses described in Patent Document 1 and Patent Document 2 as shown in FIG. 29, as described above, the developer does not stay much in the upstream region of the restriction position, so in the upstream region of the restriction position. The leveling effect of the developer toner density deviation is hardly obtained. Therefore, when the developed developer that has fallen onto the other developer in the first storage chamber (supply chamber) 349A is immediately pumped up, the developer portion in a state where the toner concentration is low and the state where the toner concentration is high The developer portion passes through the regulation position while being coexisting with the developer portion, and is conveyed to the development region, and image density unevenness is likely to occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce image density unevenness while realizing low stress of the developer in the upstream region of the restriction position by the developer restriction member. It is an object of the present invention to provide a developing device, an image forming apparatus and a process cartridge including the developing device.

In order to achieve the above object, the invention of claim 1 is characterized in that the magnetic field generating means is arranged in a non-magnetic hollow body and a two-component developer comprising a magnetic carrier and toner is carried on the outer peripheral surface of the hollow body. A developer carrying member to be transported; a developer containing portion containing a supply chamber containing a two-component developer carried on the developer carrying member; and a rotational axis direction of the developer carrying member for the two-component developer. And a developer regulating member for regulating the layer thickness of the two-component developer carried on the developer carrying member, and from above the developer containing portion on the developer carrying member. In the developing device in which the two-component developer carried on the substrate is regulated by the developer regulating member and then passed through the development region facing the latent image carrier and returned again into the developer accommodating portion, the magnetic field generating means is adjacent to With first and second magnetic poles of the same polarity, The second magnetic pole is disposed downstream of the first magnetic pole in the developer transport direction by the developer carrier and in the vicinity of the developer regulating member, and two-component development is performed from the supply chamber in the developer accommodating portion. agent pumping and a two-component developer in the developer carried on body is regulated by the developer regulating member is intended to produce a magnetic force for causing the ears, in the developer conveyance direction upstream side by the current image carrying member end regulating surface of said developer regulating member, the than normal of the point where the maximum normal magnetic flux density on said developer carrying member according to the second magnetic pole, the developer conveyance by the developer carrying member The developer regulating member is arranged so as to be downstream in the direction, and the agitating and conveying member in the supply chamber in the developer accommodating portion is driven to rotate in the same direction as the rotation direction of the developer carrying member. At the top of the agitating and conveying member Force direction position is arranged to be positioned with the gravitational direction gap below the gravity direction position of the lower end of the developer carrying member, said first magnetic pole in the developer carrying member and the second magnetic pole The developer in the agent separation region between the outer periphery of the stirring carrier member falls into the supply chamber on the side where the outer peripheral portion of the stirring carrier member moves from the upper side to the lower side with respect to the rotation center axis of the stirring carrier member. The developer on the side where the outer peripheral portion of the stirring and conveying member moves from the lower side to the upper side with respect to the rotation center axis is pumped to the downstream side in the developer conveying direction by the developer carrier from the agent separation region. Between the rotation center axis of the agitating and conveying member and the outer periphery of the agitating and conveying member, an agent separation region is arranged above the gravity direction, and the magnetic member having a thin plate portion is developed with respect to the developer regulating member. The upstream side of the developer transport direction by the developer carrier The plate of the thin plate portion disposed on the outer side of the outer peripheral surface of the image carrier between the gravity direction position of the lower end and the gravity direction position of the upper end of the agitation transport member on the upstream side in the developer transport direction by the developer carrier. The end of the surface is located upstream of the normal line at the point where the normal magnetic flux density by the second magnetic pole is maximum on the developer carrier in the developer transport direction by the developer carrier. and it is characterized in the this arranged the magnetic member.
According to a second aspect of the present invention, in the developing device of the first aspect, the magnetic member has one plate surface portion obtained by bending the thin plate portion as an opposing surface facing the second magnetic pole, The plate surface portion is used as a joint surface with respect to the developer restricting member, and the joint surface of the magnetic member is on the upstream side surface of the developer restricting member facing the upstream side in the developer transport direction by the developer carrier. The magnetic member is fixed to the developer regulating member by bonding.
According to a third aspect of the present invention, in the developing device according to the first aspect, the magnetic member is a hollow member provided therein with a hollow region extending in a rotation axis direction of the developer carrier. A portion of the member facing the second magnetic pole constitutes the thin plate portion, and has cooling means for cooling the magnetic member by moving the heat in the hollow region of the magnetic member to the outside of the hollow region. It is characterized by this.
According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, the developer regulating member is non-magnetic.
According to a fifth aspect of the present invention, in the developing device according to any one of the first to fourth aspects, the developer regulating member is disposed vertically below the developer carrier. It is characterized by.
According to a sixth aspect of the present invention, in the developing device according to any one of the first to fifth aspects, the hollow body is provided with a large number of elliptical recesses on the outer peripheral surface thereof at random. It is characterized by this.
According to a seventh aspect of the present invention, a latent image carrier and a two-component developer comprising a magnetic carrier and a toner are conveyed to a development area facing the latent image carrier to form a latent image on the latent image carrier. A developing device that attaches and develops the toner is integrally supported, and the toner image obtained by the development by the developing device is finally transferred from the latent image carrier onto the recording material, so that A developing device according to any one of claims 1 to 6 is used as the developing device in a process cartridge that is detachable from an image forming apparatus that forms an image.
Further, the invention of claim 8 provides a latent image bearing member and a latent image on the latent image bearing member by transporting a two-component developer comprising a magnetic carrier and a toner to a developing area facing the latent image bearing member. A developing device that attaches and develops the toner, and finally transfers the toner image obtained by development by the developing device from the latent image carrier onto the recording material, whereby an image is formed on the recording material. In the image forming apparatus to be formed, the developing device according to any one of claims 1 to 6 is used as the developing device.
According to a ninth aspect of the present invention, in the image forming apparatus of the eighth aspect, the weight average particle diameter of the magnetic carrier is 20 [μm] or more and 65 [μm] or less.
According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect, the magnetization intensity of the magnetic carrier in a 1 × 10 ⁶ / 4π [A / m] magnetic field is 40 [A · m ² / kg] or more and 90 [A · m ² / kg] or less.
The invention according to claim 11 is the image forming apparatus according to any one of claims 8 to 10, wherein the toner has a volume average particle diameter of 3 μm or more and 8 μm or less, and a volume average particle diameter (Dv). And a number average particle diameter (Dn) ratio (Dv / Dn) is in the range of 1.00 to 1.40.
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the eighth to eleventh aspects, as the toner, the shape factor SF-1 is in the range of 100 to 180, and the shape factor SF-2. Is in the range of 100-180.
The invention according to claim 13 is the image forming apparatus according to any one of claims 8 to 12, wherein the toner includes a polyester prepolymer having at least a functional group containing a nitrogen atom, a polyester, a colorant, It is a toner obtained by crosslinking and / or extending reaction of a toner material liquid in which a release agent is dispersed in an organic solvent in an aqueous medium.
The invention of claim 14 is the image forming apparatus according to any one of claims 8 to 13, wherein the shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3. R1 ≧ r2 ≧ r3)), the ratio of the major axis r1 to the minor axis r2 (r2 / r1) is in the range of 0.5 to 1.0, and the ratio of the thickness r3 to the minor axis r2 ( r3 / r2) is in the range of 0.7 to 1.0.

In the present invention, since the second magnetic pole having the same polarity as the first magnetic pole and adjacent to the first magnetic pole is disposed in the vicinity of the developer regulating member, the developer pumped on the developer carrying member is regulated by the developer. There is no inflection point of the magnetic field on the developer carrier until it is regulated by the member. Therefore, like the above-described developing device shown in FIG. 29, the developer stress can be reduced as compared with the conventional device in which such an inflection point exists.
In the present invention, the magnetic member is disposed outside the outer peripheral surface of the developer carrying member on the upstream side (hereinafter simply referred to as “upstream”) of the developer carrying member by the developer carrying member with respect to the developer regulating member. are, the plate surface of the thin plate portion having its magnetic member (hereinafter referred to as "magnetic plate surface".) will suited to the second pole. Specifically, for example, when the magnetic plate surface is a flat surface, the surface direction is substantially parallel to the tangential direction in the region on the developer carrier where the normal magnetic flux density by the second magnetic pole exists. In addition, a magnetic plate surface is disposed with respect to the second magnetic pole. In the region between the magnetic plate surface and the second magnetic pole, the magnetic flux is concentrated as compared to the case where the magnetic plate surface is not present (hereinafter, this region is referred to as “magnetic field concentration region”). ). For this reason, in the magnetic field concentration region located upstream of the restriction position of the developer restriction member in the developer accommodating portion, the developer can be restrained by a stronger magnetic force than when no magnetic plate surface is present. Here, most of the developer passing through the restriction position by the developer restriction member is a developer portion carried near the surface of the developer carrier, and is carried at a position away from the surface of the developer carrier. The developer portion is restricted from passing through the restriction position by the developer restriction member. In the conventional apparatus having no magnetic material plate surface as described above, the developer conveyed along with the movement of the surface of the developer carrier passes through the restriction position when passing the upstream region of the developer restriction member. There were few things that could hinder the movement of the developer carried near the surface of the developer carrying body. On the other hand, in the present invention, when the developer conveyed along with the surface movement of the developer carrying member enters the magnetic field concentration region on the upstream side of the developer regulating member, the developer near the surface is It collides with the developer already constrained in the magnetic field concentration region, or is constrained by the magnetic field in the magnetic field concentration region, and moves in the magnetic field concentration region while being prevented from proceeding. At this time, since the degree of hindering the progress of the developer in the magnetic field concentration region differs depending on the individual developer, the time required to pass through the magnetic field concentration region also varies depending on the individual developer. As a result, even if a developer having a remarkable toner density deviation is conveyed to the magnetic field concentration area, the toner density deviation is leveled after passing through the magnetic field concentration area, and the deviation can be reduced. Conceivable. In addition, the traveling direction may be changed due to collision with a developer that is already constrained in the magnetic field concentration region, but the direction in which the change is made, the degree of change, and the like are different for each developer. This also contributes to the effect of leveling out the toner density deviation of the developer, and the deviation can be improved.

Here, in the developing device described in Patent Document 1, the plate surface (sheet surface) of a thin flat plate-like magnetic body (magnetic sheet) is joined to the upstream side surface of the developer regulating member, and the end surface of the magnetic sheet is formed. Is configured so as to be directed to the second magnetic pole. In this developing device, since the magnetic field concentrates between the end face of the magnetic sheet and the second magnetic pole, the developer in the region where the magnetic field concentrates behaves in the same manner as in the magnetic field concentration region in the present invention. It is guessed. However, in the configuration like the developing device described in Patent Document 1, the length of the region where the magnetic field between the end face of the magnetic sheet and the second magnetic pole concentrates (the length in the developer conveyance direction by the developer carrier). ) Is too short, the effect of leveling out the toner density deviation of the developer cannot be obtained effectively, resulting in uneven image density.
On the other hand, if an attempt is made to increase the length of the magnetic field concentration region between the end face of the magnetic material sheet and the second magnetic pole by increasing the thickness of the magnetic material sheet in the developing device described in Patent Document 1, the magnetic material is It will become huge. In this way, when a huge magnetic body exists in the upstream region of the developer regulating member, the magnetic body greatly disturbs the magnetic field on the outer peripheral surface of the developer carrying body, and developer conveyance failure due to the developer carrying body or the developer Adverse effects such as poor pumping.
On the other hand, in the present invention, the length of the magnetic field concentration region in the upstream region of the developer regulating member can be increased without enlarging the magnetic member itself, so that the developer by the developer carrying member can be increased. The toner density deviation of the developer can be leveled sufficiently without adverse effects such as conveyance failure and developer pumping failure, and image density unevenness can be effectively reduced.

  According to the present invention, there is an excellent effect that unevenness in image density can be reduced while realizing low stress of the developer in the upstream region of the restriction position by the developer restriction member.

