JP2018092098A - Development device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the agitation property of toner supplied from a toner supply unit with a simple configuration even in a state where the height of the developer surface on the upstream side in the developer conveyance direction of an agitation chamber is low in a function separation type development device.SOLUTION: In a function separation type development device, when being attached to an image formation apparatus, an agitation screw rotates in the direction heading to the lower side in the vertical direction of a recovery chamber from the direction heading to a partition wall. In the development device, one end part of a developer guide unit is arranged close to a developer carrier when viewed at the cross section orthogonal to the rotation axis of the agitation screw, and the other end part of the developer guide unit is arranged on the upper side in the vertical direction of the region of the agitation screw being on the side closer to a partition wall from the rotation center of the agitation screw. In the development device, the developer guide units are continuously provided at two pitches or more of blade parts of the agitation screw on the downstream side in the developer conveyance direction of the agitation screw with respect to the toner supply unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a developing device for developing an electrostatic latent image.

  In the developing device described in Patent Document 1, a function of supplying a developer containing toner and a magnetic carrier to a developer carrying member and a function of collecting the developer from the developer carrying member are separated from each other. This is a mold developing device. In this developing device, a developing chamber for supplying the developer to the developer carrying member and a partition member for partitioning the stirring chamber for stirring the developer are provided below the developer carrying member with respect to the direction of gravity. A developing chamber is disposed, and an agitating chamber is disposed opposite the developer carrier. In the developing device, the partition member is provided with a developer guide that guides the developer separated from the surface of the developer carrying member in the developer peeling region so that the developer is collected from the developer carrying member into the stirring chamber. Yes.

  The agitation chamber is provided with a toner replenishing unit for replenishing toner to a circulation path through which the developer circulates between the agitation chamber and the developing chamber. From the toner replenishing portion, uncharged toner is replenished. The toner replenished from the toner replenishing unit is mixed and stirred with the developer in the stirring chamber, thereby being contacted with the magnetic carrier in the developer in the stirring chamber and frictionally charged. By frictional charging, the toner is negatively charged and the magnetic carrier is positively charged. The frictionally charged toner is attached and held on the surface of the magnetic carrier by electrostatic force.

  The toner weight is significantly smaller than the magnetic carrier weight. For this reason, toner that has just been replenished from the toner replenishing portion and is not charged (that is, toner that is not held on the surface of the magnetic carrier) floats on the developer surface of the agitation chamber, and the developer surface of the agitation chamber It is conveyed so as to slide up. Then, the toner (upslip toner) in a state of sliding upward on the developer surface in the stirring chamber is transported to the most downstream side in the developer transport direction of the stirring chamber without being sufficiently mixed and stirred with the developer in the stirring chamber. Then, the toner in a state where charging failure has occurred is transferred from the stirring chamber to the developing chamber.

  Therefore, the toner replenished from the toner replenishing part is sufficiently mixed and stirred with the developer in the agitating chamber before the toner replenished from the toner replenishing part is conveyed to the most downstream in the developer conveying direction of the agitating chamber. Need to be.

  As one of the methods for improving the agitation property of the toner replenished from the toner replenishing unit, in the developing device described in Patent Document 2, a vibration plate as a vibration member is disposed vertically below the toner replenishing port. . In this developing device, the amount of developer charged in the stirring chamber is increased so that the free end of the vibration plate is inserted into the developer in the stirring chamber, and the height of the developer surface in the stirring chamber is increased. ing.

JP 2011-28216 A JP 2013-186371 A

  In the function separation type developing device, the developer is transported from the upstream side to the downstream side in the developer transport direction of the stirring chamber, and the developer is recovered from the developer carrier. For this reason, in the function separation type developing device, the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is lower than the height of the developer surface on the downstream side in the developer conveying direction of the stirring chamber. There is a tendency.

  In the function separation type developing device, even when the diaphragm as in Patent Document 1 is arranged, the toner replenishing unit is in a state where the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low. The effect of increasing the stirring property of the toner replenished from the toner cannot be expected.

  In the function separation type developing device, even if the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low, the toner replenished from the toner replenishing unit can be easily configured. It is desirable to increase the stirring ability.

  The present invention has been made in view of the above problems. An object of the present invention is to provide a toner replenishing unit with a simple configuration even in a state where the height of the developer surface on the upstream side in the developer transport direction of the stirring chamber is low in the function separation type developing device. It is an object of the present invention to provide an apparatus capable of improving the stirring property of toner replenished from the toner.

  In order to achieve the above object, a developing apparatus according to an aspect of the present invention has the following arrangement. That is, a developer carrier that is rotatably provided and carries a developer containing toner and a magnetic carrier, and is arranged below the developer carrier in the direction of gravity, and supplies the developer to the developer carrier. A supply chamber, disposed opposite to the developer carrier, a collection chamber for collecting the developer from the developer carrier, and disposed in the supply chamber, and conveys the developer in the supply chamber in the first direction. A first screw portion that is disposed in the recovery chamber, and a rotatable rotation shaft, and a spiral blade provided on an outer periphery of the rotation shaft, and the developer in the recovery chamber is disposed in the first direction. A second screw portion that conveys in a second direction opposite to the first direction, and a guide portion for guiding the developer to be collected from the developer carrying member into the collection chamber. A partition wall separating the recovery chamber, and disposed in the recovery chamber; And a toner replenishing unit for replenishing toner in a circulation path through which the developer circulates between the chamber and the recovery chamber, wherein the developing device is included in an image forming apparatus that forms an image on a recording material. When mounted, the second screw part rotates in a direction from the direction toward the partition to the lower side in the vertical direction of the recovery chamber, and when viewed in a cross section perpendicular to the rotation axis of the second screw part, One end portion of the guide portion is disposed in proximity to the developer carrier, and the other end portion of the guide portion is located on the side closer to the partition wall from the rotation center of the second screw portion. It is disposed vertically above the region, and the guide portion is provided continuously at least two pitches of the blade portion of the second screw portion on the downstream side of the toner replenishment portion in the second direction. Features.

  According to the present invention, in the function-separated type developing device, the toner replenishing unit has a simple configuration even when the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low. The agitation of the toner replenished from the toner can be improved.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus. It is sectional drawing which shows the structure of a function separation type developing apparatus. It is sectional drawing which shows the structure of the guide part which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the guide part which concerns on a comparative example. It is a top view which shows the structure of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure (modified example) of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure (modified example) of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure (modified example) of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure (modified example) of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure (modified example) of the guide part which concerns on 1st Embodiment. It is a top view which shows the structure of the guide part which concerns on a comparative example. It is a top view which shows the structure of the guide part which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the present invention according to the claims, and all the combinations of features described in the present embodiments are not necessarily essential to the solution means of the present invention. . The present invention can be implemented in various applications such as printers, various printing machines, copiers, FAX machines, and multifunction machines.

