JP4548000B2 - Development device - Google Patents

Description

  The present invention relates to a developing device used in an electrophotographic image forming apparatus such as a copying machine, and more particularly, to a developer that autonomously controls toner density using a two-component developer containing a magnetic carrier and toner. The present invention relates to an apparatus and an image forming apparatus using the same.

JP 09-197833 A JP 2000-066497 A

  2. Description of the Related Art Conventionally, as a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine having these functions using an electrophotographic method, a static image formed on an image carrier such as a photosensitive drum is used. There are known ones in which an electrostatic latent image is visualized with a developer. As a developing method used in this type of developing device, a one-component developing method using only toner that is colored particles as a developer, and a method in which magnetic particles and toner as colored particles are mixed and stirred as a developer are used. Broadly divided into two-component development systems.

  Since the two-component developing system has many advantages such as image quality, maintainability, and stability, there are a wide variety of magnetic brush developing methods in which a developer in which toner is mixed with a magnetic carrier is conveyed and developed by a magnetic field. It is used. In this magnetic brush developing method, the toner is carried on the surface of the magnetic carrier by the electrostatic force generated by the friction between the toner and the magnetic carrier. When this toner approaches the electrostatic latent image on the image carrier, The electrostatic latent image is visualized by flying on the electrostatic latent image by an electric field formed between the electrostatic latent image carrier and the developer carrier. Further, the developer is repeatedly used while replenishing the toner consumed by the development.

  However, in such a magnetic brush development system, if the toner density (mixing ratio of toner and magnetic carrier) is not controlled to be within a certain range, toner scattering and fogging occur when the toner density increases. On the other hand, when the toner density is lowered, density spots and image omissions occur. Therefore, in order to obtain a stable image, it is necessary to keep the toner density constant.

  Therefore, in the conventional magnetic brush developing system, in order to obtain a stable image, a toner density sensor and a toner replenishing member are mounted on the developing device and control is performed to keep the toner density constant. For example, the toner density is detected by the toner density sensor, and after determining that the toner density has decreased based on the detection information, the toner supply is performed by the toner supply member.

  However, in this type of magnetic brush developing system, a toner density sensor and a toner replenishing member are indispensable, and an increase in the size and cost of the developing device cannot be avoided. Also, there is a problem that the toner density detection system is troublesome, such as creating a density patch to be detected.

  As a prior art for solving such a problem, a developing device that maintains a constant toner density without using a toner density sensor or a toner replenishing member has already been proposed. The developing device includes a developer accommodating portion that accommodates a two-component developer, and a toner accommodating portion that communicates with the developer accommodating portion and accommodates toner, and the amount of the two-component developer on the developer carrier is set. It is configured to regulate the toner concentration by regulating the toner by autonomously controlling the toner intake of the two-component developer according to the change in the toner concentration of the two-component developer on the developer carrying member. Yes (see, for example, Patent Document 1).

  This autonomous toner density control method generates a developer moving layer carried and conveyed by a developer carrying member and a developer circulating layer in which the developer circulates in the developer containing portion. The toner is taken in from the communicating toner container. In other words, when the toner is consumed in the developing process, the volume of the developer stored in the developer container is reduced, and the reduced amount of toner is supplied from the toner container to the developer container. In other words, the developer in the developer container holds the toner concentration.

  In addition, in such a developing device that autonomously adjusts the toner concentration, a developing device is also proposed in which a stirring and conveying member is provided in the developer accommodating portion and charging failure due to insufficient stirring of the developer is prevented by the stirring and conveying member. (For example, refer to Patent Document 2).

  However, in each of the above prior arts, the toner concentration is controlled by the change in the developer volume corresponding to the change in the toner concentration and the movement of the developer. The movement needs to be noticeable.

  Under such a demand, it is necessary to increase the developer density in the developer container around the developer carrier with a small amount of developer as compared with the normal two-component development method. The circulation is poor, and there are portions where the developer moves actively and portions where the movement of the developer is not active, so that the toner is not uniformly taken in. In addition, since the amount of developer is small, the absolute amount of toner contained in the developer is small, and because the developer density is high, the volume fluctuation of the developer is gradual even if the toner concentration is reduced, and the toner intake speed is increased. Due to the slowness, the toner is not sufficiently supplied onto the developer carrying member when continuously outputting high-density images with high toner consumption, and a desired density cannot be obtained.

  In addition, since the developer amount must be set small in advance, the stress applied to one magnetic carrier is increased, and the life of the magnetic carrier is shortened. That is, the running cost increases and the responsiveness is slow, so the density of the high-density image cannot be ensured.

  Further, when the developing device is arranged in an axial direction (longitudinal direction), the toner density in the axial direction becomes non-uniform, resulting in a problem of image unevenness.

  Therefore, the present applicant has already proposed a developing device as shown in FIG. 15 in order to solve the above problems.

  As shown in FIG. 15, the developing device 100 according to Japanese Patent Application No. 2004-154503 includes a developer carrier 132 that carries and conveys a two-component developer by a magnetic force, and a developer accommodating portion that accommodates the two-component developer. 133, a toner storage unit 135 that stores toner in a developer storage unit 133 so that the toner can be supplied, a developer retracting unit 134 that is adjacent to the developer storage unit 133 and communicates with the developer storage unit 133, and a developer carrier 132. A developer separating means that blocks a part of the two-component developer carried and conveyed by the developer as surplus developer and separates the surplus developer into the developer accommodating portion 133 or the developer retracting portion 134 according to the toner concentration; A developer partition member 139 that introduces the excess developer separated by the separating means into the developer accommodating portion 133 or the developer retracting portion 134 and partitions them from each other, and a plurality of members that stir and convey the developer A developer agitating / conveying member 136a, 136b is provided, and a toner supply port communicating with the toner supply path 137 is formed in the central region of the lower end of the developer partitioning member 139 in the axial direction. Both end portions in the axial direction are configured such that the two-component developer introduced into the developer retracting portion 134 flows into the developer accommodating portion 133 without taking in the toner from the toner accommodating portion 135. As a result, in addition to the fluidity change and bulk change of the two-component developer according to the toner concentration, autonomous density control is realized by utilizing the change of magnetic attraction force, and formed at the center. The toner in the toner container 135 is taken in only from the toner supply port, and the developer container 133 and the toner container 135 are shielded at both ends so that the developing device is inclined in the axial direction. This is intended to prevent the unevenness of the toner density in the axial direction due to the bias of the two-component developer.

  However, in the developing device configured as described above, for example, when the half-tone image is continuously formed, the region corresponding to approximately 1/3 of the axial end portion and the other 2/3 axial regions Differences in print density occur, and image density unevenness and so-called auger marks occur due to this difference.

  It is considered that such a phenomenon is caused by the interaction between the axial circulation flow and the circulation flow around the partition member due to the above-described configuration, and the balance between the circulation flows is lost and a toner density difference is generated in the axial direction.