1 is a schematic configuration diagram of a printer according to Embodiment 1. FIG. It is a schematic block diagram which shows the yellow image forming apparatus. FIG. 4 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-1. FIG. 6 is a diagram schematically illustrating the shape of a toner for explaining a shape factor SF-2. It is a perspective view which shows the external appearance of the developing device of yellow. FIG. 6 is a perspective view of a state where the upper casing is removed so that the inside of the developer accommodating portion of the developing device can be visually recognized. It is explanatory drawing which showed the distribution of the normal direction magnetic flux density (absolute value) on the surface of a developing sleeve with the schematic structure of the developing device with the dashed-two dotted line. 6 is a graph showing a normal direction magnetic flux density (thin line) on the surface of the developing sleeve in the vicinity of the agent separation region of the developing device and a normal direction magnetic force (thick line) on the surface of the developing sleeve. It is a graph which shows the normal direction magnetic flux density (thin line) on the developing sleeve surface in the periphery of the agent separation area of the comparison device, and the normal direction magnetic force (thick line) on the developing sleeve surface. It is explanatory drawing of the magnetization process at the time of manufacturing the magnet roller of the developing device of Embodiment 1. FIG. It is explanatory drawing of the magnetization process at the time of manufacturing the magnet roller of a comparison apparatus. 10 is a graph showing a normal direction magnetic flux density (thin line) on the surface of the developing sleeve in the vicinity of the agent separation region of Modification 1 and a normal direction magnetic force (thick line) on the surface of the developing sleeve. (A) is a graph which shows the normal direction magnetic flux density (thin line) on the surface of the developing sleeve in the periphery of the agent separation region of Modification 2 and the normal direction magnetic force (thick line) on the surface of the developing sleeve. (B) shows the normal direction magnetic flux density (thin line) on the surface of the developing sleeve in the vicinity of the agent separation area of the apparatus created for comparison with the modified example 2, and the normal direction magnetic force (thick line) on the surface of the developing sleeve. It is a graph which shows. FIG. 6 is an explanatory diagram illustrating an arrangement example of magnets in a developer conveying direction by a developing sleeve in the developing device of Embodiment 1. FIG. 6 is an explanatory diagram showing an example of arrangement of magnets in the developing sleeve axial direction in the developing device. It is explanatory drawing which shows a shape when the doctor blade in the developing device is seen from the developing sleeve axial direction. (A) is explanatory drawing which shows the behavior of the developer of the doctor blade upstream in the developing device. (B) is explanatory drawing which shows the behavior of the developer of the doctor blade upstream in the conventional developing device. It is a graph for demonstrating the pumping change rate by arrangement | positioning of the control position by the doctor blade. It is explanatory drawing which shows magnetic force distribution of the control position vicinity by the doctor blade. It is a graph which shows the result of having measured the pumping amount with respect to a doctor gap about the case where the control position by a doctor blade is changed with respect to the magnetic pole of a magnet roller. It is explanatory drawing which shows the modification of the attachment position of a magnetic body member. It is explanatory drawing which shows the other shape of a doctor auxiliary member. 6 is an external perspective view of a developing device according to Embodiment 2. FIG. FIG. 6 is a perspective view of a state where the upper casing is removed so that the inside of the developer accommodating portion of the developing device can be visually recognized. FIG. 2 is a diagram illustrating a schematic configuration of the developing device, and is a view when viewed from a developing sleeve axial direction. FIG. 10 is an explanatory diagram showing a shape of a hollow member arranged on the upstream side of the doctor blade in Embodiment 3 when viewed from the axial direction of the developing sleeve and the behavior of the developer on the upstream side of the doctor blade. It is a schematic block diagram which shows the example which improved the hollow member. It is a schematic block diagram which shows the example of the conventional general developing apparatus. It is a schematic block diagram which shows the example which improved the developing device. (A) is explanatory drawing which shows the mode of the developer which rose with the magnetic force of N3 pole in the developing device of embodiment. (B) is explanatory drawing which shows the mode of the developer which rose with the magnetic force of N3 pole in the conventional developing device shown in FIG.

Embodiment 1
Hereinafter, an embodiment (hereinafter, this embodiment is referred to as “embodiment 1”) in which the present invention is applied to an electrophotographic printer (hereinafter simply referred to as “printer”) as an image forming apparatus will be described. .
FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. Y, C, M, and K indicate members for yellow, cyan, magenta, and black, respectively.
In this printer, image forming apparatuses 10Y, 10C, 10M, and 10K for four colors as process cartridges are detachable from an image forming station (not shown) formed on the apparatus main body 1 side. These use Y, M, C, and K toners of different colors as the image forming material, but the other configurations are the same and are replaced when the lifetime is reached. The printer further includes an optical unit 20, an intermediate transfer body unit 30, a paper feed unit 40, a fixing unit 50, and the like as exposure means capable of irradiating laser light.

The image forming apparatuses 10Y, 10C, 10M, and 10K have the same structure, and the photosensitive drums 12Y, 12C, 12M, and 12K as latent image carriers are charged, and the photosensitive drums are charged as process means that act on the photosensitive drums. The charging devices 13Y, 13C, 13M, and 13K, and the cleaning devices 15Y, 15C, 15M, and 15K for removing the toner remaining on the photosensitive drum are integrally configured, and formed on each photosensitive drum. The developing devices 14Y, 14C, 14M, and 14K for developing the latent images are connected.
The intermediate transfer body unit 30 is formed on an intermediate transfer belt 31 as an intermediate transfer body, a plurality of (here, three) rollers 32, 33, and 34 that rotatably support the intermediate transfer belt 31, and each photosensitive drum 12. A primary transfer roller 35 for transferring the toner image to the intermediate transfer belt 31, and a secondary transfer roller 36 for transferring the toner image transferred onto the intermediate transfer belt 31 to a recording paper P as a recording material. .
The paper supply unit 40 includes a paper supply roller 43 that conveys the recording paper P from the paper supply cassette 41 or the manual paper supply tray 42 to the secondary transfer region, a registration roller 44, and the like.
The fixing unit 50 includes a fixing roller 51 and a pressure roller 52, and has a known configuration in which fixing is performed by applying heat and pressure to the toner image on the recording paper P.

  In addition, toner bottles 60Y, 60C, 60M, and 60K that store toner to be supplied to a toner supply port 145, which will be described later, are provided on the upper portion of the apparatus main body 1 separately from the image forming apparatuses 10Y, 10C, 10M, and 10K. The main body 1 is detachably mounted.

  In such a configuration, first, in the first color yellow image forming device 10Y, after the photosensitive drum 12Y is uniformly charged by the charging device 13Y, the laser light emitted from the optical unit 20 as the latent image forming means. Thus, the latent image is developed by the developing device 14Y to form a toner image. The Y toner image formed on the photosensitive drum 12Y is transferred onto the intermediate transfer belt 31 by the action of the primary transfer roller 35Y. The photosensitive drum 12Y after the primary transfer is cleaned by the cleaning device 15Y to prepare for the next image formation. The residual toner collected by the cleaning device 15Y is stored in a waste toner collection bottle 16 installed in the take-out direction of the image forming device 10Y (the rotation axis direction of the photosensitive drum). The waste toner collection bottle 16 is detachable from the image forming apparatus main body 1 so that it can be replaced when the storage amount is full. A similar image forming process is performed in each of the image forming apparatuses 10C, 10M, and 10K for C, M, and K to form toner images of the respective colors, and are sequentially transferred to the previously formed toner images. On the other hand, the toner image formed on the intermediate transfer belt 31 is transferred to the recording paper P conveyed from the paper feed cassette 41 or the manual paper feed tray 42 to the secondary transfer region by the action of the secondary transfer roller 36. . The recording paper P to which the toner image has been transferred is conveyed to the fixing unit 50, where the toner image is fixed at the nip portion between the fixing roller 51 and the pressure roller 52 of the fixing unit 50, and the discharge roller 55 discharges the upper part of the apparatus. The paper is discharged to the paper tray 56.

Next, a specific configuration of the image forming apparatus will be described.
Since the configurations of the image forming apparatuses 10Y, 10C, 10M, and 10K are the same except that the color of the toner to be used is different, the yellow image forming apparatus 10Y will be described below as an example.
FIG. 2 is a schematic configuration diagram showing an image forming apparatus 10Y for generating a Y toner image.
The charging device 13Y provided in the image forming device 10Y includes a charging roller 131 and a cleaning roller 132 that cleans the surface of the charging roller 131. The cleaning device 15Y includes a cleaning brush 151 and a cleaning blade 152 that are in contact with the surface of the photosensitive drum, and a toner recovery coil 153 that transports the toner scraped off by the cleaning brush 151 and the cleaning blade 152 toward the waste toner recovery bottle 16. I have.

  The developing device 14Y carries a two-component developer (hereinafter simply referred to as “developer”) made of a magnetic carrier and toner, and rotates and moves counterclockwise in FIG. 2 to a developing area facing the photosensitive drum 12Y. A non-magnetic developing sleeve 141 constituting a hollow body of the developer carrying member to be conveyed is provided. Inside the developing sleeve 141, a magnet roller 147 is fixedly disposed as magnetic field generating means having a plurality of magnetic poles in the circumferential direction. A developer carrier is constituted by the developing sleeve 141 and the magnet roller 147. Further, as a developer regulating member for forming a doctor gap S between the developing sleeve 141 and the developing sleeve 141, the doctor gap S for regulating the layer thickness of the toner carried on the developing sleeve 141 is defined. The doctor blade 146 is also provided. Further, two agitation and conveying members for reciprocally conveying the magnetic carrier accommodated in the developing device 14Y and the replenishment toner supplied from the toner replenishing port 145 in the axial direction of the photosensitive drum 12Y. Conveying screws 142 and 143 are also provided. These members are housed and supported in the developing casing 144. In particular, the doctor blade 146 is supported so as to be sandwiched between the developing casings 144.

  Supplementing the doctor blade 146, the doctor blade 146 of this embodiment is composed of a doctor base 146a formed of a nonmagnetic member and a doctor auxiliary member 146b formed of a magnetic member. The doctor base 146a mainly functions to restrict the amount of developer conveyed to the development area to a certain fixed amount, and the developer base 146a receives the developer pressure when the developer is restricted. Therefore, in general, the doctor base 146a must have a thickness (a length corresponding to the developer conveying direction by the developing sleeve) of, for example, about 1.5 to 2 mm in order to ensure a certain level of strength. In addition, a straightness of about 0.05 mm is required at the tip end (the end facing the developing sleeve surface). On the other hand, the doctor auxiliary member 146b mainly fulfills the function of increasing the charge amount of the toner conveyed to the development area, and is usually much thinner than the doctor base 146a, for example, about 0.2 mm in thickness. It is formed of a flat sheet metal. The doctor auxiliary member 146b needs to maintain the positional relationship with the surface of the developing sleeve with high accuracy in the axial direction of the developing sleeve in order to make the toner charging property uniform in the axial direction of the developing sleeve. Therefore, the doctor auxiliary member 146b is attached to the doctor base 146a by spot welding, caulking, or the like.

  As the toner of this embodiment, a toner having a circularity of 0.93 or more can be used. In other words, it is known to reduce the toner particle size in order to improve the image quality of the image, but in the case of reducing the particle size, the conventional pulverized toner has a particle size distribution that is broad. There is a characteristic that it is difficult. For this reason, a method for realizing high image quality by increasing the circularity of the toner by a polymerization method or the like and having a sharp particle size distribution has become common. The toner of the present embodiment is obtained by dispersing a toner composition comprising at least a prepolymer, a colorant, and a release agent in an aqueous medium in the presence of resin fine particles, and subjecting the toner composition to a polyaddition reaction. Polymerized toner is used. By using such a toner, there are no pulverization steps, resource saving can be achieved, particle size distribution and charge distribution can be sharpened, and shape control that changes the circularity can be easily performed. Can be obtained.

Further, as the toner of the present exemplary embodiment, a toner having a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180 is preferable.
3 and 4 are diagrams schematically showing the shape of the toner for explaining the shape factor SF-1 and the shape factor SF-2, respectively.
The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) ² / AREA} × (100π / 4) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated.
When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photosensitive drum 12 becomes a point contact. The attracting force with the photosensitive drum 12 is also weakened, and the transfer rate is increased. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

In addition, the shape of the toner of the present embodiment is preferably substantially spherical, and can be represented by the following shape rule.
When a substantially spherical toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), the toner in this embodiment has a ratio of a major axis to a minor axis ( r2 / r1) is preferably 0.5 to 1.0, and the ratio of thickness to minor axis (r3 / r2) is preferably in the range of 0.7 to 1.0. When the ratio of the major axis to the minor axis (r2 / r1) is less than 0.5, the dot reproducibility and transfer efficiency are inferior because of being away from the true spherical shape, and high-quality image quality cannot be obtained. On the other hand, if the ratio of thickness to minor axis (r3 / r2) is less than 0.7, the shape is close to a flat shape, and a high transfer rate like a spherical toner cannot be obtained. In particular, when the ratio of the thickness to the minor axis (r3 / r2) is 1.0, the rotating body has a major axis as a rotation axis, and the fluidity of the toner can be improved. Note that r1, r2, and r3 were measured with a scanning electron microscope (SEM) while changing the angle of field of view and taking pictures.