[First Embodiment]
(Configuration of image forming apparatus)
First, the configuration of the image forming apparatus according to the first embodiment of the present invention will be described with reference to the cross-sectional view of FIG.

  The image forming apparatus 10 includes an endless intermediate transfer belt (ITB) 24 as an intermediate transfer member, and 4 from the upstream side to the downstream side along the rotation direction of the intermediate transfer belt 24 (the direction of arrow R24 shown in FIG. 1). Two image forming units St (StY, StM, StC, StK) are provided. Each of the image forming units St (StY, StM, StC, StK) is mounted on the image forming apparatus 10 so as to be replaceable (detachable).

  Further, the toner bottles 34 (34Y, 34M, 34C, 34K) of each color of Y (yellow), M (magenta), C (cyan), and Bk (black) are mounted on the image forming apparatus 10. Each of the toner bottles 34 (34Y, 34M, 34C, 34K) is mounted so as to be replaceable (detachable) with respect to the image forming apparatus 10.

  Each of the image forming units St (StY, StM, StC, StK) includes a rotatable photosensitive drum 28 (28Y, 28M, 28C, 28K) as an image carrier. Each of the photosensitive drums 28 (28Y, 28M, 28C, 28K) is formed with a photosensitive layer having a negative charge polarity on the outer peripheral surface of the aluminum cylinder. At the time of image formation, each of the photosensitive drums 28 (28Y, 28M, 28C, 28K) is rotationally driven in the direction of arrow R28 shown in FIG. 1 at a predetermined process speed.

  In the image forming unit StY, a yellow toner image is formed on the photosensitive drum 28Y, and the yellow toner image formed on the photosensitive drum 28Y is transferred to the intermediate transfer belt 24. In the image forming unit StM, a magenta toner image is formed on the photosensitive drum 28M, and the magenta toner image formed on the photosensitive drum 28M is transferred to the intermediate transfer belt 24. In the image forming unit StC, a cyan toner image is formed on the photosensitive drum 28C, and the cyan toner image formed on the photosensitive drum 28C is transferred to the intermediate transfer belt 24. In the image forming unit StK, a black toner image is formed on the photosensitive drum 28K, and the black toner image formed on the photosensitive drum 28K is transferred to the intermediate transfer belt 24.

  Around the photosensitive drum 28 (28Y, 28M, 28C, 28K), a charging roller 21 as a charging unit is arranged along the rotation direction (arrow R28 direction) of the photosensitive drum 28 (28Y, 28M, 28C, 28K). (21Y, 21M, 21C, 21K) are provided.

  The charging roller 21 (21Y, 21M, 21C, 21K) is in contact with the photosensitive drum 28 (28Y, 28M, 28C, 28K), and is directed toward the photosensitive drum 28 (28Y, 28M, 28C, 28K) by a pressure spring. Is energized. At the time of image formation, the charging roller 21 (21Y, 21M, 21C, 21K) rotates following the photosensitive drum 28 (28Y, 28M, 28C, 28K). For example, a charging bias (DC voltage: −900 V, AC peak-to-peak voltage: 1500 V) is applied to the charging roller 21 (21Y, 21M, 21C, 21K) from a high-voltage power source as an application unit. As a result, the photosensitive drum 28 (28Y, 28M, 28C, 28K) is uniformly charged.

  Further, around the photosensitive drum 28 (28Y, 28M, 28C, 28K), an exposure device 22 (22Y, 22M, as a latent image forming unit) is arranged along the rotation direction of the photosensitive drum 28 (direction of arrow R28). 22C, 22K).

  The exposure device 22 (22Y, 22M, 22C, 22K) irradiates the photosensitive drum 28 (28Y, 28M, 28C, 28K) charged with the charging roller 21 (21Y, 21M, 21C, 21K) with laser light. A laser beam scanner provided with a semiconductor laser. The exposure device 22 (22Y, 22M, 22C, 22K) is a photosensitive drum 28 (28Y) charged by a charging roller 21 (21Y, 21M, 21C, 21K) based on an image signal input to the image forming apparatus 10. , 28M, 28C, 28K).

  Further, a developing device 1 (1Y, 1M, 1C, 1K) as a developing unit is disposed around the photosensitive drum 28 (28Y, 28M, 28C, 28K).

  The developing device 1 (1Y, 1M, 1C, 1K) generates an electrostatic latent image formed on the photosensitive drum 28 (28Y, 28M, 28C, 28K) by the exposure device 22 (22Y, 22M, 22C, 22K). Developing with developer (toner). As a result, toner adheres to the exposed portions (laser light irradiated portions) on the photosensitive drum 28 (28Y, 28M, 28C, 28K), and a visible image is formed.

  The developing device 1 (1Y, 1M, 1C, 1K) is mounted so as to be replaceable (detachable) with respect to the image forming apparatus 10 and contains a two-component developer (also simply referred to as a developer) including toner and a magnetic carrier. A developing container. Details of the developing device 1 (1Y, 1M, 1C, 1K) will be described later with reference to FIG.

  A primary transfer roller 23 (23Y, 23M, 23C, 23K) as a primary transfer unit is disposed around the photosensitive drum 28 (28Y, 28M, 28C, 28K).

  The primary transfer rollers 23 (23Y, 23M, 23C, 23K) are pressed against the surface of the intermediate transfer belt 24 sandwiched between the photosensitive drums 28 (28Y, 28M, 28C, 28K) with a predetermined pressing force. . As a result, primary transfer nip portions T1 (T1Y, T1M, T1C, T1K) as primary transfer portions are formed.

  Negative transfer toner formed on the photosensitive drum 28 (28Y, 28M, 28C, 28K) by applying a positive DC voltage (transfer bias) to the primary transfer roller 23 (23Y, 23M, 23C, 23K). The image is primarily transferred onto the intermediate transfer belt 24.

  Further, around the photosensitive drum 28 (28Y, 28M, 28C, 28K), a photosensitive cleaner 26 (26Y, 26) for collecting toner remaining on the photosensitive drum 28 without being primarily transferred to the intermediate transfer belt 24. 26M, 26C, 26K).

  The intermediate transfer belt 24 is stretched around a primary transfer roller 23 (23Y, 23M, 23C, 23K), a stretching roller 31, a secondary transfer counter roller 29, and a tension roller 30.

  The secondary transfer counter roller 29 also serves as a drive roller. As the secondary transfer counter roller 29 rotates in the rotation direction (arrow R29 direction shown in FIG. 1), the intermediate transfer belt 24 rotates in the arrow R24 direction. The rotation speed of the intermediate transfer belt 24 is set to be approximately the same as the rotation speed (process speed) of the photosensitive drum 28 (28Y, 28M, 28C, 28K).