  Therefore, the present invention has been made in view of the above-described problems of the prior art, and even when a high-density image such as an entire halftone image is continuously formed, an axial circulation flow and a cross-sectional circulation flow are provided. Development that can maintain a good balance and prevent the axial circulation flow from being divided, thereby maintaining a stable toner density in the axial direction of the developing device, and obtaining a high-quality image with little image fog and image density unevenness. An object is to provide an apparatus and an image forming apparatus using the same.

  In order to solve the above-described problems, a developing device of the present invention includes a developer carrying member that carries and conveys a two-component developer by magnetic force, and a developer containing unit that contains the two-component developer adjacent to the developer carrying member. A toner accommodating portion that is provided in communication with the developer carrier via the developer accommodating portion and accommodates toner so as to be supplied, and a developer retracting portion that is adjacent to the developer accommodating portion and communicates with the developer accommodating portion. A part of the two-component developer that is provided downstream of the developer carrying member in the developer carrying direction with respect to the developer accommodating portion and the developer retracting portion and is carried by the developer carrying member as a surplus developer. A developer separating means for separating the excess developer into the developer containing section or developer retracting section according to the toner concentration, and the surplus developer separated by the developer separating means for the developer containing section or developer retracting section Developer partitions that are introduced into and partitioned from each other And a plurality of developer agitating and conveying members provided in the developer accommodating portion, and the two-component developer introduced into the developer retracting portion according to the toner concentration in the developer accommodating portion is the partition member In the developing device that flows into the developer accommodating portion while taking in the toner replenished from the toner accommodating portion via the toner supply port that is provided in the substantially central portion in the axial direction and communicates with the developer accommodating portion. Between the plurality of developer agitating / conveying members, a protrusion formed along the axial direction is provided, which allows the two-component developer around the developer agitating / conveying member to flow in the cross-sectional direction. The height of the portion is characterized by gradually increasing along the transport direction of the developer agitation transport member closest to the developer carrier.

  In the present specification, the axial direction refers to the direction along the rotation axis direction of the developer carrying member, and the cross-sectional direction refers to the direction orthogonal to the axial direction.

  In the developing device that autonomously controls the toner density thus configured to keep a predetermined value, the circulating flow along the axial direction of the developer agitating and conveying member and the axial direction circulating flow are orthogonal to each other. A cross-sectional circulation flow that circulates around the member is generated.

  In the case where such an axial circulation flow and a cross-sectional circulation flow of the two-component developer are generated in the apparatus, the axial direction of the two-component developer around the developer agitating / conveying member closest to the developer carrying member The toner concentration and the flow rate tend to decrease as the toner consumption by development proceeds downstream in the transport direction. On the other hand, the cross-sectional circulation flow around the partition member in this region tends to increase conversely as the toner concentration decreases.

  Accordingly, the balance of the flow of the two-component developer is lost in the axial direction along with the change in the flow rate in the axial direction (conveying direction) between the axial direction circulating flow and the cross-sectional direction circulating flow. Tend to be non-uniform.

  Further, the two-component developer around the developer agitating / conveying member has a higher axial conveying force as the height of the wall surrounding the agitating member is higher.

  Therefore, a developing device according to the present invention configured as described above includes a developer carrying member, a developer accommodating portion, a toner accommodating portion, a developer retracting portion, a developer separating means, a developer partition member, And a plurality of developer agitating / conveying members, which are replenished from the toner accommodating portion via a toner supply port provided at a substantially central portion in the axial direction of the partition member in accordance with the toner concentration of the developer accommodating portion. In the developing device that flows into the developer accommodating portion while taking in the toner, the flow of the two-component developer in the cross-sectional direction around each developer stirring and conveying member is enabled between the plurality of developer stirring and conveying members. A protrusion formed along the axial direction, and the height of the protrusion is gradually increased along the conveyance direction of the developer agitating and conveying member closest to the developer carrying member. The conveyance direction downstream of the developer agitating and conveying member that is closest This can increase the axial conveying force of the sheet, thereby maintaining the balance between the axial direction circulation flow and the cross-sectional direction circulation flow, and suppressing the division of the axial direction circulation flow so that high-density images such as half-tone images can be continuously displayed. Even when formed, it is possible to provide a developing device capable of suppressing occurrence of a toner density difference in the axial direction of the developing device and obtaining a good image with little image fog and image density unevenness.

  The developing device according to the present invention includes a developer carrying member that carries and conveys a two-component developer by magnetic force, a developer containing unit that contains the two-component developer adjacent to the developer carrying member, and a developer containing unit. A toner container that is provided in communication with the developer carrier through the unit and accommodates toner so as to be supplied, a developer retracting part that is adjacent to the developer container and communicates with the developer container, and a developer container And a part of the two-component developer which is provided downstream of the developer carrying member with respect to the developer retracting direction with respect to the developer carrying direction and is carried and carried by the developer carrying member as an excess developer, depending on the toner concentration The developer separating means for separating the excess developer into the developer accommodating section or the developer retracting section, and the excess developer separated by the developer separating means are introduced into the developer accommodating section or the developer retracting section and A developer partition member for separating the developer A two-component developer introduced into the developer retracting portion according to the toner concentration in the developer containing portion is substantially at the center in the axial direction of the partition member. A plurality of developer agitators in the developing device that flows into the developer accommodating portion while taking in the toner replenished from the toner accommodating portion via a toner supply port provided in the portion and communicating with the developer accommodating portion; Between the conveying members, between the plurality of shielding walls, the shielding walls provided in a plurality of axial directions, disabling the flow in the cross-sectional direction of the two-component developer around each developer stirring and conveying member, A plurality of communication sections provided along the axial direction that allow the flow of the two-component developer around the developer agitating and conveying members in the cross-sectional direction are formed, and the axial length of the communication sections is , Closest to the developer carrier Characterized in that it decreases along the conveying direction of the image-agitating transporter.

  Also in the case of the developing device according to the present invention configured as described above, the axial flow of the two-component developer around the developer agitating / conveying member is disabled between the developer agitating / conveying members. A plurality of shielding walls provided in a plurality of locations, and a plurality of the walls provided along the axial direction that enables the flow of the two-component developer around the developer stirring and conveying member in the cross-sectional direction between the plurality of shielding walls. The length of the communication section in the axial direction decreases along the transport direction of the developer agitating / conveying member closest to the developer carrier, so that it is closest to the developer carrier. It is possible to increase the axial conveyance force downstream of the developer agitating and conveying member in the conveyance direction, thereby maintaining the balance between the axial circulation flow and the cross-sectional circulation flow, and suppressing the division of the axial circulation flow. High-density images such as tone images Even when formed, the occurrence of toner concentration difference in the axial direction of the developing device is suppressed, less excellent image image fog and uneven image density can be obtained and it is possible to provide a developing device.

  Here, at least one of the plurality of shielding walls may be disposed in a region corresponding to the downstream end of the toner supply port in the transport direction.