  Further, as the toner of the present exemplary embodiment, it is preferable to use a toner having a volume average particle diameter of 3 μm or more and 8 μm or less in order to reproduce minute dots of 600 dpi or more. The ratio (Dv / Dn) between the volume average particle diameter (Dv) and the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer this ratio (Dv / Dn) is to 1.00, the sharper the particle size distribution. If the toner has such a small particle size and a narrow particle size distribution, the toner charge amount distribution can be easily made uniform, and a high-quality image with little background fogging can be obtained. Can be high.

  A toner suitably used in the exemplary embodiment includes a toner material liquid in which at least a polyester prepolymer having a functional group containing a nitrogen atom, polyester, a colorant, and a release agent is dispersed in an organic solvent in an aqueous solvent. Is a toner obtained by crosslinking and / or elongation reaction. Hereinafter, the constituent material and the manufacturing method of the toner will be described.

(polyester)
The polyester is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound. Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO) preferable. Examples of the dihydric alcohol (DIO) include alkylene glycol (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycol (diethylene glycol) , Triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol) F, bisphenol S, etc.); alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adduct of the above alicyclic diol; Alkylene oxide bisphenol (ethylene oxide, propylene oxide, butylene oxide, etc.), etc. adducts. Among them, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms. It is a combined use. The trihydric or higher polyhydric alcohol (TO) includes 3 to 8 or higher polyhydric aliphatic alcohols (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); trihydric or higher phenols (Trisphenol PA, phenol novolak, cresol novolak, etc.); and alkylene oxide adducts of the above trivalent or higher polyphenols.

  Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone and (DIC) with a small amount of (TC) Mixtures are preferred. Divalent carboxylic acids (DIC) include alkylene dicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylene dicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid) And naphthalenedicarboxylic acid). Of these, preferred are alkenylene dicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms. Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid). In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the above-mentioned acid anhydride or lower alkyl ester (Methyl ester, ethyl ester, isopropyl ester, etc.).

  The ratio of the polyhydric alcohol (PO) to the polycarboxylic acid (PC) is usually 2/1 to 1/1, preferably as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Is 1.5 / 1 to 1/1, more preferably 1.3 / 1 to 1.02 / 1. The polycondensation reaction between a polyhydric alcohol (PO) and a polycarboxylic acid (PC) is carried out in the presence of a known esterification catalyst such as tetrabutoxytitanate or dibutyltin oxide, and heated to 150 to 280 ° C. while reducing the pressure as necessary. The produced water is distilled off to obtain a polyester having a hydroxyl group. The hydroxyl value of the polyester is preferably 5 or more, and the acid value of the polyester is usually 1 to 30, preferably 5 to 20. By giving an acid value, it tends to be negatively charged, and furthermore, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixability is improved. However, when the acid value exceeds 30, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation. The weight average molecular weight is 10,000 to 400,000, preferably 20,000 to 200,000. A weight average molecular weight of less than 10,000 is not preferable because offset resistance deteriorates. On the other hand, if it exceeds 400,000, the low-temperature fixability is deteriorated.

  In addition to the unmodified polyester obtained by the above polycondensation reaction, the polyester preferably contains a urea-modified polyester. The urea-modified polyester is obtained by reacting a terminal carboxyl group or hydroxyl group of the polyester obtained by the above polycondensation reaction with a polyvalent isocyanate compound (PIC) to obtain a polyester prepolymer (A) having an isocyanate group. It is obtained by cross-linking and / or extending the molecular chain by the reaction of the amine with amines.

Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.) ); Aromatic diisocyanates (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); araliphatic diisocyanates (α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.); isocyanates; Those blocked with caprolactam or the like; and combinations of two or more of these.
The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When [NCO] / [OH] exceeds 5, low-temperature fixability deteriorates. When the molar ratio of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered and hot offset resistance is deteriorated.
The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is usually 0.5 to 40 wt%, preferably 1 to 30 wt%, more preferably 2 to 20 wt%. . If it is less than 0.5 wt%, the hot offset resistance deteriorates, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. On the other hand, if it exceeds 40 wt%, the low-temperature fixability deteriorates.
The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is usually 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. If it is less than 1 per molecule, the molecular weight of the urea-modified polyester will be low, and the hot offset resistance will deteriorate.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), and amino acid block of B1 to B5 (B6).
Examples of the divalent amine compound (B1) include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane, etc.); alicyclic diamines (4,4′-diamino-3,3′-dimethyldicyclohexyl). Methane, diamine cyclohexane, isophorone diamine, etc.); and aliphatic diamines (ethylene diamine, tetramethylene diamine, hexamethylene diamine, etc.) and the like.
Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine. Examples of amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan.
Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of the compound (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.
The ratio of amines (B) is equivalent to the equivalent ratio [NCO] / [NHx] of isocyanate groups [NCO] in the polyester prepolymer (A) having isocyanate groups and amino groups [NHx] in amines (B). Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] is more than 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance is deteriorated.

The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio of the urea bond content to the urethane bond content is usually 100/0 to 10/90, preferably 80/20 to 20/80, and more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance is deteriorated.
The urea-modified polyester is produced by a one-shot method or the like. Polyhydric alcohol (PO) and polyvalent carboxylic acid (PC) are heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxytitanate, dibutyltin oxide, etc., and water generated while reducing the pressure as necessary. Distill off to obtain a polyester having a hydroxyl group. Subsequently, at 40-140 degreeC, this is made to react with polyvalent isocyanate (PIC), and the polyester prepolymer (A) which has an isocyanate group is obtained. Further, this (A) is reacted with amines (B) at 0 to 140 ° C. to obtain a urea-modified polyester.

  When reacting (PIC) and when reacting (A) and (B), a solvent may be used if necessary. Usable solvents include aromatic solvents (toluene, xylene, etc.); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.); esters (ethyl acetate, etc.); amides (dimethylformamide, dimethylacetamide, etc.) and ethers And those inert to isocyanates (PIC), such as tetrahydrofuran (such as tetrahydrofuran). In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.), and those obtained by blocking them (ketimine compounds). The weight average molecular weight of the urea-modified polyester is usually 10,000 or more, preferably 20,000 to 10,000,000, and more preferably 30,000 to 1,000,000. If it is less than 10,000, the hot offset resistance deteriorates. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight. When the urea-modified polyester is used alone, its number average molecular weight is usually 2000-15000, preferably 2000-10000, more preferably 2000-8000. When it exceeds 20000, the low-temperature fixability and the glossiness when used in a full-color apparatus are deteriorated. By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the gloss when used in the full-color image forming apparatus 100 are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond. The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition. The weight ratio of unmodified polyester to urea-modified polyester is usually 20/80 to 95/5, preferably 70/30 to 95/5, more preferably 75/25 to 95/5, and particularly preferably 80 /. 20-93 / 7. When the weight ratio of the urea-modified polyester is less than 5%, the hot offset resistance is deteriorated, and it is disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability. The glass transition point (Tg) of the binder resin containing unmodified polyester and urea-modified polyester is usually 45 to 65 ° C, preferably 45 to 60 ° C. If it is less than 45 ° C., the heat resistance of the toner deteriorates, and if it exceeds 65 ° C., the low-temperature fixability becomes insufficient. In addition, since the urea-modified polyester is likely to be present on the surface of the obtained toner base particles, the heat-resistant storage stability tends to be good even when the glass transition point is low as compared with known polyester-based toners.

(Coloring agent)
As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher , Yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Sayred, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine B, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R , Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thio Indigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red Polyazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Lid Russian nin green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used.
The content of the colorant is usually 1 to 15% by weight, preferably 3 to 10% by weight, based on the toner. The colorant can also be used as a master batch combined with a resin. As a binder resin to be kneaded together with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyl toluene or the like, or a copolymer of these and a vinyl compound, Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes and the like can be mentioned, and these can be used alone or in combination.

(Charge control agent)
Known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (fluorine-modified 4 Secondary ammonium salts or compounds, tungsten simple substances or compounds, fluorine activators, salicylic acid metal salts, and metal salts of salicylic acid derivatives. Specifically, Bontron 03 of a nigrosine dye, Bontron P-51 of a quaternary ammonium salt, Bontron S-34 of a metal-containing azo dye, E-82 of an oxynaphthoic acid metal complex, E-84 of a salicylic acid metal complex , Phenolic condensate E-89 (above, Orient Chemical Industries, Ltd.), quaternary ammonium salt molybdenum complex TP-302, TP-415 (above, Hodogaya Chemical Co., Ltd.), quaternary ammonium salt copy Charge PSYVP2038, copy blue PR of triphenylmethane derivative, quaternary ammonium salt copy charge NEGVP2036, copy charge NXVP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (manufactured by Nippon Carlit) Copper phthalocyanine, perylene, quinacridone, azo pigments Sulfonate group, a carboxyl group, and polymer compounds having a functional group such as quaternary ammonium salts. Of these, substances that control the negative polarity of the toner are particularly preferably used.
The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 0.2 to 5 parts by weight is preferable. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is lowered, and the image density is lowered. Invite.

(Release agent)
As a release agent, a low melting point wax having a melting point of 50 to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. The effect on high temperature offset is exhibited without applying a release agent such as oil. Examples of such a wax component include the following. Examples of waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, rice wax, animal waxes such as beeswax and lanolin, mineral waxes such as ozokerite and cercin, and paraffin, microcrystalline, And petroleum waxes such as petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A crystalline polymer having a long alkyl group in the side chain such as a homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.) can also be used. .
The charge control agent and the release agent can be melt-kneaded together with the master batch and the binder resin, and of course, they may be added when dissolved and dispersed in the organic solvent.

(External additive)
Inorganic fine particles are preferably used as an external additive for assisting the fluidity, developability and chargeability of the toner particles. The primary particle diameter of the inorganic fine particles is preferably 5 × 10 −3 to 2 μm, and particularly preferably 5 × 10 −3 to 0.5 μm. Moreover, it is preferable that the specific surface area by BET method is 20-500 m < ² > / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5 wt% of the toner, and particularly preferably 0.01 to 2.0 wt%.
Specific examples of the inorganic fine particles include, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, quartz sand, clay, mica, wollastonite, diatomaceous earth. Examples include soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, as the fluidity imparting agent, it is preferable to use hydrophobic silica fine particles and hydrophobic titanium oxide fine particles in combination. In particular, when stirring and mixing are performed using particles having an average particle size of 5 × 10-2 μm or less, the electrostatic force and van der Waals force with the toner are remarkably improved. Even when stirring and mixing inside the developing device is performed, a fluidity-imparting agent is not detached from the toner, a good image quality that does not cause fireflies and the like is obtained, and a reduction in residual toner is further achieved. . Titanium oxide fine particles are excellent in environmental stability and image density stability, but have a tendency to deteriorate the charge rise characteristics. Therefore, if the amount of titanium oxide fine particles added is larger than the amount of silica fine particles added, this side effect is affected. It can be considered large. However, when the added amount of the hydrophobic silica fine particles and the hydrophobic titanium oxide fine particles is in the range of 0.3 to 1.5 wt%, the charge rising characteristics are not greatly impaired, and the desired charge rising characteristics can be obtained, that is, repeated copying. Stable image quality can be obtained even if

(Toner production method)
Next, a toner manufacturing method will be described. Here, although a preferable manufacturing method is shown, it is not limited to this.

(1) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent. The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, Methyl isobutyl ketone and the like can be used alone or in combination of two or more. In particular, aromatic solvents such as toluene and xylene and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferable. The usage-amount of an organic solvent is 0-300 weight part normally with respect to 100 weight part of polyester prepolymers, Preferably it is 0-100 weight part, More preferably, it is 25-70 weight part.

(2) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles. The aqueous medium may be water alone or an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (methyl cellosolve, etc.), lower ketones (acetone, methyl ethyl ketone, etc.). It may be included. The amount of the aqueous medium used relative to 100 parts by weight of the toner material liquid is usually 50 to 2000 parts by weight, preferably 100 to 1000 parts by weight. If the amount is less than 50 parts by weight, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter cannot be obtained. If it exceeds 2000 parts by weight, it is not economical.

Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
As surfactants, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, phosphate esters, alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, Quaternary ammonium salt type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, benzethonium chloride, fatty acid amide derivatives, polyhydric alcohols Nonionic surfactants such as derivatives, for example, amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine and N-alkyl-N, N-dimethylammonium betaine And the like. Further, by using a surfactant having a fluoroalkyl group, the effect can be obtained in a very small amount. Preferred anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms and metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6-C11 ) Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carvone Acids and metal salts, perfluoroalkylcarboxylic acids (C7 to C13) and metal salts thereof, perfluoroalkyl (C4 to C12) sulfonic acids and metal salts thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- ( 2-Hydroxyethyl) Perful Olooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. Can be mentioned. Product names include Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS-101. DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos). Moreover, as the cationic surfactant, aliphatic quaternary ammonium such as aliphatic primary, secondary or secondary amic acid, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt which has a right fluoroalkyl group is used. Salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, trade names include Surflon S-121 (Asahi Glass Co., Ltd.), Florard FC-135 (Sumitomo 3M Co., Ltd.), Unidyne DS-202 (Daikin Industries) Smoke), Megafac F-150, F-824 (Dainippon Ink Co., Ltd.), Xtop EF-132 (Tochem Products), Footage F-300 (Neos), and the like.