  A secondary transfer roller 32 as a secondary transfer unit is disposed at a position corresponding to the secondary transfer counter roller 29 on the surface of the intermediate transfer belt 24. The intermediate transfer belt 24 is sandwiched between the secondary transfer counter roller 29 and the secondary transfer roller 32. Thus, a secondary transfer nip portion T2 as a secondary transfer portion is formed between the secondary transfer roller 32 and the intermediate transfer belt 24.

  A recording material 27 (for example, paper or transparent film) used for image formation is stored in a state of being stacked on a feeding cassette 51 as a sheet storage unit. Then, the recording material 27 is supplied from the feeding cassette 51 to the secondary transfer nip portion T2 by a feeding / conveying device having a feeding roller, a conveyance roller, a registration roller, and the like.

  A transfer bias is applied to the secondary transfer roller 32, and the toner image formed on the intermediate transfer belt 24 is transferred onto the recording material 27.

  A belt cleaner 33 as an intermediate transfer member cleaner is in contact with a position corresponding to the tension roller 30 on the surface of the intermediate transfer belt 24. The transfer residual toner slightly remaining on the intermediate transfer belt 24 after the secondary transfer is scraped off and collected by the belt cleaner 33.

  A fixing device 25 having a fixing roller 25a and a pressure roller 25b is disposed downstream of the secondary transfer nip T2 in the conveyance direction of the recording material 27. The fixing device 25 fixes the toner image transferred onto the recording material 27. Then, the recording material 27 subjected to the fixing process by the fixing device 25 is discharged out of the apparatus (for example, a discharge tray).

(Reference example of function-separated type development device)
In the developing device 1 according to the first embodiment, a function of supplying a developer to a developing sleeve as a developer carrying member (hereinafter referred to as a supply mechanism) and a function of recovering the developer from the developing sleeve (hereinafter referred to as recovery). This is a so-called function separation type developing device in which the mechanism is separated. Prior to the description of the developing device 1 according to the first embodiment, the configuration of the function separation type developing device will be described with reference to the cross-sectional view of FIG. FIG. 2 is a cross-sectional view of the developing device 100 (functional separation type developing device) in a cross section orthogonal to the rotation axis of the developing sleeve.

  The developing device 100 is mounted in a replaceable (detachable) manner with respect to the image forming apparatus 10 and includes a developing container 2 that contains a two-component developer (hereinafter simply referred to as a developer) containing a magnetic carrier and a non-magnetic toner. Have. The non-magnetic toner is obtained by encapsulating a colorant, a wax component or the like in a resin such as polyester or styrene acryl, and pulverizing or polymerizing it. The magnetic carrier is obtained by applying a resin coat to the surface layer of a core made of resin particles kneaded with ferrite particles or magnetic powder. By frictional charging, the toner is negatively charged and the magnetic carrier is positively charged.

  The developing container 2 is provided with an opening at a position corresponding to the developing region facing the photoconductor drum 28. The developing container 2 is provided with a developing sleeve 3 as a developer carrying member. The developing sleeve 3 is rotatably arranged at a position facing the photosensitive drum 28 so that a part of the developing sleeve 3 is exposed to the opening of the developing container 2. The developing sleeve 3 is made of a nonmagnetic material such as SUS or aluminum, and rotates in the direction of the arrow R3 shown in FIG. 2 during the developing operation.

  Inside the developing sleeve 3, a magnet roll (magnet) 4 as a magnetic field generating means having a plurality of magnetic poles along the rotation direction (arrow R3 direction) of the developing sleeve 3 is fixedly disposed. In the example of FIG. 2, the magnet roll 4 has five magnetic poles: S1 pole, S2 pole, N1 pole, N2 pole, and N3 pole.

  The plurality of magnetic poles of the magnet roll 4 are adjacent to the “first magnetic pole” and the “first magnetic pole” downstream of the “first magnetic pole” in the rotation direction (arrow R3 direction) of the developing sleeve 3. It includes a “second magnetic pole” that is disposed and has the same polarity as the “first magnetic pole”. A repulsive magnetic field is formed between adjacent magnetic poles of the magnet roll 4 (referring to “first magnetic pole” and “second magnetic pole”), and a low magnetic force region is formed between adjacent magnetic poles of the magnet roll 4. Arise. Since the developer is peeled off from the surface of the developing sleeve 3 in this low magnetic force region, the low magnetic force region is also called a developer peeling region. In the example of FIG. 2, the N3 pole of the magnet roll 4 corresponds to a “first pole”, and the N1 pole of the magnet roll 4 corresponds to a “second magnetic pole”. In the example of FIG. 2, a repulsive magnetic field is formed between the N3 pole and the N1 pole of the magnet roll 4, and a low magnetic force region is generated between the N3 pole and the N1 pole.

  The inside of the developing container 2 is partitioned into a developing chamber 11 and a stirring chamber 12 by a partition wall 15 extending in the vertical direction. As shown in FIG. 2, the developing chamber 11 and the stirring chamber 12 are arranged side by side in the horizontal direction. As shown in FIG. 2, the developing chamber 11 is disposed below the developing sleeve 3 with respect to the direction of gravity, and the stirring chamber 12 is disposed to face the developing sleeve 3.

  The partition wall 15 is provided with a guide portion 160 for guiding the developer peeled off from the developing sleeve 3 in the developer peeling region so that the developer is directly collected in the stirring chamber 12. The guide 160 may be configured integrally with the partition wall 15 or may be configured separately from the partition wall 15.

  The guide portion 160 is formed with an inclined surface that is inclined with respect to the bottom surface of the developing container 2 when the developing device 100 is attached to the image forming apparatus 10. The guide portion 160 is disposed in the vicinity of the developing sleeve 3 so as to face a low magnetic force region (developer peeling region) between adjacent magnetic poles of the magnet roll 4. In addition, although the starting point of the guide portion 160 as one end portion of the guide portion 160 (also referred to as an end portion of the guide portion near the developing sleeve 3) faces the developing sleeve 3 of the guiding portion 160, the developing sleeve 3 There is no contact with the surface. On the other hand, in the configuration of the conventional function separation type developing device, the end point of the guide unit 160 as the other end portion of the guide unit 160 (also referred to as the end of the guide unit far from the developing sleeve 3) is the upper end of the partition wall 15. Located in the department.

  In the function separation type developing apparatus according to the present invention, the structure of the guide portion is different from that of the conventional function separation type developing apparatus (FIG. 2). Therefore, details of the guide unit according to the present invention will be described later with reference to FIG.

  In the developing chamber 11, a first screw portion 13 as a rotatable developer transporting member that stirs and transports the developer in the developing chamber 11 along the longitudinal direction (rotational axis direction) of the developing sleeve 3. They are arranged substantially in parallel. The first screw portion 13 includes a rotating shaft 13a of a magnetic material as a rotatable shaft portion extending over substantially the entire length of the developing chamber 11, and a developer transport provided along the outer periphery of the rotating shaft 13a. A spiral blade portion 13b as a portion is provided. The first screw portion 13 rotates in the direction of arrow R13 shown in FIG.