  In this case, since at least one of the plurality of shielding walls is disposed in a region corresponding to the downstream end of the toner supply port in the transport direction, two components in the cross-sectional direction from the admix auger side to the supply auger side are provided. The flow of the developer can be shielded, and the axial circulation flow that causes the axial density difference can be more reliably prevented.

  In addition, among the plurality of developer stirring and conveying members, the developer stirring and conveying member closest to the developer carrying member may be disposed below the other developer stirring and conveying members in the direction of gravity.

  In this case, among the plurality of developer agitating / conveying members, the developer agitating / conveying member closest to the developer carrying member is disposed below the other developer agitating / conveying members in the direction of gravity. The flow of the two-component developer from the agitating / conveying member to the developer agitating / conveying member closest to the developer carrying member is promoted, and the two-component developer around the closest agitating / conveying member flows through the partition plate. Accordingly, it is possible to suppress a decrease in the developer amount, thereby stably maintaining the two-component developer supply amount to the developer carrier.

  In the above, the developer partitioning member may be close to the developer carrying member with a predetermined distance, and one end side thereof may be positioned above the other end side in the gravity direction. .

  An image forming apparatus according to the present invention includes the developing device.

  According to the present invention, in a developing device of an autonomous toner density control development system that autonomously takes in toner using a two-component developer and keeps the toner density of the developer constant, a high-density image such as an entire halftone image is continuously displayed. Even when formed, the balance between the axial circulation flow and the cross-sectional circulation flow is maintained, and the division of the axial circulation flow is suppressed, thereby suppressing the occurrence of a toner density difference in the axial direction of the developing device. A high-quality image with little fogging and image density unevenness can be obtained.

<Embodiment 1>

  Embodiments according to the present invention will be described below with reference to the drawings.

  First, a schematic configuration of an image forming apparatus including a developing device according to Embodiment 1 of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the image forming apparatus 10 to which the developing device according to the present invention is applied is a photosensitive device in which a latent image is formed on the surface by a difference in electrostatic potential by irradiating image light after uniform charging. A charging device 22 for uniformly charging the surface of the photosensitive drum 21 and an exposure device 23 for irradiating the photosensitive drum 21 with image light to form a latent image on the surface are provided around the photosensitive drum 21. A developing device 24 that selectively transfers toner to a latent image on the photosensitive drum 21 to form a toner image, and the photosensitive drum 21 that faces the photosensitive drum 21 and sandwiches the recording medium 28. A transfer roll 26 for generating a transfer bias electric field and a cleaning device 29 for removing toner remaining on the photosensitive drum 21 after the transfer of the toner image are provided. The recording medium 28 is supplied from the upstream side of the facing portion (nip portion) between the photosensitive drum 21 and the transfer roll 26, and the unfixed image transferred onto the recording medium 28 is downstream. A fixing device 50 is provided that heats and melts the toner image and presses the toner image onto the recording medium 28. Here, the photosensitive drum 21 can be formed by forming a photosensitive layer made of an organic photosensitive material, an amorphous selenium photosensitive material, an amorphous silicon photosensitive material, or the like on the surface of a metal drum rotating in the direction of the arrow. . In addition, the charging device 22 is formed by coating a metal roll having conductivity such as stainless steel or aluminum with a coating of a high-resistance material, and is in contact with the photosensitive drum 21 so as to be driven to rotate. . When a predetermined voltage is applied, a continuous discharge is generated in a minute gap near the contact portion between the roll and the photosensitive drum 21, and the surface of the photosensitive drum 21 is charged almost uniformly. It is. The exposure device 23 has a laser writing device and an LED array, generates a flashing laser beam based on an image signal, and scans this in the main scanning direction of the photosensitive drum 21 by a polygon mirror. An electrostatic latent image is formed on the surface of the photosensitive drum 21. This electrostatic latent image is formed as a potential image by contrast with a high potential portion not exposed to light because the surface potential of the photosensitive drum 21 in the portion exposed to light is lowered. The developing device 24 accommodates a two-component developer composed of toner and magnetic carriers as colored particles in a housing 31, and supports the two-component developer on the developer carrier 32. By applying a developing bias from the bias power source 25, the developer carrier 32 is held at an intermediate potential between the high potential portion and the low potential portion of the electrostatic latent image, and the image portion of the electrostatic latent image is charged. The toner is developed with toner. Further, the transfer device 26 is constituted by, for example, a transfer roll disposed in contact with the photoconductive drum 21, and a transfer bias in a direction in which the toner image on the photoconductive drum 21 is attracted by the bias power source 27 is applied. The toner image on the photosensitive drum 21 is transferred to the recording medium 28. The toner remaining on the photosensitive drum 21 is removed by, for example, a doctor blade type cleaning device 29.

  Further, the fixing device 50 is, for example, a heat roll type, and includes a heating roll 51 and a pressure roll 52, and the recording medium 28 is passed between the heating roll 51 and the pressure roll 52, thereby toner. The image is fixed on the recording medium 28.

  Next, details of the developing device according to the present embodiment will be described with reference to FIGS. FIG. 2 is a plan view showing the developing device 24 according to the present embodiment, and shows a state in which the damming portion 41 is removed for simplification. 3 is a cross-sectional view taken along line XX in FIG. 2, and FIG. 4 is a cross-sectional view taken along line YY in FIG. FIG. 5 is a diagram showing the configuration of the developer agitating / conveying member, and FIG. 6 is a diagram showing the shape of the protrusion between the developer agitating / conveying members in the present embodiment.

  First, a schematic configuration of the developing device 24 according to the first embodiment will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, the developing device 24 includes a housing 31 that opens toward the photosensitive drum 21, and a developer carrier 32 is disposed facing the opening of the housing 31. Among them, a developer accommodating portion 33 having a plurality of developer agitating and conveying members 36 a and 36 b for agitating and conveying the two-component developer G accommodated in a portion adjacent to the developer bearing member 32, and the developer bearing member 32. Adjacent to the developer container 33 and communicated with the developer carrier 32 via the developer container 33 and a developer retracting part 34 provided downstream of the developer carrier 32 in the developer transport direction, A toner storage portion 35 that stores the toner T and the two-component developer G that has flowed out of the developer retracting portion 34 is formed. In addition, the toner container 35 is provided with a toner agitating and conveying member 351 that agitates and conveys the toner T and the two-component developer G flowing out from the developer retracting part 34 along the bottom wall surface of the toner accommodating part 35. ing. Further, as best shown in FIG. 4, the developer container 33 and the toner container 35 have a wall surface 40 at the axial end so that the two-component developer G cannot flow between them. Are shielded from each other.

  In the present embodiment, the two-component developer G is a developer composed of toner T and a magnetic carrier, and the toner T uses, for example, a non-magnetic toner. Magnetic toner may be used.

  The developer carrier 32 includes a rotating sleeve 321 that rotates counterclockwise, and a magnetic pole roll 322 that is fixedly disposed inside the rotating sleeve. And this magnetic pole roll 322 is comprised by the magnetic pole (S1-S3, N1-N4) of 7 poles, for example.