  The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10 to 90%. For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Techno Examples include polymer SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.). In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the above resin fine particles and inorganic compound dispersant, the dispersed droplets may be stabilized by a polymer protective colloid. For example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride and other (meth) acrylic monomers containing hydroxyl groups Bodies such as acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ-hydroxy Propyl, acrylic acid-3-chloro-2-hydroxypropyl, methacrylic acid-3-chloro-2-hydroxypropyl, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Luric acid esters, N-methylol acrylamide, N-methylol methacrylamide, etc., vinyl alcohol or ethers with vinyl alcohol, such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, or compounds containing vinyl alcohol and a carboxyl group Esters such as vinyl acetate, vinyl propionate, vinyl butyrate, acrylamide, methacrylamide, diacetone acrylamide or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride, vinyl pyridine, vinyl pyrrolidone, vinyl Nitrogen compounds such as imidazole and ethyleneimine, or homopolymers or copolymers such as those having a heterocyclic ring thereof, polyoxyethylene, poly Xoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylenes such as ethylene nonylphenyl ester, celluloses such as methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose can be used.

  The dispersion method is not particularly limited, and known equipment such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 to 20 μm. When a high-speed shearing disperser is used, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 5000 to 20000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 to 5 minutes. The temperature during dispersion is usually 0 to 150 ° C. (under pressure), preferably 40 to 98 ° C.

(3) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group. This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity between the isocyanate group structure of the polyester prepolymer (A) and the amines (B), but is usually 10 minutes to 40 hours, preferably 2 to 24 hours. The reaction temperature is generally 0 to 150 ° C, preferably 40 to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

(4) After completion of the reaction, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . Further, when an acid such as calcium phosphate salt or an alkali-soluble material is used as the dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as dissolving the calcium phosphate salt with an acid such as hydrochloric acid and washing with water. Remove. It can also be removed by operations such as enzymatic degradation.

(5) A charge control agent is injected into the toner base particles obtained above, and then inorganic fine particles such as silica fine particles and titanium oxide fine particles are externally added to obtain a toner. The injection of the charge control agent and the external addition of the inorganic fine particles are performed by a known method using a mixer or the like. Thereby, a toner having a small particle size and a sharp particle size distribution can be easily obtained. Furthermore, by giving strong agitation in the process of removing the organic solvent, the shape between the true spherical shape and the rugby ball shape can be controlled, and the surface morphology is also controlled between the smooth shape and the umeboshi shape. be able to.

  Moreover, as a magnetic carrier of this embodiment, a thing with a weight average particle diameter of 20 micrometers or more and 65 micrometers or less can be used. When the weight average particle size is less than 20 μm, the uniformity of the particles is lowered and carrier adhesion is likely to occur. On the other hand, when the weight average particle diameter exceeds 65 μm, the reproducibility of the image details is lowered and it is difficult to obtain a fine image. In addition, the weight average particle diameter of a carrier can be measured by the range setting of 0.7 micrometer or more and 125 micrometers or less using the SRA type of a micro track particle size analyzer (made by Nikkiso Co., Ltd.). At this time, methanol is used as the solvent of the dispersion, and the refractive index is set to 1.33 and the refractive indexes of the carrier and the core material are set to 2.42.

Further, the magnetic carrier of the present embodiment has a magnetization intensity of 40 [A · m ² / kg] or more and 90 [A · m] in a magnetic field of 1 × 10 ⁶ / 4π [A / m] (1 k [Oe]). ² / kg] or less. As a result, the holding force between the carrier particles is properly maintained, so that the toner is easily dispersed in the magnetic carrier or the developer. When the strength of magnetization in a 1 × 10 ⁶ / 4π [A / m] magnetic field is less than 40 [A · m ² / kg], carrier adhesion tends to occur. On the other hand, when the intensity of magnetization in a magnetic field of 1 × 10 ⁶ / 4π [A / m] exceeds 90 [A · m ² / kg], the rising of the developer formed during development (magnetic brush) It becomes hard, the reproducibility of image details is reduced, and it is difficult to obtain a fine image.
The strength of magnetization can be measured as follows. Using a BH tracer BHU-60 (manufactured by Riken Denshi Co., Ltd.), a cylindrical cell (inner diameter 7 mm, height 10 mm) is packed with 1.0 g of carrier and set in the apparatus. After gradually increasing the magnetic field to 3 × 10 ⁶ / 4π [A / m] (3 k [Oe]), and then gradually decreasing it to 0 [A / m], the opposite magnetic field was applied. Gradually increase to 3 × 10 ⁶ / 4π [A / m] (3 k [Oe]). Further, after gradually reducing the magnetic field to 0 [A / m], the magnetic field is applied in the same direction as the first. In this way, the BH curve is shown, and the intensity of magnetization in a magnetic field of 1 × 10 ⁶ / 4π [A / m] (1 k [Oe]) is calculated from the figure.

  Further, the magnetic carrier of the present embodiment has a resin coat film on the magnetic core material, and the resin coat film is a resin component obtained by crosslinking a thermoplastic resin such as acrylic and a melamine resin. In which a charge adjusting agent is contained. By using a magnetic carrier, it is possible to obtain a good balance between the effect of absorbing impact and suppressing scraping and holding large particles with a strong adhesive force, and the effect of preventing impact on the coating film and cleaning spent materials. . Therefore, it is possible to prevent the long life of the magnetic carrier, that is, film scraping and spent.

Next, the configuration and operation of the developing device, which is a characteristic part of the present invention, will be described.
FIG. 5 is a perspective view showing the appearance of the developing device.
FIG. 6 is a perspective view of a state in which the upper casing is removed so that the inside of the developer accommodating portion of the developing device can be visually recognized.
FIG. 7 is an explanatory diagram showing the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developing sleeve 141 with a two-dot chain line, along with the schematic configuration of the yellow developing device 14Y in the present embodiment.
The magnet roller 147 of the developing device in the present embodiment is a cylindrical member formed by mixing magnetic powder in a resin and magnetizing the peripheral surface to form a plurality of magnetic poles. The diameter of the magnet roller 147 of this embodiment is 18 mm. In the present embodiment, the magnetic poles formed on the magnet roller 147 are developed in order from the developing pole S1 facing the photosensitive drum 12Y in the counterclockwise direction in the drawing (the developer conveying direction by the developing sleeve 141) in order. "S1 pole"), transport poles N1 and S2 (hereinafter referred to as "N1 pole" and "S2 pole", respectively), out-of-agent upstream pole N2 (hereinafter referred to as "N2 pole"), out-of-agent / pumping, This is the regulation pole N3 (hereinafter referred to as “N3 pole”).

  The magnet roller 147 of the present embodiment is integrally formed as a whole, but a magnet member separately formed for each magnetic pole may be disposed around the shaft. As the integrally molded magnet roller 147 as in this embodiment, it is desirable that magnetic powder is dispersed in a resin such as ethylene ethyl acrylate or nylon (registered trademark). The magnetic powder is preferably a rare earth magnet such as strontium ferrite, NdFeB, or SmFeN.

On the other hand, the developing sleeve 141 is a non-magnetic hollow body, and its material is preferably aluminum or stainless steel in view of processability, cost, and durability.
More preferably, a large number of elliptical dents may be randomly provided on the outer peripheral surface of the developing sleeve 141 by, for example, forming a lot of random elliptical dents on the outer peripheral surface of the developing sleeve 141. According to this configuration, the surface of the developing sleeve 141 has a rough pit, so that the situation in which the developer slips without being able to follow the rotation of the developing sleeve 141 can be suppressed. In addition to forming thick spikes with roots, it is difficult for the dents to wear, so a stable and good image without image unevenness can be obtained over a long period of time. Such a dent is preferably formed by causing a medium made of a relatively large cut wire (a metal wire cut into a short length) to collide with the surface of the developing sleeve, as in a conventional blasting method. .
In order to facilitate the conveyance of the developer, it is generally performed to form grooves or irregular irregularities (sand blast, bead blast, etc.) on the surface of the developing sleeve. In particular, in a color image forming apparatus, a developing sleeve having a concavo-convex surface formed by blasting the surface has become the mainstream because of its superior image quality. Such roughing processing such as grooving and blasting is performed in order to prevent a decrease in image density caused by the developer slipping and stagnation on the surface of the developing sleeve rotating at high speed.

  By the developing casing 144, a developer accommodating portion is formed inside the developing device 14Y. The developer accommodating portion is divided into a supply chamber 149A that is positioned below the developing sleeve 141 and extends in the developing sleeve axial direction, and a stirring chamber 149B that is adjacent to the supplying chamber 149A and extends in the developing sleeve axial direction. Yes. Conveying screws 142 and 143 are provided in the supply chamber 149A and the stirring chamber 149B, respectively. The developer transported to the downstream end (back side in the figure) of the supply chamber 149A by the transport screw 143 is transferred to the stirring chamber 149, and the downstream end (front side in the figure) of the stirring chamber 149B by the transport screw 142 in the stirring chamber. It is conveyed toward. The developer conveyed to the downstream end of the stirring chamber 149B is transferred to the supply chamber 149A and is conveyed toward the downstream end of the supply chamber 149A by the conveyance screw 143 in the supply chamber. As described above, the developer is circulated and conveyed in the developer accommodating portion. Replenishment toner for replenishing the amount of toner consumed by development is supplied from the toner replenishment port 145 to the developer in the stirring chamber 149B. The developer in the supply chamber 149A is pumped onto the developing sleeve 141 by the magnetic force of the magnet roller 147 (magnetic force due to the N3 pole) during the conveyance. After that, the developer pumped up on the developing sleeve 141 is regulated by the doctor blade 146, passes through the developing region facing the photosensitive drum 12Y, and returns to the developer containing portion again.

  In the present embodiment, the developer pumped up from the supply chamber 149A by the magnetic force of the N3 pole and adsorbed on the developing sleeve 141 is conveyed counterclockwise in the drawing as the developing sleeve 141 rotates. The developer controlled to a predetermined amount by the doctor blade 146 is spiked by the magnetic force generated by the S1 pole in the development area, and the toner is transferred from the developer spiked by the developing electric field to the electrostatic latent image on the surface of the photosensitive drum 12Y. To perform development processing. The developer after development is conveyed along with the rotation of the developing sleeve 141 while being held on the developing sleeve 141 by the magnetic force of N1 pole → S2 pole → N2 pole. After that, under the action of the repulsive magnetic force (peeling force) and the centrifugal force generated between the N2 pole and the N3 pole, it is detached from the developing sleeve 141 (separated from the agent) and falls into the supply chamber 149A in the developer accommodating portion. .

Note that the magnetic force is calculated by the following formula.
Fr = G × (Hr × (∂Hr / ∂r) + Hr × (∂Hθ / ∂r))
Fθ = G × (1 / r × Hr × (∂Hr / ∂θ) + 1 / r × (Hr × ∂Hθ / ∂θ))
Here, “Fr” represents a normal direction component of the magnetic development sleeve surface, “Fθ” represents a magnetic sleeve surface tangential direction component (hereinafter referred to as “normal magnetic force”), and “Hr” represents magnetic flux. The developing sleeve surface normal direction component (hereinafter referred to as “tangential magnetic force”) of density is shown, and “Hθ” shows the developing sleeve surface tangential component of magnetic flux density. “R” is a calculated radius, and “G” is a constant (7.8 × 10 ⁻¹⁵ ).
In the following description, when the normal direction magnetic force Fr shows a positive value, the magnetic carrier acts in a direction away from the developing sleeve 141, and when the normal direction magnetic force Fr shows a negative value, the magnetic carrier It is assumed that the magnetic force acts in the direction in which the toner is attracted to the developing sleeve 141.
In the following description, the terms “upstream” and “downstream” simply refer to “upstream” and “downstream” in the developer transport direction by the developing sleeve 141.

  In the present embodiment, as shown in FIG. 7, the N3 pole that has the same polarity as the N2 pole and is adjacent to the N2 pole is disposed in the vicinity of the doctor blade 146. Therefore, there is no magnetic field inflection point on the developing sleeve until the developer pumped on the developing sleeve 141 is restricted by the doctor blade 146. Therefore, the developer stress on the upstream side of the doctor blade 146 can be reduced as compared with the conventional apparatus shown in FIG. 28 in which such an inflection point exists.