  The agitating chamber 12 has a second screw portion 14 as a rotatable developer conveying member that agitates the developer in the agitating chamber 12 and conveys the developer in the direction opposite to the first screw portion 13. 3 are arranged substantially in parallel along the longitudinal direction (rotation axis direction). The second screw portion 14 has a rotating shaft 14a of a magnetic body as a rotatable shaft portion extending over substantially the entire length of the stirring chamber 12, and a developer transport provided along the outer periphery of the rotating shaft 14a. A spiral blade portion 14b as a portion is provided. The second screw portion 14 rotates in the direction opposite to the rotation direction (arrow R13 direction) of the first screw portion 13 (arrow R14 direction shown in FIG. 2).

  Each of the developing sleeve 3, the first screw portion 13, and the second screw portion 14 is connected through the same gear train, and receives a driving force transmitted from a motor as a driving source provided in the image forming apparatus 10. receive. Thereby, each of the developing sleeve 3, the first screw part 13, and the second screw part 14 is rotationally driven.

  A first communication port as a delivery part (communication part) for delivering the developer from the developing chamber 11 to the stirring chamber 12 is provided at one end of the partition wall 15 in the longitudinal direction of the partition wall 15. That is, the developer can be communicated from the developing chamber 11 to the stirring chamber 12 through the first communication port. The other end of the partition wall 15 in the longitudinal direction of the partition wall 15 is provided with a second communication port as a transfer portion (communication portion) for transferring the developer from the stirring chamber 12 to the developing chamber 11. That is, the developer can be communicated from the stirring chamber 12 to the developing chamber 11 via the second communication port.

  The developer in the developing chamber 11 is transported from the upstream side to the downstream side in the developer transport direction by the first screw portion 13. The developer in the stirring chamber 12 is transported from the upstream side to the downstream side in the developer transport direction by the second screw unit 14. Thus, the first screw portion 13 and the second screw portion 14 transport the developer in the opposite directions along the longitudinal direction (rotational axis direction) of the developing sleeve 3. Then, a developer flow conveyed by the first screw portion 13 and a developer flow conveyed by the second screw portion 14 are formed via the first communication port and the second communication port. That is, the developer is transferred from the developing chamber 11 to the stirring chamber 12 via the first communication port, and the developer is transferred from the stirring chamber 12 to the developing chamber 11 via the second communication port. Is called.

  The developing container 2 is provided with a regulating blade 5 as a developer regulating member that forms a thin layer of developer on the surface of the developing sleeve 3. In the example of FIG. 2, the regulating blade 5 is opposed in the vicinity of the S1 pole of the magnet roll 4. A predetermined amount of developer is carried on the surface of the developing sleeve 3 by the magnetic field generated by the magnet roll 4 and the developer in the developing chamber 11 forms a developer pool. In the example of FIG. 2, the developer in the developing chamber 11 is pumped up near the N1 pole of the magnet roll 4. When the developing sleeve 3 rotates, the developer on the surface of the developing sleeve 3 passes through the developer reservoir, the layer thickness thereof is regulated by the regulating blade 5, and the developing area facing the photosensitive drum 28. Be transported. Then, the developer on the surface of the developing sleeve 3 rises in the developing area to form a magnetic spike. In the example of FIG. 2, magnetic spikes are formed near the N2 pole of the magnet roll 4.

Subsequently, the magnetic brush formed in the developing region is brought into contact with the photosensitive drum 28, and the toner in the developer carried on the surface of the developing sleeve 3 is supplied to the photosensitive drum 28, whereby the photosensitive drum 28. The electrostatic latent image on the surface of the toner is developed as a toner image. At this time, in order to improve the toner application rate (development efficiency) to the electrostatic latent image, normally, a developing bias in which an AC component is superimposed on a predetermined DC component V _dev [V] is applied to the developing sleeve 3. Is done.

  The developer on the surface of the developing sleeve 3 after the toner is supplied to the photosensitive drum 28 (hereinafter referred to as a developer after development) is rotated by the developing sleeve 3 in the direction of the arrow R3. It is conveyed to a repulsive magnetic field formed between adjacent poles. The developed developer is peeled off from the surface of the developing sleeve 3 by receiving a magnetic repulsive force by the repulsive magnetic field. The developed developer is peeled off from the surface of the developing sleeve 3 by receiving a magnetic repulsive force and falls onto the inclined surface of the guide portion 160. The developer that has fallen on the inclined surface of the guide unit 160 slides down on the inclined surface of the guide unit 160 due to gravity, whereby the developed developer is collected into the stirring chamber 12.

  As described above, in the function separation type developing device, the developed developer peeled off from the surface of the developing sleeve 3 in the developing process is not collected in the developing chamber 11 but directly in the stirring chamber 12. Collected. As described above, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developing step is collected in the stirring chamber 12, and therefore, the stirring chamber 12 is also referred to as a collection chamber. Further, the developer in the developing chamber 11 is supplied to the developing sleeve 3 by the first screw portion 13. Thus, since the developer is supplied from the developing chamber 11 to the developing sleeve 3, the developing chamber 11 is also referred to as a supply chamber. In the function separation type developing device, the developer is transported by the second screw portion 14 from the upstream to the downstream in the developer transport direction in the stirring chamber 12, and the developer peeled off from the developing sleeve 3 is guided. It has a path that is conveyed to the stirring chamber 12 via the section 160.

  When the developing device 100 is attached to the image forming apparatus 10, a toner supply mechanism for supplying toner to the developing container 2 is disposed above the stirring chamber 12 in the vertical direction. Further, the stirring chamber 12 is provided with a toner replenishing section for replenishing toner to a circulation path through which the developer circulates between the stirring chamber 12 and the developing chamber 11.

  The toner contained in the toner bottle 34 is transported to the toner replenishing mechanism through the toner transport path, and then passes through the toner replenishing portion and falls into the stirring chamber 12. As a result, the toner stored in the toner bottle 34 is supplied to the developing container 2. The toner stored in the toner bottle 34 (hereinafter referred to as replenishment toner) includes the same type of toner as the developer (hereinafter referred to as initial developer) stored in the developing device 100 at the time of shipment. It is used.

  The toner charge amount Q / M of the two-component developer containing toner and magnetic carrier is an important parameter that determines the density of the developed image. In addition, there is a correlation between the weight ratio (toner concentration T / D) of the toner contained in the two-component developer and the toner charge amount Q / M.