  Further, a damming portion 41 is disposed between the transport magnetic pole (N2) and the developing magnetic pole (S1) so as to face the developer carrier 32. The damming portion 41 has the same width as the developer carrier 32, one end is supported by the housing 31, and the tip is brought close to the developer carrier 32 with a gap of about several tens to several hundreds of μm. ing. For example, a developer separating unit that separates the two-component developer G into the developer accommodating portion 33 or the developer retracting portion according to the toner density is configured by the damming portion 41 and the magnetic pole of the developer carrier 32. Yes. In this embodiment, since a large amount of the two-component developer G is supplied to the damming portion 41, the gap between the developer partition member 39 and the developer carrying member 32, which will be described later, is separated from the damming portion 41 and the developer carrying member. It is set wider than the gap with the body 32.

  Further, a developer partition member 39 that partitions both of the developer container 33 and the developer retracting section 34 is disposed.

  The developer partition member 39 is formed with an axial width of the same level as the developer carrier 32, and is inclined obliquely downward so that the developer carrier 32 side is the upper side and the opposite side is the lower side ( In the present embodiment, the base plate 39a that is approximately 30 ° with respect to the horizontal direction is connected to the lower end of the base plate 39a and obliquely downward at a steep inclination angle (approximately 45 ° with respect to the horizontal direction). And an inclined base plate 39b. The lengths of the inclined portions of the base plates 39a and 39b are set such that the two-component developer G flowing on the inclined portions flows into the developer containing portion 33.

  In this way, the base plate 39a, which is close to the damming portion 41 and is susceptible to the pushing pressure of the two-component developer G from the damming portion 41 onto the inclined portion, is gently inclined to make the pushing pressure pressure difficult to act on. By making the slope more steep, the two-component developer G that has flowed out onto the partition member 39 can smoothly flow toward the second developer stirring member.

  In the base plate 39a, the upper end portion 39d located on the developer carrier 32 side is directly above the transport magnetic pole (N1) in the developer carrier 32 or upstream from the transport magnetic pole (N1) in the developer transport direction ( In the clockwise direction), the surface of the developer carrying member 32 is opposed to the surface at several hundred μm to several mm.

  Further, as shown in FIGS. 2 and 3, the lower end 39e of the base plate 39b opposite to the upper end 39d has a region 10B that is approximately 1/3 of the axial central portion of the side surface on the toner storage unit 35 side. The toner container 35 and the developer container 33 are communicated with each other, and the toner container 35 and the developer container 33 are communicated with a toner supply path 37 that enables toner supply to the developer container 33 while the toner from the toner container 35 is involved. A toner supply port 37a is formed. On the other hand, in the regions 10A and 10C, which are approximately 1/3 of both axial ends of the lower end 39e, as shown in FIGS. 2 and 4, the wall surface that shields the toner container 35 and the developer container 33. A predetermined distance (about 3 mm to 6 mm) is set between the two-component developer G and the two-component developer G that has flowed out onto the partition member 39 due to the separation, and the toner in the toner storage unit 35 is not taken in. It is configured to flow directly into the developer accommodating portion 33 along the inclined surface 39. Further, on the lower surface of the lower end portion 39e, the opposing surface facing the outer peripheral surface is approximately 1.5 mm from the outer peripheral surface of the stirring and conveying member 36b, following the outer peripheral surface of the second developer stirring and conveying member 36b. It is formed with a distance of ˜2 mm.

  As described above, the opening 37a of the toner supply path 37 is provided only in the substantially central portion in the axial direction of the lower end 39e of the partition member 39, and the developer containing portion 33 and the toner containing portion 35 are shielded by the partition wall 40 in the end region. As a result, the influence of the deviation of the two-component developer G can be reduced. Further, the inclined plate flow of the two-component developer G on the partition member 39 can be made to uniformly flow over the entire axial direction, whereby the amount of developer (MOS: Mass on) on the developer carrier 32 can be increased. (Sleeve) can be maintained constant, and unevenness of the image density in the axial direction due to the fluctuation of the MOS accompanying the fluctuation of the inclined plate flow can be prevented.

  The developer accommodating portion 33 has a space for accommodating the two-component developer G, and the first developer agitating / conveying member 36a (in the developer accommodating portion 33 is located near the developer carrying member 32). (Hereinafter also referred to as a supply auger), which is adjacent to the opposite side of the first developer agitating / conveying member 36a and the developer carrier 32, and whose rotation center is the rotation of the first developer agitating / conveying member 36a. It is located above the center in the gravitational direction (in this embodiment, approximately half the height of the auger shaft diameter) and is disposed substantially parallel to the first developer agitating / conveying member 36a. A second developer agitating / conveying member 36b (hereinafter also referred to as an admix auger) is provided. The first and second developer agitating / conveying members 36a and 36b have substantially the same outer diameter and rotate in opposite directions (for example, 36a is counterclockwise and 36b is clockwise). Thus, the developer reciprocally circulates from the axial end to the end of the developing device 24, and the development of the first and second developer agitating / conveying members 36a and 36b. It is possible to form a flow in which the agents are replaced with each other.

  Here, each developer agitating and conveying member 36a, 36b has a so-called spiral shape having a shaft portion 36s as shown in FIG. 5 and a wing portion 36t formed in a spiral shape on the surface of the shaft portion 36s. Consists of auger. By using such a spiral auger as a developer stirring and conveying member, it is possible to more efficiently perform circumferential stirring and axial conveyance of the developer.

  Further, the bottom shape of the developer accommodating portion 33 is formed in a curved shape along the developer carrier 32 and the developer agitating / conveying members 36a and 36b. A developer conveyance path having a predetermined interval is secured between the developer carrier 32 and the supply auger 36a, and each developer agitation and conveyance is provided between the supply auger 36a and the admix auger 36b. Protrusions extending in a predetermined axial region that can be transported in the axial direction while forming a communication path that allows the two-component developer G that is stirred and transported by the members 36a and 36b to be interchanged. A portion W is formed.

  Specifically, as shown in FIGS. 2 to 4, the protrusion W extends in a mountain shape in the axial direction in the region excluding the end turn region Re of the two-component developer G, and the top portion Wa. Has a predetermined gap between the lower end surface of the partition member 39 and is formed so as not to completely separate both the developer agitating and conveying members 36a and 36b.

  As best shown in FIGS. 6C to 6E, the height of the top portion Wa of the projection W is along the conveying direction of the supply auger 36a adjacent to the developer carrier 32. The height is gradually increased. That is, the gap between the top portion Wa of the protrusion W and the lower end surface of the partition member 39 is set to be narrower toward the downstream side in the transport direction of the supply auger 36a.

  Here, in this embodiment, the two agitating / conveying members 36a and 36b are used as the developer agitating / conveying member, but the number of arrangements is not limited to two, and the outer diameter is also limited. It is not necessarily the same.