  In addition, in this embodiment, the developer separating region P defined on the developing sleeve 141, that is, the peeling force toward the developer away from the developing sleeve 141 is applied to the developer on the developing sleeve 141 by the magnetic force of the N2 pole and the N3 pole. The region on the developing sleeve that acts is configured not to contact the developer in the supply chamber 149A. Specifically, the developing sleeve 141 is moved upward as compared with the conventional apparatus shown in FIG. 29 so that the agent separation area P on the developing sleeve 141 does not contact the developer in the supply chamber 149A in the driving state. I have to. Therefore, in the agent separation region P, even if the developer remains on the developing sleeve 141, a situation in which the developer is scraped off by the developer in the supply chamber 149A does not occur. Therefore, the developer stress can be further reduced as compared with the conventional apparatus shown in FIG. 29 in which the agent separation region P is configured to contact the developer in the supply chamber 149A. In addition, in the conventional apparatus shown in FIG. 29, as shown in FIG. 30 (b), the developer that is in a solid state due to the magnetic force of the N3 pole is developed by the shearing force of the conveying screw 143 or the conveying screw 143. Since it receives a shearing force from the developer conveyed in the sleeve axial direction, this causes a great stress on the developer. On the other hand, in the present embodiment, as shown in FIG. 30A, the developer that is hardened and hardened by the magnetic force of the N3 pole hardly receives such a shearing force. Is small.

  On the other hand, since the developer in the supply chamber 149A that has been responsible for the scraping function in the conventional apparatus shown in FIG. 29 does not contact the agent separation region P in this embodiment, If the developer has not been sufficiently peeled off from the developing sleeve 141, revolving occurs. 29, the developer in the supply chamber 149A that has been in contact with the agent separation region P in the conventional apparatus shown in FIG. 29 is captured by the magnetic force of the N3 pole in the developer separated from the developing sleeve 141 in the agent separation region P. The developer pumping region (the developer pumping region adjacent to the downstream side of the agent separation region P, where the pumping force is applied by the magnetic force of the N3 pole) and the developer sucked toward this region are reattached. Although it functions also as a wall for preventing, in this embodiment, there is no developer that becomes such a wall. Therefore, in this embodiment, if the developer peeled off in the agent separation region P cannot be separated to a location sufficiently away from the developer pumping region, re-adhesion occurs.

  Therefore, in the present embodiment, the normal direction magnetic flux density Hr in the agent separation region P defined on the developing sleeve 141 has the same N pole direction (positive) as the N2 pole and the N3 pole over the entire region of the agent separation region P. Value) and not having a local maximum. As a result, as will be described later, the developer can efficiently act on the developer adhering on the developing sleeve 141 in the agent separation region P, and the developer can be expected to have a scraping effect on the agent separation region P. Even if the developer that becomes the re-adhesion wall is not in contact, it is possible to effectively suppress the occurrence of follow-up and re-adhesion.

FIG. 8 is a graph showing the normal direction magnetic flux density (thin line) on the surface of the developing sleeve 141 and the normal direction magnetic force (thick line) on the surface of the developing sleeve 141 in the periphery of the agent separation region P of the present embodiment. It is.
FIG. 9 is a graph showing the normal direction magnetic flux density (thin line) on the surface of the developing sleeve 141 and the normal direction magnetic force (thick line) on the surface of the developing sleeve 141 around the agent separation region P of the comparison device. is there.
In this graph, the region where the normal direction magnetic force (thick line) takes a positive value is the agent separation region P.
Note that the angle shown on the horizontal axis of these graphs is 0 ° at the point on the developing sleeve 141 where the normal direction magnetic flux density by the S1 pole is maximum, and the developing sleeve rotation direction (counterclockwise direction in the figure) is positive. The point on the developing sleeve 141 is expressed as an angle.

  The comparison device simply moves the developing sleeve 141 upward so that the agent separation region P on the developing sleeve 141 does not contact the developer in the supply chamber 149A in the driving state. As shown in FIG. 9, the comparison device is configured such that the normal direction magnetic force Fr, which is a peeling force in the agent separation region P, has two local maximum points. Then, the developer is removed from the developing sleeve 141 in the agent separation region P by the amount that the portion of the minimum point existing between these maximum points is greatly depressed (about 25% of the maximum normal direction magnetic force in the agent separation region P). Loss when peeling was large. And, according to the study by the present inventors, the reason why the minimum point portion of the normal direction magnetic force Fr is greatly reduced is as follows. In other words, in the comparison device, the N2 pole and the N3 pole are used to prevent a reversal point between the N2 pole and the N3 pole from being generated so that the normal direction magnetic flux density is reversed to generate an attractive force that attracts the developer. A weak N pole was present between the two. As a result, the normal direction magnetic flux density Hr in the agent separation region P defined on the developing sleeve 141 is the same N-pole direction (positive value) as the N2 and N3 poles throughout the agent separation region P. In the agent separation region P, a suction force that attracts the developer to the developing sleeve does not occur. However, since such a weak N pole was present, as shown in FIG. 9, a slight maximum point was generated at a portion corresponding to the weak N pole. It has been found that this slight maximum point is a major factor that greatly reduces the minimum point portion of the normal direction magnetic force Fr.

Therefore, in this embodiment, as shown in FIG. 8, the normal direction magnetic flux density Hr in the agent separation region P defined on the developing sleeve 141 is the same as the N2 pole and the N3 pole over the entire region of the agent separation region P. It is configured so as not to have a local maximum point while being in the direction of the N pole (positive value).
Hereinafter, an example of a manufacturing method of the magnet roller 147 having such a normal direction magnetic flux density distribution will be described.

FIG. 10 is an explanatory diagram of a magnetizing process when manufacturing the magnet roller 147 of the present embodiment.
FIG. 11 is an explanatory diagram of a magnetizing process when manufacturing the magnet roller 447 of the comparison device.
Each of the magnet rollers 147 and 447 performs a magnetizing process on a cylindrical member formed by mixing magnetic powder in a resin, with the magnetizing yokes 181 to 186 and 481 to 486 facing the peripheral surface, and S1 A pole, N1 pole, S2 pole, N2 pole, and N3 pole are formed. The magnetizing yokes 181 to 186 and 481 to 486 corresponding to the magnetic poles have different magnetic forces, shape dimensions, and the like depending on the width of the magnetic pole to be formed and the strength of the magnetic field. As shown in FIG. 11, in the comparison device, the magnetizing yoke 486 for forming a weak N pole between the N2 pole and the N3 pole has a facing surface portion facing the peripheral surface of the magnet roller 447 other than the other. Since it is flat like the magnetizing yoke, its central portion is most strongly magnetized. Therefore, the normal direction magnetic flux density Hr in the agent separation region P defined on the developing sleeve 141 is surely the same N-pole direction (positive value) as the N2 and N3 poles throughout the agent separation region P. When trying to be magnetized in such a way, there is inevitably a maximum point as shown in FIGS.

  Therefore, in this embodiment, a weak N pole is formed between the N2 pole and the N3 pole by using a magnetized yoke 186 as shown in FIG. Specifically, a magnetizing yoke 186 having a shape in which the central portion of the facing surface portion facing the peripheral surface of the magnet roller 147 is farther from the peripheral surface of the magnet roller 147 than the other portions is used. To do. As a result, the magnetization of the central portion can be weakened. Therefore, the magnet is magnetized so as to have the same N-pole direction (positive value) as the N2-pole and N3-pole throughout the agent separation region P. FIG. Alternatively, as shown in FIG. 10, it is possible not to have a local maximum point.

The method of manufacturing the magnet roller 147 illustrated here is an example, and the same N-pole direction (positive value) as the N2-pole and N3-pole is provided over the entire area of the agent separation region P, and has no maximum point. Other manufacturing methods may be adopted as long as the manufacturing method can be used.
Further, in cooperation with not only the magnet roller 147 but also the surrounding magnetic members, the N-pole direction (positive value) is the same as the N2-pole and N3-pole over the entire agent separation region P, and the maximum point Such a configuration can also be adopted if it is possible not to have.

  According to the present embodiment, since the normal direction magnetic flux density Hr in the agent separation region P does not have a maximum point as shown in FIG. 8, the developer is separated from the developing sleeve 141 in the agent separation region P. It is possible to reduce the drop of the minimum point portion of the normal magnetic force (peeling force) Fr having a positive value that becomes a loss. Specifically, the drop of the normal direction magnetic force (peeling force) Fr at the minimum point can be suppressed to about 90% of the maximum value. If the drop can be suppressed so that the magnitude of the normal direction magnetic force (peeling force) Fr at the minimum point is 50% or more of the maximum value, a developer or a developer that can be expected to have a scraping effect in the agent separation region P can be used. Even if the developer that becomes the adhesion wall is not in contact, it is possible to effectively suppress the occurrence of accompanying and redeposition, and it is possible to effectively prevent deterioration of image quality due to the accompanying and redeposition.

  In addition, as shown in FIG. 12, you may comprise so that the normal direction magnetic force (peeling force) Fr in the agent separation area | region P may have a single maximum point. Specifically, the magnetization process of each magnetic pole of the magnet roller 147 is adjusted so as to have such a configuration. According to this configuration, there is no minimum point of the normal direction magnetic force (peeling force) Fr as shown in FIG. 8, and there is no situation in which the normal direction magnetic force Fr temporarily falls in the agent separation region P. Loss when the developer is peeled from the developing sleeve 141 in the agent separation region P can be minimized. Therefore, it is possible to effectively prevent image quality deterioration due to rotation and reattachment.

  Further, as shown in FIG. 13, with respect to the developer conveying direction by the developing sleeve 141, the normal point magnetic flux density Hr1 by the N2 pole becomes the maximum on the developing sleeve, and the normal direction magnetic flux density by the N3 pole. A point Hr3 indicating the minimum value of the normal direction magnetic flux density Hr on the developing sleeve is an intermediate point between the first point Hr1 and the second point Hr2 between the second point Hr2 where Hr is the maximum on the developing sleeve. It may be configured to be located on the second point Hr2 side. As a result, the agent separation region P approaches the N3 pole, so that the developer that has detached from the developing sleeve 141 is less likely to be reattached.

  It has been found that the above-described problem of reattachment is significant when the surface moving speed of the developing sleeve 141 is 350 [mm / sec] or more. Therefore, the present invention is very useful when the surface moving speed of the developing sleeve 141 is 350 [mm / sec] or more.

  Here, in this embodiment, as shown in FIG. 7, a magnet 149 as a repulsive magnetic field generating member is arranged. As shown in FIG. 14, the position of the magnet 149 in the developer conveyance direction by the developing sleeve 141 is N3 on the developing sleeve from the normal line H1 of the maximum normal direction magnetic flux density by the N2 pole on the developing sleeve. It is between the normal H2 of the maximum point of the normal direction magnetic flux density by a pole. Further, as shown in FIG. 15, the position of the magnet 149 in the axial direction of the developing sleeve 141 is on the outer side in the axial direction of the developing sleeve 141 with respect to the area facing the magnet roller 147. And this magnet 149 is arrange | positioned so that the magnetic pole surface of the same pole (N pole) as N2 pole and N3 pole may go to the agent separation area | region P. FIG.

In the case where such a magnet 149 is not provided, the developer revolving as described above occurs in the end region in the axial direction of the developing sleeve in the region facing the magnet roller 147 on the outer peripheral surface of the developing sleeve 141. This is because, in the agent separation region P, the magnetic force lines generated in the developing sleeve axial direction end region in the region facing the magnet roller 147 are directed outward in the developing sleeve axial direction. Since the component toward the outside in the axial direction of the developing sleeve is large and the peeling force cannot be effectively applied to the developer, the rotation of the developer occurs.
In the present embodiment, by providing the magnet 149 described above, the direction of the magnetic force lines in the end region in the axial direction of the developing sleeve in the opposing region of the magnet roller 147 in the agent separation region P on the developing sleeve is changed to the developing sleeve. It is possible to approach the direction orthogonal to the axial direction. As a result, the peeling force in this end region is improved, so that the peeling force can be effectively applied to the developer also in this end region, and the developer can be efficiently separated from the outer peripheral surface of the developing sleeve 141. As a result, the rotation of the developer can be effectively suppressed even in this end region.