  From the toner replenishing portion, uncharged toner is replenished. The toner replenished from the toner replenishing unit is mixed and stirred with the developer in the stirring chamber 12, thereby being brought into contact with the magnetic carrier in the developer in the stirring chamber 12 and frictionally charged. By frictional charging, the toner is negatively charged and the magnetic carrier is positively charged. The frictionally charged toner is attached and held on the surface of the magnetic carrier by electrostatic force. Therefore, the toner charge amount Q / M increases as the contact with the magnetic carrier increases. In the two-component developer, the smaller the toner density T / D, the greater the chance that the toner will come into contact with the magnetic carrier, so the toner charge amount Q / M increases. When developing the same electrostatic latent image on the surface of the photosensitive drum 28, the density of the developed image is larger when the toner charge amount Q / M is larger than when the toner charge amount Q / M is small. There is a relationship that decreases.

  In the developing step of developing the electrostatic latent image on the surface of the photosensitive drum 28, a developer that circulates in the circulation path formed between the developing chamber 11 and the stirring chamber 12 (hereinafter, the developer in the circulation path) The toner in the developer is consumed, but the magnetic carrier in the developer in the circulation path is not consumed. Therefore, the toner concentration T / D of the developer in the circulation path is always detected using a magnetic permeability sensor provided in the stirring chamber 12. More specifically, the average magnetic permeability of the developer is detected by a magnetic permeability sensor, and the weight ratio of toner in the developer in the circulation path is calculated from the detected value. Then, the toner supply amount from the toner supply mechanism to the developing container 2 is adjusted so that the toner concentration T / D of the developer in the circulation path becomes substantially constant. For example, it is assumed that the weight ratio of the toner to the weight of the developer replenished from the toner replenishing unit is 100%, and the toner concentration of the initial developer (weight ratio of the toner contained in the developer) is 8%. . In this case, when the weight ratio of the toner in the developer in the circulation path is less than 8%, the toner supply mechanism supplies the developer container so that the toner concentration T / D of the developer in the circulation path becomes a constant value. 2 is replenished with toner.

  The toner replenishing section is desirably provided upstream of the stirring chamber 12 in the developer transport direction. This is because the section in which the toner replenished from the toner replenishing part (toner in an uncharged state) is agitated in the agitating chamber 12 by the second screw part 14 is made as long as possible to develop the inside of the agitating chamber 12. This is to allow sufficient mixing and stirring with the agent.

  The toner weight is significantly smaller than the magnetic carrier weight. For this reason, toner that has just been replenished from the toner replenishing portion and is not charged (that is, toner that is not held on the surface of the magnetic carrier) floats on the developer surface of the stirring chamber 12 and develops in the stirring chamber 12. It is conveyed so as to slide on the surface. When the toner sliding on the developer surface of the stirring chamber 12 is transported to the most downstream side in the developer transport direction of the stirring chamber 12 without being sufficiently mixed and stirred with the developer of the stirring chamber 12. Then, the toner in a state where charging failure has occurred is transferred from the stirring chamber 12 to the developing chamber 11.

  Therefore, the toner replenished from the toner replenishing unit is sufficiently mixed with the developer in the agitating chamber 12 before the toner replenished from the toner replenishing unit is conveyed to the most downstream in the developer conveying direction of the agitating chamber 12. It needs to be stirred.

  In the function separation type developing device, the developer is conveyed from the upstream side to the downstream side in the developer conveying direction of the stirring chamber 12, and the developer is collected from the developing sleeve 3. For this reason, in the function separation type developing device, the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber 12 is higher than the height of the developer surface on the downstream side in the developer conveying direction of the stirring chamber 12. It tends to be lower.

  In the function separation type developing device, even if the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low, the toner replenished from the toner replenishing unit can be easily configured. It is desirable to increase the stirring ability. In the first embodiment, in the function separation type developing device, even if the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low, toner replenishment is achieved with a simple configuration. An apparatus capable of enhancing the agitation of toner replenished from the section is provided. Details will be described below.

  The structure of the guide part which concerns on 1st Embodiment is demonstrated using sectional drawing of FIG. 3 (A) and FIG. 3 (B). FIGS. 3A and 3B show cross-sectional views of the stirring chamber 12 in a cross section orthogonal to the rotation axis of the second screw portion 14.

  3A and 3B, the same reference numerals as those in FIG. 2 denote the same constituent members. The configuration of the guide unit is different between the configuration of the function separation type developing device according to the first embodiment and the configuration of the function separation type development device illustrated in FIG. 2. Therefore, in FIGS. 3A and 3B, the reference numerals of the guide portions are different from those in FIG. The guide unit 16 according to the first embodiment may be configured integrally with the partition wall 15 or may be configured separately from the partition wall 15.

  3A and 3B, the region M is a partition wall from the rotation center P of the second screw portion 14 with a straight line L0 passing through the rotation center P of the second screw portion 14 parallel to the gravity direction as a boundary. The area | region of the 2nd screw part 14 in the side close | similar to 15 is shown. Further, the region N is formed on the side wall 18 facing the partition wall 15 of the stirring chamber 12 from the rotation center P of the second screw portion 14 with a straight line L0 passing through the rotation center P of the second screw portion 14 parallel to the gravity direction as a boundary. The area | region of the 2nd screw part 14 in the near side is shown.

  In the example of FIG. 3A, the second screw portion 14 rotates clockwise. That is, in the example of FIG. 3A, when viewed in a cross section perpendicular to the rotation axis of the second screw portion 14, when the developing device 1 is mounted on the image forming apparatus 10, the second screw portion 14 is It rotates in a direction from the direction toward the partition wall 15 to the lower side in the vertical direction of the stirring chamber 12.

  On the other hand, in the example of FIG. 3B, the second screw portion 14 rotates counterclockwise. That is, in the example of FIG. 3B, when the developing device 1 is mounted on the image forming apparatus 10 when viewed in a cross section orthogonal to the rotation axis of the second screw part 14, the second screw part 14 is It rotates in a direction from the direction toward the partition wall 15 to the upper side in the vertical direction of the stirring chamber 12.

  When the second screw portion 14 rotates in the same rotation direction as in FIG. 3A, the second screw portion 14 brings the toner supplied from the toner supply portion and the developer in the stirring chamber 12 closer to the partition wall 15. Will rotate. In addition, when the second screw portion 14 rotates in the same rotation direction as in FIG. 3A, the height of the developer surface in the region M tends to be lower than the height of the developer surface in the region N. is there. At this time, the toner replenished from the toner replenishing portion is conveyed while sliding on the developer surface in the region M where the height of the developer surface is relatively low. Therefore, the upslip toner exists on the developer surface in the region M over the entire region M. FIG. 3A schematically shows part of the upslip toner that exists on the developer surface over the entire area M.

  Therefore, in the example of FIG. 3A, the end point Q of the guide portion 16 (the end portion of the guide portion 16 on the side far from the developing sleeve 3) exceeds the joint portion T between the upper end portion of the partition wall 15 and the guide portion 16. To the region M. In other words, the end point Q of the guide portion 16 is on the side closer to the partition wall 15 from the rotation center P of the second screw portion 14 with a straight line L0 parallel to the direction of gravity passing through the rotation center P of the second screw portion 14 as a boundary. The second screw portion 14 is disposed above the area in the vertical direction. As a result, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the guide portion 16 slides down on the inclined surface of the guide portion 16 due to gravity. Drops on the developer surface at M.