  In addition, an agitator 351 that is a toner stirring and conveying member corresponding to the toner supply path 37 is accommodated in the toner accommodating portion. That is, as shown in FIG. 2, the agitator 351 has toner and / or a high-concentration developer (hereinafter also referred to as toner) in a region that is approximately 1/3 of the central portion in the axial direction corresponding to the region 10B. A transport blade 351a that transports the toner toward the toner supply path 37 is attached to the support member 351c. On the other hand, in the end regions other than the central portion 1/3 corresponding to the regions 10A and 10C, the blades that collect the toner and the like of the toner storage portion 35 in the central portion 1/3 are inclined with respect to the axis. A bent-up scraping fin 351b is attached to the support member 351c. Note that the blades in this end region may have a coil auger shape instead of the scraping fins.

  As described above, the toner in the toner storage unit 35 is formed so as to be concentrated in the axial region 10B corresponding to the width of the toner supply port 37a. The supply path 37 can be quickly supplied.

  Further, as shown in FIG. 3, a regulating portion 40a having a flat top portion is formed in the central region 10B on the wall surface 40 on the toner containing portion 35 side forming the toner supply path 37. In order to prevent excessive toner or high-concentration developer from being pushed into the developer containing portion 33 side, the restricting portion 40a temporarily accumulates toner on the upper portion of the toner supply path 37.

  Next, an outline of the operation of the developing device 24 according to the present embodiment will be described with reference to FIG.

  In FIG. 2, the two-component developer G in the developer accommodating portion 33 is agitated by the developer agitating / conveying member 36 and captured by the scooping magnetic pole (N 3) in the developer carrier 32. After that, the captured two-component developer G is separated from the developer carrier 32 (rotating sleeve 321) by the magnetic attraction force of the drawing magnetic pole (N3) and the transport magnetic pole (S3) and the frictional force between the surface of the developer carrier 32. ) In the rotation direction. When the transported two-component developer G reaches the vicinity of the damming portion 41 constituting a part of the developer separating means, the transported magnetic pole (N1) acting as a trimming magnetic pole forms a spike. Further, the rising of the two-component developer G is regulated by the damming portion 41, so that the developer layer is formed on the developer carrier 32, and this developer layer is conveyed to the development area. . Further, the developer layer of the two-component developer G transported to the development area forms a magnetic brush by the magnetic attraction force of the developing magnetic pole (S1), and the toner T in the two-component developer G that forms this magnetic brush. Makes the electrostatic latent image on the photosensitive drum 21 visible by a developing electric field formed between the photosensitive drum 21 and the developer carrier 32.

  In the developing device 24 configured as described above, for example, in the case of the two-component developer G having a low toner concentration, the apparent permeability increases because the magnetic carrier density per unit volume is relatively large. The magnetic attractive force per developer unit volume with respect to the developer carrier 32 is increased. For this reason, since the frictional force with the developer carrier 32 is increased and the conveying force is increased, the developer carrier 32 is surely conveyed to the damming portion 41 and overcomes the damming force of the damming portion 41. The staying developer staying in the vicinity of 41 is pushed out. The pushed-out staying developer becomes a falling developer and falls onto the developer partition member 39, passes through the developer retracting portion 34, and then flows into the developer accommodating portion 33 or the toner accommodating portion 35.

  As described above, when the two-component developer G having a low toner concentration is led to the developer retracting portion 34, a space is made in the developer accommodating portion 33, and as a result, development from the toner accommodating portion 35 is performed. The two-component developer G that has been in the toner supply path 37 up to the agent container 33 is quickly drawn into the space by the conveying force of the developer agitating / conveying member 36 and the weight of the two-component developer G. The two-component developer G in the vicinity of the supply path 37 flows. As a result, the toner supply path 37 receives the toner T and the two-component developer G having a very high toner density from the toner container 35, and the toner T and the two-component developer G having a very high toner density are supplied to the toner supply path 37. The toner is quickly supplied to the developer accommodating portion 33 through the supply path 37. Here, the two-component developer G having a very high toner concentration means that the two-component developer that has flowed out of the developer retracting portion 34 into the toner accommodating portion 35 is agitated and mixed with the toner in the toner accommodating portion 35, and the magnetic carrier. Is a two-component developer having a very high toner ratio.

  On the other hand, in the case of the two-component developer G having a high toner concentration, since the magnetic carrier density per unit volume is relatively small, the apparent magnetic permeability is reduced, and the developer carrier 32 has a unit density per unit volume. The magnetic attraction force becomes smaller. For this reason, since the conveying force by the developer carrier 32 is reduced, most of the two-component developer G on the developer carrier 32 is more than the tip of the developer partition member 39 with respect to the rotation direction of the developer carrier 32. Will fall at the upstream position. As a result, the two-component developer G falls at a position upstream from the upper end portion 39d of the developer partition member 39 without pushing out the staying developer staying in the vicinity of the damming portion 41, and directly the developer accommodating portion. Return to 33. At this time, unlike the case where the toner density is low, no space is created in the developer accommodating portion 33 and the two-component developer G in the vicinity of the toner supply path 37 does not flow. The toner T and the two-component developer G having a very high toner density are not supplied from the toner container 35.

  As described above, the toner replenishment mechanism according to the present embodiment uses the change in magnetic attraction force in addition to the change in fluidity and bulk of the two-component developer G in accordance with the toner concentration. The toner is supplied to the two-component developer G having a low toner density, and the toner is not supplied to the two-component developer G having a high toner concentration.

  In the developing device 24 configured as described above, the toner T and the two-component developer G having a very high density in the toner container 35 can be quickly taken into the developer container 33, so that a high-density image can be obtained. In addition to being able to cope with continuous output, the stress on the developer is reduced, and the life of the developer can be extended and the running cost can be reduced.

  Further, the axial ends of the developer accommodating portion 33 and the toner accommodating portion 35 are shielded from each other by the wall surface 40 so as to prevent the two-component developer G from flowing therethrough and separated into the developer retracting portion 34. The two-component developer G thus supplied is supplied to the developer accommodating portion 33 while taking in the toner in the toner accommodating portion 35 through the toner supply port 37a provided at the substantially central portion of the lower end portion 39e of the partition member 39. Therefore, even when the developing device 24 is inclined in the axial direction, the developer backflow from the developer containing portion 33 side to the toner containing portion 35 side accompanying the inclined arrangement, In addition to preventing an excessive inflow of toner from the toner container 35 side to the developer container 33 side, a difference in height of the developer at both axial ends of the toner supply path 37 due to the inclination is reduced. Accordingly, it is possible to provide a developing device that suppresses the occurrence of an axial toner density difference due to the axially inclined arrangement and obtains a high-quality image with little image fog and image density unevenness.

  Further, in the end region other than the axial width of the toner supply port 37a capable of taking in the toner, the two-component developer introduced onto the developer partition member 39 is developed without taking in the toner from the toner containing portion 35. Since the inclined plate flow of the two-component developer G on the partition member 39 flows uniformly into the entire width direction, the developer flow flowing on the partition member 39 flows into the agent storage portion 33. The flow speed of the developer is uniform in the axial direction of the developer carrier 32, and the partial layer formation amount variation on the developer carrier 32 based on the unevenness of the inclined plate flow on the partition member 39 does not occur. A uniform print density can be obtained.