The magnetic pole surface of the N pole of the magnet 149 may be disposed so that the position in the axial direction of the developing sleeve extends over the developing sleeve axial end of the magnet roller 147. However, in this case, of the magnetic pole surface, the magnetic pole surface portion disposed on the outer side in the developing sleeve axial direction of the developing roller axial direction of the magnet roller 147 develops more than the developing sleeve axial end of the magnetic roller 147. It is configured to generate a stronger magnetic field than the magnetic pole surface portion (the magnetic pole surface portion facing the opposing region of the magnet roller 147) arranged on the inner side in the sleeve axial direction. For example, when the magnetic pole surface of the N pole of the magnet 149 is uniform, the magnet 149 is arranged such that the area of the magnetic pole surface portion arranged outside is larger than the area of the magnetic pole surface portion arranged inside. With such a configuration, even if the N-pole magnetic pole surface of the magnet 149 is arranged so as to straddle the developing sleeve axial end portion of the magnet roller 147, the magnetic field lines in the developing sleeve axial end region of the magnet roller 147 are arranged. Can be obtained in such a manner that the direction of the ink is close to a direction orthogonal to the axial direction of the developing sleeve.
However, as in the present embodiment, the direction in which the magnetic lines of force are oriented with respect to the axial direction of the developing sleeve is configured such that the N-pole magnetic pole surface of the magnet 149 is not disposed at a location facing the opposing region of the magnet roller 147 Therefore, it is possible to effectively suppress the rotation of the developer.

  Further, in this embodiment, as shown in FIG. 15, the position in the developer transport direction by the developing sleeve 141 is on the developing sleeve from the normal line H1 of the maximum normal direction magnetic flux density by the N2 pole on the developing sleeve. The position in the axial direction of the developing sleeve 141 is outside the effective developing area facing the image forming area on the photosensitive drum. A seal member 148 for sealing between the outer peripheral surface of the developing sleeve 141 and the casing 144 of the developing device 14Y is provided at a certain location. In this embodiment, the entire magnetic pole surface of the N pole of the magnet 149 is disposed at a position where the position in the developing sleeve axial direction is outside the inner end of the sealing member 148 in the developing sleeve axial direction. With such a configuration, even when the magnet 149 is disposed, it is possible to suppress the developer in the developer accommodating portion from being retained due to the magnetic force of the magnet 149.

  In this embodiment, the N pole magnetic pole surface of the magnet 149 is disposed so as to face the outer peripheral surface of the developing sleeve 141. However, the magnetic pole surface does not necessarily face the outer peripheral surface of the developing sleeve. Good. Therefore, for example, the N pole surface of the magnet 149 may be disposed at a position where the position in the axial direction of the developing sleeve is outside the axial end of the developing sleeve 141. As a specific example, for example, the magnet 149 is disposed on the outer surface of the seal member 148 in the developing sleeve axial direction so that the N pole magnetic pole surface faces the inner side in the developing sleeve axial direction. Even in this case, the effect of bringing the direction of the magnetic lines of force in the developing sleeve axial end region of the magnet roller 147 closer to the direction orthogonal to the developing sleeve axial direction can be obtained.

  In the present embodiment, the development distance carried on the outer peripheral surface portion of the developing sleeve is such that the shortest distance X (see FIG. 14) between the N-pole magnetic pole surface of the magnet 149 and the outer peripheral surface of the developing sleeve 141 is the shortest distance. It is comprised so that it may become larger than the height of an agent. With such a configuration, the developer on the developing sleeve is not kicked by the magnetic force of the magnet 149 when the developing sleeve 141 is rotating, and a targeted effect such as agent separation can be obtained without any adverse effects.

Next, the doctor auxiliary member 146b as a magnetic member fixed to the upstream side surface of the doctor blade 146, which is a characteristic part of the present invention, will be described.
In the developing device of this embodiment, since the inflection point Q does not exist in the upstream region of the restricting position as in the developing device as shown in FIG. 29, the developer does not stay much in the upstream region of the restricting position. As compared with the developing device as described above, the stress of the developer is reduced. Note that the developing device of the present embodiment is configured such that the situation in which the developer on the agent separation region P is not scraped off by the developer in the supply chamber 149A does not occur, so the agent separation region P is in the supply chamber 149A. The developer stress can be further reduced as compared with the conventional apparatus shown in FIG. 29 configured to come into contact with the developer inside.
In the developing device of this embodiment, since the developer does not stay much in the upstream region of the restriction position, as described above, the toner density deviation of the developer due to the developer staying in the upstream area of the restriction position is equalized. Almost no effect is obtained. Therefore, when the developer after development does not separate from the development sleeve 141 and is rotated, or after development, the developer that has fallen onto another developer in the first storage chamber (supply chamber) 349A is removed. When pumped immediately, the developer portion with a low toner concentration and the developer portion with a high toner concentration coexist and pass through the regulation position and are conveyed to the development region, causing image density unevenness. Cheap.

FIG. 16 is an explanatory diagram showing a shape of the doctor blade 146 in this embodiment when viewed from the developing sleeve axial direction.
FIG. 17A is an explanatory view showing the behavior of the developer upstream of the doctor blade in the developing device of this embodiment, and FIG. 17B is the behavior of the developer upstream of the doctor blade in the conventional developing device. It is explanatory drawing which shows.
In the present embodiment, the doctor auxiliary member 146b is obtained by bending a flat thin plate so that the cross-sectional shape orthogonal to the developing sleeve axial direction is substantially L-shaped. One plate surface portion (hereinafter referred to as “magnetic pole facing surface”) 146b1 obtained by bending is disposed so as to face the N3 pole over the effective developing width, that is, over the entire longitudinal direction of the image forming area on the developing sleeve. The other plate surface portion 146b2 is a joint surface of the doctor blade to the doctor base 146a. The joint surface 146b2 is joined to the upstream side surface of the doctor base 146a by a known method. Thereby, the doctor auxiliary member 146b is fixed to the doctor base 146a. In the present embodiment, the magnetic pole facing surface 146b1 disposed so as to face the N3 pole over the effective development width has a surface direction that is a tangential direction in a region on the developing sleeve 141 where the normal direction magnetic flux density by the N3 pole exists. It arrange | positions so that it may become substantially parallel. In the present embodiment, the magnetic pole facing surface 146b1 has a normal direction at the center thereof and a normal direction at a point on the outer peripheral surface of the developing sleeve 141 having the shortest distance from the magnetic pole facing surface 146b1. They are arranged in parallel.

In the conventional developing device in which the sheet surface of the magnetic sheet 546b, which is a thin flat magnetic body, is joined to the upstream side surface of the doctor base 146a of the doctor blade so that the end surface of the magnetic sheet 546b faces the N3 pole. As shown in FIG. 17B, the developer in the upstream region of the doctor blade is raised by the magnetic force of the N3 pole. Therefore, the developer in the upstream region of the doctor blade is in a sparse state and is restrained by a strong magnetic force on the outer peripheral surface of the developing sleeve. Therefore, almost all of the developer that has entered the upstream region of the doctor blade moves so as to slide as it follows the surface movement of the developing sleeve 141 and passes through the regulation position. Therefore, when the developer having a remarkable toner density deviation is conveyed to the upstream region of the doctor blade, it passes through the regulation position so as to slide as it is, and image density unevenness occurs.
On the other hand, in the present embodiment, since the magnetic pole facing surface 146b1 is disposed so as to face the N3 pole, as shown in FIG. 17 (a), it is wide between the magnetic pole facing surface 146b1 and the N3 pole. A magnetic field concentration region is formed. That is, the length of the magnetic field concentration region (the length in the developer transport direction by the developing sleeve 141) between the magnetic pole facing surface 146b1 and the N3 pole in the upstream region of the doctor blade is long. Therefore, in this embodiment, the developer that has entered the magnetic field concentration region in the upstream region of the doctor blade collides with the developer already constrained in the magnetic field concentration region, or is restricted by the magnetic field in the magnetic field concentration region. Or move in the magnetic field concentration region while being prevented from proceeding. As a result, even if the developer having a remarkable toner density deviation is conveyed to the magnetic field concentration area, the toner density deviation is leveled after passing through the magnetic field concentration area, and the deviation can be reduced.

  In addition, when the conventional developing device shown in FIG. 17B is also viewed microscopically, a narrow magnetic field concentration region is formed between the end face of the magnetic sheet 546b and the N3 pole. It is presumed that the agent behaves in the same manner as in the magnetic field concentration region in this embodiment. However, in the conventional developing device shown in FIG. 17B, the length of the magnetic field concentration region is too short, and the effect of equalizing the toner density deviation of the developer cannot be effectively obtained, and the effect of reducing the image density unevenness. Can hardly be obtained. On the other hand, if the magnetic sheet 546b is thickened and the length of the magnetic field concentration region between the end face of the magnetic sheet 546b and the N3 pole is set to the same length as in the present embodiment, the magnetic sheet Since 546b becomes too large, the magnetic field on the outer peripheral surface of the developing sleeve is greatly disturbed, and adverse effects such as poor developer conveyance and poor pumping of the developer by the developing sleeve 141 are impractical.

  In the present embodiment, the upstream end of the magnetic pole facing surface 146b1 is a point where the normal direction magnetic flux density by the N3 pole becomes the maximum on the developing sleeve 141, as shown in FIG. The doctor auxiliary member 146b is arranged so as to be upstream from the normal line. As a result, the magnetic field concentration region can be formed with the strongest magnetic force, so that a higher effect than leveling out the toner density deviation of the developer can be obtained. However, if the upstream end portion of the magnetic pole facing surface 146b1 extends too far upstream, it may cause a pumping failure, and the upstream end portion of the magnetic pole facing surface 146b1 is necessarily limited. Become.

  Further, in this embodiment, as shown in FIGS. 7 and 17A, the upstream end portion of the restriction surface of the doctor blade 146 is a point where the normal direction magnetic flux density by the N3 pole becomes the maximum on the developing sleeve. The doctor blade 146 is arranged so as to be downstream from the normal line. As a result, the developer can be cut off at the portion where the magnetic brush is densely laid, so that a stable amount of the developer deteriorated with time can be supplied to the development region. This will be described in detail below.

  FIG. 18 is a graph in which the horizontal axis indicates the point at which the normal direction magnetic flux density due to the N3 pole is maximum on the developing sleeve (N3 pole peak point) as an angle, and the vertical axis indicates the pumping change rate. is there. The angle of the horizontal axis indicates that the restriction position of the doctor blade 146 is 0 °, the positive direction indicates that the N3 pole peak point is located downstream of the restriction position, and the negative direction indicates that the N3 pole peak point is the restriction position. It shows that it is located upstream. In addition, the change rate of pumping on the vertical axis indicates the ratio of pumping amount of deteriorated developer to pumping amount of new developer (the amount passing through the regulation position, that is, the amount transported to the developing area). The amount of drop from (new developer-deteriorated developer / new developer) is expressed as a percentage. When the pumping change rate is zero, the change in the new developer and the deteriorated developer is small, and the change in the pumping amount increases as the percentage increases.

As shown in FIG. 18, it can be seen that as the N3 pole peak point shifts to the upstream side with respect to the doctor blade 146, the pumping change is smaller. This mechanism can be explained by the tangential magnetic force of the outer peripheral surface of the developing sleeve 141.
FIG. 19 is an explanatory diagram showing a magnetic force distribution in the vicinity of the restriction position of the doctor blade 146. Although the tangential magnetic force is zero at the peak point of the normal magnetic force (N3 pole peak point), the tangential magnetic force is gradually generated as it goes downstream. By utilizing this tangential magnetic force, it becomes possible to stabilize the pumping performance of the developer.
FIG. 20 shows a case where the restriction position of the doctor blade 146 coincides with the N3 pole peak point (arranged at the highest position), and the restriction position of the doctor blade 146 is located at the center between the two magnetic poles in the developer transport direction by the developing sleeve ( It is a graph which shows the result of having measured the pumping amount with respect to a doctor gap about three types of cases, when it is located between the center and its downstream magnetic pole (intermediate arrangement). As can be seen from this graph, the pumping amount increases as the restriction position of the doctor blade 146 is closer to the extreme, so that the doctor gap for obtaining a desired pumping amount is narrower as it is closer to the extreme. For this reason, foreign matters and the like are easily clogged in the doctor gap, and the occurrence of abnormal images increases. On the other hand, the closer the restriction position of the doctor blade 146 is to the maximum, the smaller the pumping amount, so that it becomes difficult to obtain a desired pumping amount. Therefore, the restriction position of the doctor blade 146 is preferably the above intermediate arrangement. More preferably, the restriction position of the doctor blade 146 is arranged at a point on the developing sleeve 141 where the normal magnetic flux density by the N3 pole is 1/3 of the maximum value on the developing sleeve 141.

  In this embodiment, by adopting a configuration in which the magnetic member is fixed to the doctor base 146a of the doctor blade 146 as the doctor auxiliary member 146b, the mutual rigidity is complemented. You may arrange | position in the position spaced apart from the doctor base | substrate 146a of the doctor blade 146. FIG. For example, as shown in FIG. 21, a magnetic member 446 b may be attached to the inner wall of the developing casing 144. Thus, by arranging the magnetic member independently of the doctor blade 146, the distance between the developing sleeve 141 and the magnetic member can be kept constant regardless of the gap between the doctor blade 146 and the developing sleeve 141. Therefore, an effect of stably leveling the toner density deviation of the developer can be obtained.