  As described above, when the second screw portion 14 is rotated in the same rotation direction as that in FIG. 3A, the upslip toner is uniformly present in the region M on the developer surface in the region M. . For this reason, the developed developer that slides down on the inclined surface of the guide portion 16 by gravity and falls on the developer surface in the region M collides with the upslip toner that exists uniformly in the region M. As a result, the lump of the upslip toner is loosened, and the surface area where the upslip toner comes into contact with the developer conveying surface of the blade part 14b of the second screw part 14 is increased. Therefore, the stirrability between the toner replenished from the toner replenishing portion and the developer in the stirrer chamber 12 can be improved.

  On the other hand, when the second screw portion 14 rotates in the same rotation direction as that in FIG. 3B, the second screw portion 14 supplies the toner supplied from the toner supply portion and the developer in the stirring chamber 12 to the side wall 18. It rotates in the direction approaching (namely, the direction away from the partition 15). In addition, when the second screw portion 14 rotates in the same rotation direction as in FIG. 3B, the height of the developer surface in the region N tends to be lower than the height of the developer surface in the region M. is there. At this time, the toner replenished from the toner replenishing portion is conveyed while sliding up the developer surface in the region N where the height of the developer surface is relatively low. Therefore, the upslip toner is uniformly present in the region N on the developer surface in the region N. FIG. 3B schematically shows a part of the upslip toner existing on the developer surface over the entire area N.

  Therefore, in the example of FIG. 3B, the end point Q of the guide portion 16 (the end portion of the guide portion 16 on the side far from the developing sleeve 3) exceeds the joint portion T between the upper end portion of the partition wall 15 and the guide portion 16. To the region N. In other words, the end point Q of the guide portion 16 is on the side closer to the side wall 18 from the rotation center P of the second screw portion 14 with a straight line L0 parallel to the direction of gravity passing through the rotation center P of the second screw portion 14 as a boundary. The second screw portion 14 is disposed above the area in the vertical direction. As a result, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the guide portion 16 slides down on the inclined surface of the guide portion 16 due to gravity. Drops on the developer surface at N.

  As described above, when the second screw portion 14 rotates in the same rotation direction as in FIG. 3B, the upslip toner is present uniformly over the area N on the developer surface in the area N. . For this reason, the developed developer that slides down on the inclined surface of the guide portion 16 due to gravity and falls on the developer surface in the region N collides with the upslip toner that exists uniformly in the region N. As a result, the lump of the upslip toner is loosened, and the surface area where the upslip toner comes into contact with the developer conveying surface of the blade part 14b of the second screw part 14 is increased. Therefore, the stirrability between the toner replenished from the toner replenishing portion and the developer in the stirrer chamber 12 can be improved.

  Then, the structure of the guide part 16 which concerns on a comparative example is demonstrated using sectional drawing of FIG. 4 (A) and FIG. 4 (B). 4A and 4B show cross-sectional views of the stirring chamber 12 in a cross section orthogonal to the rotation axis of the second screw portion 14. 4A and 4B, the same reference numerals as those in FIGS. 3A and 3B denote the same constituent members.

  In the example of FIG. 4A, the second screw portion 14 rotates in the same rotation direction as that in FIG. On the other hand, in the example of FIG. 4B, the second screw portion 14 rotates in the same rotation direction as that in FIG.

  In the example of FIG. 4A, the end point Q of the guide portion 16 (the end portion of the guide portion 16 far from the developing sleeve 3) extends beyond the junction T between the upper end portion of the partition wall 15 and the guide portion 16. N is extended. As a result, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the guide portion 16 slides down on the inclined surface of the guide portion 16 due to gravity. Drops on the developer surface at N.

  As described above, when the second screw portion 14 is rotated in the same rotation direction as that in FIG. 3A, the upslip toner is uniformly present in the region M on the developer surface in the region M. . For this reason, there is a possibility that the developed developer that slides down on the inclined surface of the guide portion 16 due to gravity and falls on the developer surface in the region N collides with the upslip toner that exists uniformly in the region M. Is extremely low. Therefore, in the example of FIG. 4A, since the lump of the upslip toner is not loosened, the effect of improving the stirring property between the toner supplied from the toner supply unit and the developer in the stirring chamber 12 cannot be expected.

  In the example of FIG. 4B, the end point Q of the guide portion 16 (the end portion of the guide portion 16 far from the developing sleeve 3) extends beyond the junction T between the upper end portion of the partition wall 15 and the guide portion 16. It is extended to M. As a result, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the guide portion 16 slides down on the inclined surface of the guide portion 16 due to gravity. Drops on the developer surface at M.

  As described above, when the second screw portion 14 rotates in the same rotation direction as in FIG. 3B, the upslip toner is present uniformly over the area N on the developer surface in the area N. . For this reason, there is a possibility that the developed developer that slides down on the inclined surface of the guide portion 16 due to gravity and falls on the developer surface in the region M collides with the upslip toner that exists uniformly in the region N. Is extremely low. Therefore, in the example of FIG. 4B, since the lump of the upslip toner is not loosened, the effect of improving the agitation between the toner replenished from the toner replenishing portion and the developer in the agitating chamber 12 cannot be expected.

  Then, the structure of the guide part 16 in 1st Embodiment is demonstrated using the top view of FIG. FIG. 5 shows a planar configuration when the developing device 1 is viewed from above in the vertical direction. In the example of the developing device 1 according to FIG. 5, it is assumed that the second screw portion 14 rotates in the same rotation direction as that in FIG.

  As described above, uncharged toner is supplied to the stirring chamber 12 from the toner supply unit. Therefore, in order to frictionally charge the toner replenished from the toner replenishing portion with the magnetic carrier in the developer in the stirring chamber 12, the toner replenished from the toner replenishing portion is sufficiently mixed with the developer in the stirring chamber 12.・ It needs to be stirred. Therefore, in the developer transport direction of the stirring chamber 12, the toner replenishing portion is disposed upstream of the second communication port as a delivery portion (communication portion) for delivering the developer from the stirring chamber 12 to the developing chamber 11. Is done. Further, it is preferable that the section in which the toner replenished from the toner replenishing unit is agitated in the agitating chamber 12 by the second screw portion 14 is made as large as possible.

  Therefore, in the example of FIG. 5, in the developer conveying direction of the second screw unit 14, the toner supply port 17 as a toner supply unit transfers the developer from the developing chamber 11 to the stirring chamber 12 (communication). Part) is arranged so as to face the first communication port.