  By the way, of the plurality of augers 36a and 36b described above, the supply auger 36a adjacent to the developer carrier 32 conveys the two-component developer G in the right direction in the figure as exemplified in FIG. The far-side admix auger 36b serves to eliminate the uneven toner density in the axial direction by conveying the two-component developer G to the left side in the drawing. Further, when the toner concentration in the developer accommodating portion 33 decreases, a flow that circulates around the partition member 39 (hereinafter referred to as a cross-sectional flow) is generated, and the toner from the toner accommodating portion 35 is taken in. Fulfill.

  It has been found that in the transport method in which the two types of flows occur simultaneously, a phenomenon of occurrence of a unique toner density difference in the axial direction occurs.

  Hereinafter, this phenomenon will be described with reference to a developing device based on the comparative configuration example shown in FIGS. Here, in the developing device according to the comparative configuration example shown in FIG. 8 and FIG. 15, the supply auger 136a and the admix auger 136b are arranged substantially horizontally, and the supply auger 136a and the admix auger 136b are interposed between them. The height of the top portion Wa of the formed protrusion W is formed constant in the axial direction.

  As shown in FIG. 8, the flow of the two-component developer G in this comparative configuration example causes the two-component developer G flowing on the partition member 139 to flow from the toner containing portion 135 in the width region in the axial direction 10B. The toner again flows into the admix auger 136b in the developer accommodating portion 133 while taking in the toner. A part of the toner or high-density developer that has flowed into the admix auger 136b flows over the protrusion W to the supply auger 136a side, and the remaining developer is left in the figure by the admix auger 136b. In the direction, the sheet is folded at the developer end folding section Re and conveyed rightward in the drawing by the supply auger 136a. Here, the supply auger 136a has a role of transporting the developer to the right in the axial direction while supplying the developer to the developer carrier 132, so that the developer on the developer carrier 132 contributes to the development. When the toner is consumed, the developer toner density on the developer carrier 132 tends to decrease as it goes from upstream to downstream (left to right in the figure) in the conveyance direction of the supply auger 136a.

  On the other hand, the flow amount in the cross-sectional direction tends to increase toward the downstream side of the supply auger 136a where the toner concentration decreases based on the above-described operating principle. Note that, in the width region of 10B in the figure, the flow in the cross-sectional direction flows in the cross-sectional direction while taking in the toner from the toner container 135, so that a decrease in the toner density on the developer carrier 132 is suppressed. In the width region of 10 and 10B, the toner density difference between the two is not so noticeable.

  However, since the flow R as shown in FIG. 8 occurs in the 10C width region, the axial circulation flow is divided in the 10A, 10B region and the 10C region. This flow R is generated according to the following mechanism. (1) In the vicinity of the boundary position between the 10B and 10C regions on the side of the admix auger 136b, the developer is bulky due to the inclined plate flow on the partition member 139 and the accompanying toner intake from the toner container 135. is there. Therefore, the developer to be transported from the 10C region to the 10B region by the admix auger 136b is hindered by the bulky developer in the vicinity of the boundary position, and makes a U-turn toward the supply auger 136a in the 10C region. (2) On the other hand, the developer transport amount from the 10B region on the supply auger 136a side to the 10C region is reduced in the axial transport amount to the 10C region due to the cross-sectional flow generated in the 10B region. There is not enough developer to fill. As described above, independent axial circulation flows are formed in the 10C region by (1) and (2).

  For this reason, in the 10C region, toner is consumed by development in a state where no toner is taken in from the toner storage unit 135, so that the toner concentration in this region is partially reduced, and print density axial unevenness occurs. End up.

  Therefore, in the developing device 24 according to the present embodiment, the height of the top portion Wa of the projection W formed between the supply auger 36a and the admix auger 36b is set to the conveyance of the supply auger 36a as described above. By gradually increasing along the direction, the occurrence of uneven toner density in the axial direction can be suppressed as follows.

  As shown in FIG. 9A, in general, the auger obtains the conveying force in the axial direction by the developer sliding down on the inclined surface of the spiral portion (blade portion) 36t according to gravity. The transport amount greatly varies depending on the shape of the wall surrounding the auger and the distance between the wall and the auger. For example, as shown in FIG. 9B, when the wall is the axial height of the auger shaft 36s, the developer on the spiral portion at a position higher than the axial height escapes in the radial direction (cross-sectional direction). Does not contribute to direction transport. Therefore, as shown in FIG. 9C, the auger axial transportability is improved as the wall height approaches the top height of the auger diameter. In the present embodiment, as shown in FIG. 6, the height of the top Wa of the protrusion W located between the two agitating and conveying members 36a and 36b gradually increases along the conveying direction of the supply auger 36a. The developer transport amount in the axial direction increases as the supply auger 36a moves downstream in the transport direction. On the other hand, the flow amount in the cross-sectional direction increased on the downstream side in the transport direction of the supply auger 36a as the toner was consumed, and the balance with the axial circulation flow rate was lost. Thus, the height of the protrusion W is reduced to the supply auger 36a. By forming so as to increase gradually along the conveying direction, it is possible to maintain the balance between the cross-sectional direction circulation flow rate and the axial direction circulation flow rate, and to prevent the above-described phenomenon that the axial direction circulation flow is divided.

Further, as in the present embodiment, when the inclined plate flow on the partition member 39 is uniformly present in the axial direction, the developer from the supply auger 36a passes through the partition member 39 and is on the side of the admix auger 36b. Therefore, the amount of developer on the supply auger 36a side tends to be smaller than the amount of developer on the admix auger 36b side. However, in this embodiment, the supply auger 36a is further replaced with the admix auger 36b. The flow of the developer from the admix auger 36 b to the supply auger 36 a is promoted, and the developer around the supply auger 36 a flows via the partition member 39. Maintains stable transport performance by preventing the decrease in developer amount due to toner and the delay in toner replenishment to the downstream end in the transport direction. Rukoto can. In addition, the developer supply amount to the developer carrier 32 can be stably maintained, and auger marks can be prevented from being generated.
<Embodiment 2>

  Next, a developing device according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 9 is a front view showing the developing device 24A according to the present embodiment.

  The developing device 24A according to the present embodiment is configured to change the protrusion W according to the previous embodiment and to provide a plurality of communication sections between the developer stirring and conveying members 36a and 36b. The same reference numerals are given to the same members as those in the embodiment, and the description thereof is omitted. An image forming apparatus to which the developing device according to this embodiment can be applied is also the same as that of the previous embodiment, and a description thereof will be omitted.