  Moreover, as a doctor auxiliary member of this embodiment, as shown in FIG. 22, a doctor blade upstream area may become a wedge shape.

[Embodiment 2]
Next, another embodiment in which the present invention is applied to a printer as in the case of the first embodiment (hereinafter, this embodiment is referred to as “second embodiment”) will be described.
Except as described below, the configuration and operation of the present embodiment are the same as those of the first embodiment.

Generally, it is preferable to block the developer from outside air when shipping and transporting the developing device containing a two-component developer containing toner and a magnetic carrier. This is because the performance of the toner component in the developer is likely to deteriorate due to humidity and temperature, and the developer may flow out due to vibration during transportation.
As a method of blocking the developer from the outside air, a developer preset case is conventionally provided above the developer container where the developer agitating and conveying screw is arranged, and the space between the developer container and the developer preset case is shielded. As described above, there is a method in which a sheet-like sealing member is detachably bonded to the inner wall surface of the developing device. According to this method, when the seal member is pulled out of the developing device when the image forming device is installed at the place where the image forming device is used, the adhesive surface of the seal member peels from the inner wall surface of the developing device. As a result, the developer accommodating portion and the developer preset case communicate with each other, the developer in the developer preset case enters the developer accommodating portion, and the developing device can be used.
As another method, a sheet-like sealing member is used to seal the developer in a developer accommodating portion (stirring space) in which the agitating and conveying screw is disposed by shielding between the developing sleeve and the agitating and conveying screw. There is also known a method of adhering to the inner wall surface of the developing device in a peelable manner. According to this method, since it is not necessary to provide a developer preset case, there is an advantage that the developing device can be downsized.

  Here, as an image forming apparatus adopting the latter method, for example, there is one disclosed in JP-A-2002-372862. In view of the difficulty in manufacturing or reusing the seal member on the inner wall surface of the developing device, the image forming apparatus affixes the seal member to the partition frame and attaches the partition frame to the developing sleeve. And a stirring / conveying screw. However, in this image forming apparatus, after the seal member is pulled out of the developing device at the start of use of the developing device, the partition frame remains inside the developing device and does not particularly contribute to image formation. For this reason, there is a problem in that the degree of freedom of layout in the developing device is limited by a member called a partition frame that does not function at all. Further, the end of the partition frame in the direction of the developing sleeve rotation axis prevents the movement of the developer in the developer accommodating portion corresponding to the end region of the developing sleeve, so that the image portion corresponding to the end region in the axial direction of the developing sleeve There is also a problem that adverse effects such as density unevenness are likely to occur. Furthermore, as a method of attaching the sheet member to the partition frame in a peelable manner, for example, a sheet material having a heat-sensitive adhesive layer formed on one side of a laminate film of polyethylene and nylon is used with a partition frame-shaped welding jig. However, there is also a problem in that the structure for attaching the sheet member increases the manufacturing cost.

  In consideration of the above problems, as a method of blocking the developer from the outside air, a member that does not function at all such as a partition frame after use of the developing device does not remain in the developing device, and a seal member is attached. A method that eliminates the need for a process is desired. In the present embodiment, a configuration capable of realizing such a method is employed.

FIG. 23 is an external perspective view of the developing device according to the present embodiment.
FIG. 24 is a perspective view of a state in which the upper casing is removed so that the inside of the developer accommodating portion of the developing device can be visually recognized.
FIG. 25 shows a schematic configuration of the developing device, as viewed from the developing sleeve axial direction.
Before use of the developing device, one end portion of the hermetic seal 150 as a sealing member in the present embodiment is exposed from an opening 144A provided on one end surface of the developing casing 144 in the developing sleeve axial direction. Then, by pulling the end portion along the direction indicated by A in the drawing (axial direction of the developing sleeve) and pulling out the sealing seal 150, the sealing seal 150 can be taken out of the developing device.

  As shown in FIG. 25, when the printer according to this embodiment is shipped or transported, the hermetic seal 150 shields between the developing sleeve 141 and the conveying screws 142 and 143, and the conveying screws 142 and 143 are arranged. The inside of the developer container (stirring space) is sealed. At this time, the developer is accommodated in advance in the developer accommodating portion. However, since the developer is sealed by the hermetic seal 150, the developer does not come into contact with the outside air until the hermetic seal 150 is removed. Problems such as changes in the characteristics of the developer and leakage of the developer do not occur.

  In the present embodiment, the hermetic seal 150 is a plate-like member that is long along the axial direction of the developing sleeve, and is bonded to the inner wall surface of the developing casing 144 with an adhesive or the like as shown in FIG. It is only in contact with the inner wall surface of the developing casing 144. However, in order to maintain the contact state between the hermetic seal 150 and the inner wall surface of the developing casing 144, in this embodiment, the inner wall surface portion of the developing casing 144 indicated by reference numeral 144B and the doctor auxiliary member 146b extend in the axial direction of the developing sleeve. Further, the hermetic seal 150 is sandwiched between the lower casing inner wall surface portion denoted by reference numeral 144C and the upper casing inner wall surface portion denoted by reference numeral 144D. When pulling out the hermetic seal 150 along the axial direction of the developing sleeve, the hermetic seal 150 can be pulled out to the outside of the developing device while causing sliding at these clamping portions.

  According to this embodiment, unnecessary members that do not function at all after the start of use of the developing device do not remain in the developing device, and such members limit the degree of freedom of layout inside the developing device. There is no problem. Further, in the present embodiment, since the hermetic seal 150 is not configured to be adhered by an adhesive or the like, there is an effect that the manufacturing cost can be reduced as compared with the configuration in which the hermetic seal 150 is adhered.

[Embodiment 3]
Next, still another embodiment (hereinafter, this embodiment is referred to as “third embodiment”) in which the present invention is applied to a printer as in the first and second embodiments will be described.
Except as described below, the configuration and operation of the present embodiment are the same as those of the first embodiment.

Further, in the vicinity of the regulation position where the developer is regulated by the doctor blade 146, heat is generated due to friction between the doctor blade 146 and the developer, friction between the surface of the developing sleeve 141 and the developer, friction between the developers, and the like. To do. This increase in the temperature of the developer due to heat causes problems such as generation of toner aggregates in the developer and shortening of the developer life by promoting toner spent on the magnetic carrier due to toner softening. . Further, since the external additive added to the toner is buried in the softened toner and the chances of the magnetic carriers coming into direct contact with each other increases, there arises a problem that the developer is deteriorated by changing the shape of the magnetic carrier. Further, the temperature rise of the toner in the developer also causes toner filming on the surface of the developing sleeve 141. That is, when the temperature of the toner rises at the restriction position, the toner becomes soft and eventually the toner may melt. In this case, the toner melt adheres to the surface of the developing sleeve 141 in the form of a film and causes toner filming. Further, as described above, when toner aggregates are likely to be generated due to a rise in toner temperature, the toner aggregates are sandwiched between the developing sleeve 141 and the doctor blade 146 (doctor gap S), and white toner is displayed on the image. There is also a risk of streaking. In recent years, there has been a tendency to lower the fixing temperature in order to meet the demand for energy saving, but as a result, a toner having a low melting point has been adopted, so it is important to suppress the temperature rise at the regulation position. The degree is increasing.
Therefore, in the third embodiment, instead of the doctor auxiliary member 146b of the first embodiment, the developing sleeve 141 extends in the axial direction (rotating axis direction) of the developing sleeve 141 in order to suppress the temperature rise at the restriction position. A hollow member 646 having a hollow region inside is used.

FIG. 26 is an explanatory diagram showing the shape of the hollow member 646 arranged on the upstream side of the doctor blade 146 in this embodiment when viewed from the axial direction of the developing sleeve and the behavior of the developer on the upstream side of the doctor blade.
The hollow member 646 is processed so that the shape of the cross section orthogonal to the developing sleeve axial direction is substantially square. The magnetic pole facing surface 646b1 of the hollow member 646 is the same as the magnetic pole facing surface 146b1 of the doctor auxiliary member 146b in the above embodiment, and is disposed so as to face the N3 pole over the effective developing width. Therefore, in the third embodiment, similarly to the first embodiment, a wide magnetic field concentration region is formed between the magnetic pole facing surface 646b1 and the N3 pole, and the developer that has entered the magnetic field concentration region in the upstream region of the doctor blade is The developer collides with the developer already constrained in the magnetic field concentration region or is constrained by the magnetic field in the magnetic field concentration region, and moves in the magnetic field concentration region while being prevented from proceeding. As a result, even if the developer having a remarkable toner density deviation is conveyed to the magnetic field concentration area, the toner density deviation is leveled after passing through the magnetic field concentration area, and the deviation can be reduced.

  Here, in this embodiment, a wide magnetic field concentration region is formed in the upstream region of the doctor blade, and the developer that has entered the magnetic field concentration region collides with the developer constrained in the magnetic field concentration region. Therefore, compared with the conventional configuration in which such a wide magnetic field concentration region is not formed, the temperature of the developer is likely to rise in the upstream region of the doctor blade. For this reason, the above-described problems due to the temperature rise are likely to occur, and it is more important to suppress the temperature rise than the conventional configuration.

  Therefore, in the third embodiment, a hollow member 646 formed of the same material as the doctor auxiliary member 146b is used instead of the doctor auxiliary member 146b of the first embodiment. The hollow member 646 is open at both ends in the axial direction of the developing sleeve. Accordingly, an air flow generated in the printer by an exhaust fan or an intake fan (not shown) provided in the printer main body as a cooling means (not shown) generates an air flow in a hollow region in the hollow member 646, and heat of the magnetic pole facing surface 646b1 of the hollow member 646 Are efficiently removed through the air in the hollow region. Therefore, the heat of the developer present in the upstream region of the doctor blade can be efficiently removed through the magnetic pole facing surface 646b1 of the hollow member 646. As a result, the temperature rise of the developer in the upstream region of the doctor blade can be effectively suppressed.

  In the third embodiment, as a cooling means for cooling the hollow member 646 by moving the heat in the hollow region of the hollow member 646 to the outside of the hollow region, an intake fan that takes in the outside air of the printer main body into the printer, Although the example using the exhaust fan which discharges the inside air of the main body to the outside has been described, the present invention is not limited to this. For example, in the vicinity of the opening of the hollow member 646, a blowing unit that sends air directly into the hollow region and a suction unit that sucks air directly from the hollow region may be provided as the cooling unit. Further, a cooling means that circulates the cooling liquid cooled by the cooling device so as to pass through the hollow region of the hollow member 646 may be used. In this case, both ends of the hollow member 646 in the axial direction of the developing sleeve may not be open.

  In addition, as a hollow member of this Embodiment 3, as shown in FIG. 27, you may use what made the outer surface part 746b2 of the hollow member 746b contact the doctor base | substrate 146a of a doctor blade. At this time, the outer surface portion 746b2 of the hollow member 746b may be a bonding surface with respect to the doctor base 146a. This joining surface is joined to the upstream side surface of the doctor base 146a by a known method. Thereby, the hollow member 746b is fixed to the doctor base 146a. As described above, by bringing the outer surface portion 746b2 of the hollow member 746b into contact with the doctor base 146a, the heat of the magnetic pole facing surface 646b1 of the hollow member 646 can be moved from the outer surface portion 746b2 to the doctor base 146a. Therefore, not only the hollow member 646 but also the heat dissipation effect of the doctor base 146a can be obtained. Accordingly, the heat of the developer existing in the upstream region of the doctor blade can be more efficiently removed through the magnetic pole facing surface 646b1 of the hollow member 646, and the temperature increase of the developer in the upstream region of the doctor blade can be more effectively performed. Can be suppressed.