  Here, the relationship between the position of the guide portion 16 relative to the position of the toner supply port 17 and the length in the longitudinal direction of the guide portion 16 in the developer conveyance direction of the stirring chamber 12 will be described.

  As described above, in the first embodiment, the developer (upsliding toner) replenished from the toner replenishing port 17 collides with the developed developer that has slid down on the inclined surface of the guide portion 16 due to gravity. It is characterized by that.

  The upslip toner is present downstream of the toner supply port 17 in the developer conveying direction of the stirring chamber 12. For this reason, the guide unit 16 needs to be provided at least on the downstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17.

  Further, as the continuous length in the longitudinal direction of the guide portion 16 becomes shorter, the development slipped on the inclined surface of the guide portion 16 due to gravity with respect to the toner (upslip toner) supplied from the toner supply port 17. Opportunities to collide later developer are reduced. When the chance of colliding the developer after development with the upslip toner is reduced, the degree of loosening of the upslip toner is reduced, so that the toner supplied from the toner supply unit and the developer in the stirring chamber 12 are agitated. The effect of enhancing the properties will be reduced.

  Therefore, the continuous length in the longitudinal direction of the guide portion 16 continues at least two pitches of the blade portion 14b of the second screw portion 14 on the downstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17. Must be length. Further, the continuous length in the longitudinal direction of the guide portion 16 continues for at least 4 pitches of the blade portion 14b of the second screw portion 14 on the downstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17. It is preferable to make the length. This is because the longer the total length in the longitudinal direction of the guide portion 16 (the total length of the guide portions 16) is, the greater the post-development that slides down on the inclined surface of the guide portion 16 due to gravity with respect to the upslip toner. This is because it is possible to increase the chance of colliding the developer.

  For example, when the pitch of the blade portions 14b of the second screw portion 14 is 20 [mm], the continuous length in the longitudinal direction of the guide portion 16 is greater in the developer conveyance direction of the stirring chamber 12 than the toner supply port 17. On the downstream side, the length needs to be 40 [mm] or more. Note that the pitch of the blade portions 14b of the second screw portion 14 being 20 [mm] means that the blade portions 14b have a spiral structure centering on the rotation shaft 14b with a period of 20 [mm]. .

  In the example of FIG. 5, the guide portion 16 is provided so as to face substantially the entire region where the developer is coated on the surface of the developing sleeve 3 (hereinafter referred to as the developer coating region of the developing sleeve). Specifically, the guide unit 16 is located downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12 and immediately downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12. 8 pitches of the blade portion 14b of the two screw portion 14 are continuously provided.

  Moreover, in the example of FIG. 5, since the 2nd screw part 14 is rotating in the same rotation direction as FIG. 3 (A), the end point Q of the guide part 16 is as shown in FIG. It is assumed that the region extends beyond the junction T between the upper end portion of the partition wall 15 and the guide portion 16. In the modified example in which the second screw portion 14 rotates in the same rotational direction as in FIG. 3B, the end point Q of the guide portion 16 is a partition wall as shown in FIG. It is assumed that the upper end portion of 15 and the guide portion 16 extend to the region N beyond the joint portion T.

  Subsequently, a modified example of the configuration of the guide unit 16 in the first embodiment will be described with reference to the top views of FIGS. 6 to 10 show planar configurations when the developing device 1 is viewed from above in the vertical direction. In the example of the developing device 1 according to FIGS. 6 to 10, it is assumed that the second screw portion 14 rotates in the same rotation direction as that in FIG.

  Moreover, in the example of FIGS. 6-10, since the 2nd screw part 14 is rotating in the same rotation direction as FIG. 3 (A), the end point Q of the guide part 16 was shown to FIG. 3 (A). As described above, it is assumed that the upper end portion of the partition wall 15 and the guide portion 16 are extended to the region M beyond the joint portion T. In the modified example in which the second screw portion 14 rotates in the same rotational direction as in FIG. 3B, the end point Q of the guide portion 16 is a partition wall as shown in FIG. It is assumed that the upper end portion of 15 and the guide portion 16 extend to the region N beyond the joint portion T.

  In the example of FIG. 6, unlike the example of FIG. 5, a part of the guide portion 16 is missing in the middle of the developer conveyance direction of the stirring chamber 12. Specifically, the guide unit 16 is located downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12 and immediately downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12. 4 pitches of the blade portion 14b of the two screw portion 14 are provided continuously. Further, after the guide portion 16 is partially cut away, the blade portions 14b of the second screw portion 14 are continuously provided for two pitches from the middle of the stirring chamber 12 in the developer conveying direction. That is, in the example of FIG. 6, the total length in the longitudinal direction of the guide portion 16 (the total length of the guide portions 16) on the downstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17 is the first. The length is 6 pitches of the blade portion 14b of the 2 screw portion 14.

  In the example of FIG. 7, unlike the example of FIG. 5, the guide portion 16 is not provided so as to face almost the entire developer coating region of the developing sleeve. Specifically, the guide unit 16 is located downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12 and immediately downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12. 6 pitches of the blade portion 14b of the two screw portion 14 are continuously provided.

  In the example of FIG. 8, unlike the example of FIG. 5, the guide portion 16 is not provided so as to face almost the entire developer coating region of the developing sleeve. In the example of FIG. 8, unlike the example of FIG. 5, the toner replenishing port 17 in the stirring chamber 12 in the developer transport direction is downstream of the toner replenishing port 17 in the developer transport direction. The guide portion 16 is not provided from directly downstream. Specifically, the guide portion 16 is located downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12 and from the middle of the developer transport direction of the stirring chamber 12 to the blades of the second screw portion 14. The portion 14b is provided continuously for 6 pitches.

  In the example of FIGS. 9 and 10, unlike the examples of FIGS. 5 to 8, the toner replenishing port 17 is provided in the middle of the stirring chamber 12 in the developer conveying direction.

  In the example of FIG. 9, the guide portion 16 is provided so as to face almost the entire developer coating region of the developing sleeve. On the other hand, in the example of FIG. 10, unlike the example of FIG. 9, the guide portion 16 is not provided so as to face almost the entire developer coating region of the developing sleeve. 9 and 10, the guide unit 16 is located downstream of the toner supply port 17 in the developer transport direction of the stirring chamber 12 and directly behind the toner supply port 17 in the developer transport direction of the stirring chamber 12. From the downstream, 6 pitches of the blade portion 14b of the second screw portion 14 are continuously provided.

  Next, the configuration of the guide unit 16 according to the comparative example will be described with reference to the top view of FIG. FIG. 11 shows a planar configuration when the developing device is viewed from above in the vertical direction. In the example of the developing device according to FIG. 11, it is assumed that the second screw portion 14 rotates in the same rotation direction as that in FIG.

  In the example of FIG. 11, the toner replenishing port 17 is provided in the middle of the stirring chamber 12 in the developer transport direction. In the example of FIG. 11, the guide portion 16 is not provided so as to face almost the entire developer coating region of the developing sleeve.