  As shown in FIG. 10, in the developing device 24A according to the present embodiment, a partial partition wall PW is formed in a predetermined region between the supply auger 36a and the admix auger 36b. Specifically, the partial partition wall PW protrudes from the bottom of the developer accommodating portion 32 so as to allow the two-component developer G to flow between the supply auger 36a and the admix auger 36b in the cross-sectional direction, The protrusion D is formed so that its top height is substantially the same as the rotation axis height of the admix auger 36b, and the supply auger 36a and the admix auger 36b In order to disable the flow of the two-component developer G in the cross-sectional direction between the two, the regulating portions K1 to K3 projecting from the bottom of the developer accommodating portion 32 and connected to the lower end surface of the partition member 39 are configured. ing. Further, the regulation sections K1 to K3 define a plurality of communication sections A1 to A3 between the supply auger 36a and the admix auger 36b, and these communication sections A1 to A3 are downstream in the transport direction of the supply auger 36a. The restricting portions K1 to K3 are arranged so as to narrow toward the side. That is, the axial widths of the communication sections A1 to A3 are formed such that A1> A2> A3.

  Further, at least one of the regulating portions K1 to K3 (K2 in the drawing) is arranged in a region corresponding to the end portion 37r of the toner supply port 37a on the downstream side in the transport direction of the supply auger 36a. Yes. More specifically, the restricting portion K2 is disposed so as to block an area corresponding to the downstream end portion 37r of the toner supply port 37a by 10 mm to 20 mm.

  As described above, the developing device 24A according to the second embodiment in which the protruding sections D and the regulating sections K1 to K3 form the communication sections A1 to A3 that become narrower toward the downstream side in the transport direction of the supply auger 36a. The same effect as in the embodiment can be obtained.

  Further, the restricting portion K2 shields the flow of the developer in the cross-sectional direction from the admix auger 36b to the supply auger 36a in the region corresponding to the downstream end portion 37r of the supply auger 36a of the toner supply port 37a. Therefore, the cross-sectional flow R (see FIG. 8) that divides the axial circulation flow described above can be more reliably interrupted, and the balance between the axial circulation flow and the cross-sectional circulation flow is ensured. It is possible to prevent a phenomenon in which the toner density in the axial direction is not uniform due to collapse. Thereby, stabilization of the toner density in the axial direction can be realized, and an image with little density unevenness in the axial direction can be obtained.

  Next, results of performance verification of the developing devices 24 and 24A according to the present embodiment will be shown as examples below.

  First, specific specifications of the developing device used in this embodiment will be described with reference to FIG.

  In FIG. 3, the magnetic pole roll 322 (made of Al, surface roughness Rz = 20 μm) of the developer carrier 32 is φ16 mm, seven magnetic poles are arranged, and the rotation speed is set to 406 rpm, as shown in FIG. The one having such a magnetized pattern was used.

  Further, the supply auger 36a and the admix auger 36b were both those having an outer diameter of 10 mm, a shaft diameter of 5 mm, and a pitch of 14 mm, and the rotation speed was 460 rpm.

  As the agitator 351, a PET film having a thickness of 0.1 mm was used for both the fin portions at both ends and the central sheet portion, and the number of rotations was 20 rpm.

The damming portion (layer regulating member) 41 is made of SUS having a thickness of 1.5 mm, and the gap with the developer carrier 32 is set to 0.3 mm so that the unit area weight after regulation is 35 mg / cm ² . .

  As the toner, a polyester toner containing 20% magnetic powder and having a volume average particle size of 6.5 μm was used. As the carrier, a ferrite carrier having a volume average particle diameter of 50 μm was used. The developer amount was 200 g.

Further, the distance (DRS) between the photosensitive drum 21 and the developer carrier 32 in the development area is 0.3 mm, the development pole setting angle (MSA) is 3 °, the charging potential (Vh) is −550 V, and the latent image potential. (VL) was set to −100 V to −120 V, the developing bias (DC) was set to −440 V, and the axial width of the toner supply port 37a at the center was set to 92 mm.
<Verification evaluation 1>

  Under the above conditions, first, based on the developing device 24 according to the first embodiment, performance verification was performed on toner uptake performance. The verification result is shown in FIG.

  As shown in FIG. 12, the drive unit side (side on which the drive mechanism is attached), the central portion, and the counter drive unit side in the axial direction of the developing device 24 are promptly driven to a predetermined saturation after the developing device 24 is driven. It is understood that the toner concentration converges to the toner concentration (about 10%) and thereafter the saturated toner concentration is stably maintained.

This is because, when the developing device is configured as in the present embodiment, the toner can be stably taken in without losing the balance between the axial circulation flow and the cross-sectional circulation flow of the developer, This shows that the toner concentration in the axial direction is uniformly stable. Similar verification results were obtained for the developing device 24A according to the second embodiment.
<Verification evaluation 2>

  Next, using the developing device 100 according to the comparative configuration example and the developing device 24 according to the first embodiment, respectively, after continuously forming five A4 solid images, Cin 33% (the total number of dots on the image electronic data) A halftone image having a black dot ratio of 33%) was created, and the print density distribution in the axial direction was measured for comparative evaluation. The measurement results are shown in FIG.

As shown in FIG. 13, in the developing device 100 according to the comparative configuration example, the halftone density is reduced at the end portion in the axial direction, and the density difference is about 0.1 at the maximum. In the developing device 24 according to aspect 1, it can be seen that the axial halftone density is substantially uniform and the density difference is about 0.02 at the maximum. Similar verification results were obtained for the developing device 24A according to the second embodiment.
<Verification evaluation 3>

  Next, regarding the axial toner density distribution after five continuous A4 solid images are formed, the developing device 100 according to the comparative configuration example, the developing device 24 according to the first embodiment, and the developing device 24A according to the second embodiment. Measurements were made for each. The measurement results are shown in FIG.

  As can be understood from FIG. 14, in the developing device 100 according to the comparative configuration example, it can be seen that the toner density is decreased on the side opposite to the driving unit. This is because, in the developing device 100, the non-driving unit side is located downstream in the transport direction of the supply auger 36a, and the toner density corresponding to the downstream region in the transport direction is caused by the phenomenon of the axial circulation flow as described above. Is thought to have been reduced.

  On the other hand, in both of the developing devices 24 and 24A according to the first and second embodiments, the toner concentration decreases on the downstream side in the transport direction of the supply auger 36a as seen in the comparative configuration example. It can be seen that, in any of the developing devices according to any of the embodiments, the phenomenon of the axial circulation flow is improved and a stable toner density is maintained in the axial direction.

  Thus, according to the developing devices 24 and 24A according to the present embodiment, the axial toner density can be stably maintained even when the axial circulation flow and the cross-sectional circulation flow coexist. It is possible to prevent deterioration in the quality of the formed image due to uneven toner density in the axial direction.