As described above, in the developing devices 14Y, 14C, 14M, and 14K according to the first and second embodiments, the magnetic roller 147 as the magnetic field generating unit is disposed in the developing sleeve 141 that is a non-magnetic hollow body, and the magnetic force of the magnet roller 147 is set. Is provided with a developer carrier for carrying and transporting a two-component developer comprising a magnetic carrier and toner on the outer peripheral surface of the developing sleeve 141, and a supply chamber 149A for accommodating the developer carried on the developing sleeve 141. The developer accommodating portion, conveying screws 142 and 143 as agitating and conveying members that convey the developer along the rotation axis direction of the developing sleeve 141 while stirring the developer, and the layer thickness of the developer carried on the developing sleeve 141 are regulated. And a doctor blade 146 as a developer regulating member for controlling the magnetic force of the magnet roller 147 from within the developer accommodating portion. Ri the developer carried on the developing sleeve 141, the photosensitive drum 12Y after regulated by the doctor blade 146, 12C, 12M, and passed through a 12K opposed to the developing area, a developing device back into the developer housing. The magnet roller 147 has an N2 pole and a second magnetic pole, which are first poles of the same polarity (N pole) adjacent to each other for generating a magnetic force for separating the developer after passing through the developing region from the developing sleeve 141. The N3 pole is disposed downstream of the first magnetic pole and in the vicinity of the doctor blade 146, pumps up the developer from the supply chamber 149A in the developer accommodating portion, and the doctor blade 146. This generates a magnetic force for causing the developer on the developing sleeve 141 to be spiked. In the first and second embodiments, the doctor auxiliary member 146b serving as a magnetic member having a thin plate portion is disposed on the magnetic pole facing surface that is the plate surface of the thin plate portion (the facing surface facing the outer peripheral surface of the developing sleeve) over the development effective width. 146b1 is arranged outside the outer peripheral surface of the developing sleeve on the upstream side with respect to the doctor blade 146 so that the 146b1 faces the N3 pole. As a result, as described above, even if the developer having a remarkable toner density deviation is conveyed to the magnetic field concentration area between the N3 pole and the magnetic pole facing surface 146b1, the toner density deviation is not changed after passing through the magnetic field concentration area. It is possible to improve the state in which the deviation is reduced and the deviation is reduced, and image density unevenness can be reduced.
Moreover, in the said Embodiment 1 and 2, the magnetic body member is being fixed to the doctor blade 146 as the doctor auxiliary member 146b. Thereby, rigidity can be complemented mutually.
In the first and second embodiments, the doctor auxiliary member 146b uses one plate surface portion obtained by bending the thin plate portion as the magnetic pole facing surface 146b1 toward the N3 pole, and the other plate surface portion as the doctor blade 146. The doctor auxiliary member 146b is fixed to the doctor blade 146 by joining the joint surface 146b2 to the upstream side surface of the doctor blade 146. Thereby, the effect which mutually complements rigidity can be acquired effectively.
Further, as described above, the magnetic member may be disposed at a position separated from the doctor blade 146, not as the doctor auxiliary member 146b. In this case, the distance between the developing sleeve 141 and the magnetic member can be kept constant regardless of the gap between the doctor blade 146 and the developing sleeve 141, and the toner density deviation of the developer can be leveled stably. An effect is obtained.
In the first and second embodiments, the upstream end of the magnetic pole facing surface 146b1 is located upstream of the normal at the point where the normal magnetic flux density due to the N3 pole is maximum on the developing sleeve 141. The doctor auxiliary member 146b is disposed. As a result, the magnetic field concentration region can be formed with the strongest magnetic force, so that a higher effect than leveling out the toner density deviation of the developer can be obtained.
In the first and second embodiments, the upstream end of the restriction surface of the doctor blade 146 is downstream of the normal at the point where the normal direction magnetic flux density due to the N3 pole is maximum on the developing sleeve 141. Thus, the doctor blade 146 is arranged. As a result, the developer can be cut off at the portion where the magnetic brush is densely laid, so that a stable amount of the developer deteriorated with time can be supplied to the development region.
In the first and second embodiments, the doctor base 146a of the doctor blade 146 is nonmagnetic. If the doctor base 146a of the doctor blade 146 is also made of a magnetic material, the doctor base 146a is larger than the doctor auxiliary member 146b. Therefore, more magnetic lines of force gather on the doctor base 146a side, and the magnetic lines of force toward the doctor auxiliary member 146b are reduced. The leveling effect in the magnetic field concentration region is reduced. In addition, since the magnetic lines of force are directed more toward the doctor base 146a, the magnetic force that contributes to pumping becomes insufficient, and pumping failure tends to occur. By configuring the doctor base 146a of the doctor blade 146 to be nonmagnetic as in the first and second embodiments, these problems are eliminated. The material of the doctor blade 146 is preferably stainless steel, aluminum or the like.
In the first and second embodiments, since the doctor blade 146 is disposed vertically downward with respect to the developing sleeve 141, the developer that has failed to pass through the doctor blade 146 is quickly brought into the developer accommodating chamber by its own weight. Therefore, the stress on the developer in the upstream region of the doctor blade can be reduced. In addition, since the N2 pole can be disposed above the upper surface of the developer in the developer accommodating portion, the magnet 149 can also be disposed above the upper surface of the developer in the developer accommodating portion. It is possible to suppress a situation in which the developer in the container is attracted to the magnet 149 and stays there.
In the first and second embodiments, since a large number of oval-shaped dents are randomly provided on the outer peripheral surface of the developing sleeve 141, as described above, stable and good images without causing image unevenness over a long period of time are provided. An image can be obtained.
In the second embodiment, the developer is an agitating space in which the conveying screws 142 and 143 are arranged by contacting the inner wall surface of the developing casing 144 and shielding between the developing sleeve 141 and the conveying screws 142 and 143. The sealing seal 150 as a sealing member for sealing the inside of the housing portion, and the sealing seal 150 is arranged in the direction of the rotation axis of the developing sleeve 141 so that the portion of the sealing seal 150 that contacts the inner wall surface of the developing casing is in close contact with the inner wall surface of the developing casing. A doctor auxiliary member 146b is used as a holding member that can be pulled out to the outside of the developing device. As a result, unnecessary members that do not function at all after the start of use of the developing device do not remain in the developing device, and such a member does not cause a problem that the degree of freedom of layout in the developing device is limited. . Moreover, in the said Embodiment 2, since it is not the structure which adhere | attaches the sealing seal | sticker 150 with an adhesive agent etc., it also has the effect that it becomes possible to hold down manufacturing cost compared with the structure which adhere | attaches.

10Y, 10C, 10M, 10K Image forming device 12Y, 12C, 12M, 12K Photosensitive drum 14Y, 14C, 14M, 14K Developing device 20 Optical unit 31 Intermediate transfer belt 40 Paper feeding unit 50 Fixing unit 141, 241, 341 Developing sleeve 142, 143 Conveying screw 144 Developer casing 145 Toner replenishing port 146 Doctor blade 146a Doctor base 146b Doctor auxiliary member 146b1, 646b1, 746b1 Magnetic pole facing surface 146b2, 746b2 Joining surface 147, 447 Magnet roller 148 Seal member 149 Magnet 149A Supply chamber 149A Chamber 150 Hermetic seal 181-186, 481-486 Magnetized yoke 249A First housing chamber 249B Second housing chamber 546b Magnetic sheets 646b, 746b Sky member

JP 11-194617 A JP 2007-183533 A Japanese Patent No. 4014478

Claims (14)

A developer carrying member for disposing a magnetic field generating means in a non-magnetic hollow body and carrying and transporting a two-component developer comprising a magnetic carrier and toner on the outer peripheral surface of the hollow body;
A developer accommodating portion having a supply chamber for accommodating a two-component developer carried on the developer carrying member;
An agitating and conveying member for conveying a two-component developer along the rotation axis direction of the developer carrying member;
A developer regulating member that regulates the layer thickness of the two-component developer carried on the developer carrying body,
The two-component developer carried on the developer carrying member from within the developer containing portion is regulated by the developer regulating member, and then passed through the developing region facing the latent image carrying member, and then returned to the developer containing portion again. In the developing device,
The magnetic field generating means includes adjacent first and second magnetic poles having the same polarity,
The second magnetic pole is disposed downstream of the first magnetic pole in the developer transport direction by the developer carrying member and in the vicinity of the developer regulating member, and two components from the supply chamber in the developer accommodating portion. It draws up the developer and generates a magnetic force for causing the two-component developer on the developer carrier to be spiked, which is regulated by the developer regulating member ,
End regulating surface of said developer regulating member in the developer conveyance direction upstream side by the current image-carrying member is, normal magnetic flux density according to the second magnetic pole of the point where the maximum on the developer carrying member Arrange the developer regulating member so that it is on the downstream side in the developer transport direction by the developer carrier from the normal line,
The stirring and conveying member in the supply chamber in the developer accommodating portion is driven to rotate in the same direction as the rotation direction of the developer carrying member, and the gravity direction position of the upper end of the stirring and carrying member is the lower end of the developer carrying member. The developer in the agent separation region between the first magnetic pole and the second magnetic pole on the developer carrier is disposed so as to be positioned with a gap in the gravitational direction below the position in the gravitational direction. , The outer peripheral portion of the stirring and conveying member falls from the upper side to the lower side of the supply chamber with respect to the rotation center axis of the stirring and conveying member, and the stirring and conveying member The central axis of rotation of the agitating and conveying member and the agitating and conveying member so that the developer whose outer peripheral portion moves from the lower side to the upper side is pumped from the agent separating area to the downstream side in the developer conveying direction by the developer carrier. Between the outer periphery of the Are arranged the developer separation area in the direction upwards,
A magnetic member having a thin plate portion is positioned on the outer peripheral surface of the developer carrying member upstream of the developer carrying member by the developer carrying member with respect to the developer regulating member, on the outer periphery of the developer carrying member, and at the upper end of the stirring and carrying member. Between the gravity direction position of
The end of the plate surface of the thin plate portion on the upstream side in the developer transport direction by the developer carrier is more than the normal at the point where the normal direction magnetic flux density by the second magnetic pole is maximum on the developer carrier. , so that the developer conveyance direction upstream side by the developer carrying member, a developing device which is characterized that you have placed the magnetic member. The developing device according to claim 1.
In the magnetic member, one plate surface portion obtained by bending the thin plate portion is used as a facing surface toward the second magnetic pole, and the other plate surface portion is used as a bonding surface to the developer regulating member. Yes,
The magnetic member is fixed to the developer regulating member by joining the joining surface of the magnetic member to the upstream side surface of the developer regulating member facing the upstream side of the developer conveying direction by the developer carrying member. A developing device. The developing device according to claim 1.
The magnetic member is a hollow member having therein a hollow region extending in the direction of the rotation axis of the developer carrying member, and a portion of the hollow member facing the second magnetic pole constitutes the thin plate portion. And
A developing device comprising cooling means for cooling the magnetic member by moving heat in the hollow region of the magnetic member to the outside of the hollow region. The developing device according to any one of claims 1 to 3,
The developing device according to claim 1, wherein the developer regulating member is non-magnetic. The developing device according to any one of claims 1 to 4,
The developing device, wherein the developer regulating member is arranged vertically below the developer carrying member. The developing device according to any one of claims 1 to 5,
The developing device according to claim 1, wherein the hollow body is provided with a large number of elliptical recesses on the outer peripheral surface thereof at random. Development in which a latent image carrier and a two-component developer composed of a magnetic carrier and toner are transported to a development area facing the latent image carrier and the toner is attached to the latent image on the latent image carrier for development. An image forming apparatus that integrally supports the apparatus and forms an image on the recording material by finally transferring the toner image obtained by development by the developing device from the latent image carrier onto the recording material. On the other hand, in the removable process cartridge,
A process cartridge using the developing device according to claim 1 as the developing device. A latent image carrier;
A developing device that transports a two-component developer composed of a magnetic carrier and toner to a developing region facing the latent image carrier and attaches the toner to the latent image on the latent image carrier and develops the developer;
In the image forming apparatus for forming an image on the recording material by finally transferring the toner image obtained by development by the developing device from the latent image carrier onto the recording material,
An image forming apparatus using the developing device according to claim 1 as the developing device. The image forming apparatus according to claim 8.
An image forming apparatus, wherein the magnetic carrier has a weight average particle diameter of 20 [μm] or more and 65 [μm] or less. The image forming apparatus according to claim 8 or 9,
The magnetic carrier has a magnetization intensity in a magnetic field of 1 × 10 ⁶ / 4π [A / m] of 40 [A · m ² / kg] or more and 90 [A · m ² / kg] or less. Image forming apparatus. The image forming apparatus according to any one of claims 8 to 10,
The toner has a volume average particle diameter of 3 μm or more and 8 μm or less, and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is in the range of 1.00 to 1.40. An image forming apparatus using a certain one. 12. The image forming apparatus according to claim 8, wherein:
An image forming apparatus using the toner having a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180. The image forming apparatus according to any one of claims 8 to 12,
In the toner, at least a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent are dispersed in an organic solvent, and a crosslinking and / or elongation reaction is performed in an aqueous medium. An image forming apparatus, characterized in that the toner is obtained by processing. 14. The image forming apparatus according to claim 8, wherein:
The shape of the toner is defined by a major axis r1, a minor axis r2, and a thickness r3 (where r1 ≧ r2 ≧ r3), and a ratio (r2 / r1) between the major axis r1 and the minor axis r2 is set. An image forming apparatus having a thickness in the range of 0.5 to 1.0 and a ratio (r3 / r2) of the thickness r3 to the minor axis r2 in the range of 0.7 to 1.0.

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