1 is a configuration diagram showing a schematic configuration of an image forming apparatus according to the present invention. It is a top view which shows the developing device which concerns on Embodiment 1 of this invention. It is sectional drawing along the XX line of FIG. It is sectional drawing along the YY line of FIG. It is a schematic block diagram which shows the structure of a developing agent stirring conveyance member. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the image development apparatus which concerns on Embodiment 1 of this invention, (a) is a front view, (b) is a side view, (c)-(e) is each sectional drawing in an axial direction. It is a figure explaining the condition of the axial direction circulation flow and cross-sectional direction circulation flow of a two-component developer. It is a figure explaining the division phenomenon of an axial circulation flow. It is a figure explaining the conveyance condition of the developer by a developer stirring conveyance member, (a) is a schematic diagram which shows a conveyance condition, (b), (c) demonstrates the relationship between a developer stirring conveyance member and a wall. It is a schematic diagram. FIG. 4 is a diagram illustrating a configuration of a developing device according to a second embodiment, where (a) is a front view and (b) is a side view. It is a figure which shows the magnetization pattern of the 7 pole magnetic pole roll of the image development apparatus used in the Example. FIG. 4 is a diagram illustrating toner uptake characteristics of the developing device according to the first embodiment. It is a figure which shows the measurement result of the print density of the axial direction in each developing device at the time of forming a halftone image after forming 5 continuous images using the developing device according to the comparative configuration example and the first embodiment. FIG. 10 is a diagram illustrating measurement results of toner density distribution in the axial direction in each developing device after forming five continuous images using the developing device according to the comparative configuration example and the first and second embodiments. It is a schematic block diagram which shows the structure of the developing device which concerns on the comparative structural example.

Explanation of symbols

  10: image forming device, 21: photosensitive drum, 22: charging device, 23: exposure device, 24, 24A: developing device, 25: bias power source, 26: transfer device, 27: bias power source, 28: recording medium, 29, cleaning device, 31: housing, 32: developer carrier, 33: developer accommodating portion, 34: developer retracting portion, 35: toner accommodating portion, 36a: supply auger, 36b: admix auger, 36s: shaft Part, 36t: wing part, 37: toner supply path, 37a: toner supply port, 39: developer partition member, 39a, 39b: base plate, 39d: upper end part, 39e: lower end part, 40: wall surface, 40a: regulating part 41: Damping part, 50: Fixing device, 51: Heating roll, 52: Pressure roll 100: Developing device, 132: Developer carrier, 133: Developer container 134: developer retracting part, 135: toner accommodating part, 136: developer stirring and conveying member, 137: toner supply path, 139: developer partitioning member, 321: rotating sleeve, 322: magnetic pole roll, 351: agitator, 351: Toner agitating and conveying member, 351a: conveying blade, 351b: fin, 351c: support member, A1, A2, A3: communicating section, D: protrusion, K1, K2, K3: regulating section, PW: partial partition, R: cross section Directional flow, Re: folding region, W: protrusion, Wa: top

Claims (6)

A developer carrier that carries and transports the two-component developer by magnetic force, a developer container that contains the two-component developer adjacent to the developer carrier, and a developer carrier that communicates with the developer carrier via the developer container. A toner accommodating portion that accommodates toner so as to be supplied, a developer retracting portion that is adjacent to the developer accommodating portion and communicates with the developer accommodating portion, and a developer with respect to the developer accommodating portion and the developer retracting portion A part of the two-component developer that is provided on the downstream side in the developer conveying direction of the carrier and is carried and carried by the developer carrier is blocked as an excess developer, and a developer storage unit or a developer retracting unit depending on the toner concentration A developer separating means for separating the excess developer, a developer partitioning member for introducing the surplus developer separated by the developer separating means into the developer accommodating section or the developer retracting section and partitioning the developer from each other, and a developer A plurality of developers provided in the container And a拌搬feed member, according to the toner density of the developer accommodating portion, a two-component developer introduced into the developer saving unit is provided at a substantially central portion in the axial direction of the developer partition member, developing In the developing device that flows into the developer accommodating portion while taking in the toner replenished from the toner accommodating portion via the toner supply port communicating with the agent accommodating portion,
The plurality of developer agitating / conveying members are set in a conveying direction so as to generate an axial circulation flow along the axial direction, and the developer partitioning member includes a developer accommodating portion and a developer carrying member. Is circulated around the developer partitioning member , and is arranged so as to generate a cross-sectional circulation flow orthogonal to the axial circulation flow.
Between the plurality of developer agitating and conveying members, along the axial direction, which allows the two-component developer to flow in the cross-sectional direction between the developer agitating and conveying members constituting a part of the circulating flow in the cross-sectional direction. A developing device comprising: a formed projecting portion, wherein the height of the projecting portion is gradually increased along a transport direction of a developer agitating and transporting member closest to the developer carrying member. A developer carrier that carries and transports the two-component developer by magnetic force, a developer container that contains the two-component developer adjacent to the developer carrier, and a developer carrier that communicates with the developer carrier via the developer container. A toner accommodating portion that accommodates toner so as to be supplied, a developer retracting portion that is adjacent to the developer accommodating portion and communicates with the developer accommodating portion, and a developer with respect to the developer accommodating portion and the developer retracting portion A part of the two-component developer that is provided on the downstream side in the developer conveying direction of the carrier and is carried and carried by the developer carrier is blocked as an excess developer, and a developer storage unit or a developer retracting unit depending on the toner concentration A developer separating means for separating the excess developer, a developer partitioning member for introducing the surplus developer separated by the developer separating means into the developer accommodating section or the developer retracting section and partitioning the developer from each other, and a developer A plurality of developers provided in the container And a拌搬feed member, according to the toner density of the developer accommodating portion, a two-component developer introduced into the developer saving unit is provided at a substantially central portion in the axial direction of the developer partition member, developing In the developing device that flows into the developer accommodating portion while taking in the toner replenished from the toner accommodating portion via the toner supply port communicating with the agent accommodating portion,
The plurality of developer agitating / conveying members are set in a conveying direction so as to generate an axial circulation flow along the axial direction, and the developer partitioning member includes a developer accommodating portion and a developer carrying member. Is circulated around the developer partitioning member , and is arranged so as to generate a cross-sectional circulation flow orthogonal to the axial circulation flow.
Between the plurality of developer agitating / conveying members, shielding walls provided at a plurality of positions in the axial direction that disable flow of the two-component developer between the developer agitating / conveying members in the cross-sectional direction, and the plurality of the developer agitating / conveying members. A plurality of communication sections provided along the axial direction that allow the two-component developer to flow in the cross-sectional direction between the developer stirring and conveying members constituting a part of the circulating flow in the cross-sectional direction between the shielding walls. And the length in the axial direction of the communication section decreases along the transport direction of the developer agitation transport member that is closest to the developer carrier.   The developing device according to claim 2, wherein at least one of the plurality of shielding walls is disposed in a region corresponding to a downstream end portion of the toner supply port in the transport direction.   2. The developer agitating and conveying member closest to the developer carrying member among the plurality of developer agitating and conveying members is disposed below the other developer agitating and conveying members in the direction of gravity. The developing device according to claim 3.   The developer partitioning member is close to the developer carrying member with a predetermined distance, and has one end side positioned on the upper part in the gravitational direction as compared with the other end side. Item 5. The developing device according to any one of Items 1 to 4.   An image forming apparatus comprising the developing device according to claim 1.

Images