  In the example of FIG. 11, the guide portion 16 is continuously provided at four pitches of the blade portion 14 b of the second screw portion 14 on the upstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17. . However, in the example of FIG. 11, the guide portion 16 is not provided downstream of the toner supply port 17 in the developer conveyance direction of the stirring chamber 12. Therefore, in the example of FIG. 11, the developer that has been slid down on the inclined surface of the guide portion 16 due to gravity cannot collide with the toner (upslip toner) supplied from the toner supply port 17. . Therefore, in the example of FIG. 11, the lump of the upslip toner is not loosened, so that it is not possible to expect the effect of improving the stirring property between the toner supplied from the toner supply unit and the developer in the stirring chamber 12.

  As described above, the first embodiment, which is an example of the present invention, has the following characteristics. That is, the continuous length in the longitudinal direction of the guide portion 16 continues at least two pitches or more of the blade portion 14b of the second screw portion 14 on the downstream side of the stirring chamber 12 in the developer transport direction from the toner supply port 17. It was a length. In addition, when the second screw portion 14 is rotating in the same rotational direction as in FIG. 3A, the end point Q of the guide portion 16 is the same as the upper end portion of the partition wall 15 as shown in FIG. It extended to the area | region M beyond the junction part T with the guide part 16. FIG.

  On the other hand, when the second screw portion 14 is rotating in the same rotational direction as that in FIG. 3B, the end point Q of the guide portion 16 is the same as the upper end portion of the partition wall 15 as shown in FIG. It extended to the area | region N beyond the junction part T with the guide part 16. FIG.

  As a result, the developed developer that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the guide portion 16 slides down on the inclined surface of the guide portion 16 due to gravity, and the toner The toner can be made to collide with toner (upslip toner) supplied from the supply port 17. Then, the lump of the top-sliding toner is loosened, and the surface area where the top-sliding toner comes into contact with the developer conveying surface of the blade portion 14b of the second screw portion 14 is increased. Stirability with the developer inside increases. Therefore, in the function separation type developing device, even if the height of the developer surface on the upstream side in the developer conveying direction of the stirring chamber is low, the toner is replenished from the toner replenishing portion with a simple configuration. The stirrability of the toner can be improved.

[Second Embodiment]
The structure of the guide part 16 in 2nd Embodiment is demonstrated using the top view of FIG. FIG. 12 shows a planar configuration when the developing device 1 is viewed from above in the vertical direction. In the example of the developing device 1 according to FIG. 12, it is assumed that the second screw portion 14 is rotating in the same rotation direction as that in FIG. 12, the same reference numerals as those in FIG. 5 denote the same constituent members.

  In the example of FIG. 12, as in the example of FIG. 5, the guide portion 16 is provided so as to face substantially the entire developer coating region of the developing sleeve. However, in the second embodiment, the configuration of the guide unit 16 is different from that in the first embodiment.

  Specifically, the first guide portion 16a that constitutes the guide portion 16 is continuously provided for 6 pitches of the blade portion 14b of the second screw portion 14 from directly downstream of the toner supply port 17 in the developer conveying direction of the stirring chamber 12. Is provided. Further, from the middle of the developer conveyance direction of the stirring chamber 12 (directly downstream of the first guide portion 16a in the developer conveyance direction of the stirring chamber 12), the second guide portion 16b constituting the guide portion 16 is a second screw portion. Two 14 pitch portions 14b are provided continuously.

  Since the second screw portion 14 is rotating in the same rotational direction as in FIG. 3A, the first guide portion 16a sets the end point Q of the guide portion 16 to the partition wall as shown in FIG. 15 is extended to the region M beyond the joint portion T between the upper end portion 15 and the guide portion 16. On the other hand, although the 2nd screw part 14 is rotating in the same rotation direction as FIG. 3 (A), the 2nd guide part 16b is the end point Q of the guide part 16 as shown in FIG.3 (B). In addition, it extends to the region N beyond the joint T between the upper end portion of the partition wall 15 and the guide portion 16. That is, the second embodiment is characterized in that the guide portion 16 is constituted by the first guide portion 16a and the second guide portion 16b.

  In the second embodiment, by having the first guide portion 16a, the developer after development that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the first guide portion 16a. Then, it slides down on the inclined surface of the first guide portion 16a by gravity and falls into the region M. As a result, similarly to the first embodiment, the developer after development can collide with the upslip toner existing on the developer surface over the entire region M. Then, the surface area of the upper sliding toner coming into contact with the developer conveying surface of the blade portion 14b of the second screw portion 14 is increased by loosening the lump of the upper sliding toner, so that the toner replenished from the toner replenishing port 17 and the stirring chamber The stirrability with the developer in 12 can be enhanced.

  Further, in the second embodiment, by having the second guide portion 16b, development after development that has been peeled off from the surface of the developing sleeve 3 in the developer peeling region and dropped onto the inclined surface of the second guide portion 16b. The agent is slid down on the inclined surface of the second guide portion 16 b by gravity and dropped into the region N.

  When the developer after development falls to the downstream side in the developer transport direction of the stirring chamber 12 through the guide portion 16, the second communication port (stirring chamber) from the developer dropping position in the developer transport direction of the stirring chamber 12 The section from 12 to the delivery chamber for delivering the developer to the developing chamber 11 is shortened. Therefore, the period during which the stirring force by the second screw portion 14 is received from when the developer after development is transported by the second screw portion 14 to the second communication port from the developer dropping position is shortened. Further, in the developer after development, since the toner is consumed in the development process, the toner concentration in the developer is low. Therefore, the developer after development is conveyed by the second screw part 14 and is stirred by the second screw part 14 until it reaches the second communication port from the position where the developer falls. It is desirable to make the period of stirring with the developer in the chamber 12 as long as possible.

  In the second embodiment, by having the second guide portion 16b on the downstream side in the developer transport direction of the stirring chamber 12, the developed developer that has dropped on the inclined surface of the second guide portion 16b Without falling to the region N (that is, the side farther from the second communication port). Thereby, the developer after the development is conveyed by the second screw part 14 and the developer after the development is reached by the second screw part 14 until it reaches the second communication port from the developer dropping position. A period of stirring with the developer in the stirring chamber 12 can be earned.

(Other embodiments)
The present invention is not limited to the above embodiment, and various modifications (including organic combinations of the embodiments) are possible based on the spirit of the present invention, and these are excluded from the scope of the present invention. is not.

  In the above embodiment, as shown in FIG. 2, the developing sleeve 3 rotates in the direction of the arrow R <b> 3 (counterclockwise), and the regulating blade 5 is disposed below the developing sleeve 3. Although the separation type developing device has been described as an example, the present invention is not limited to this. The present invention is applied to a function-separated type developing device in which the developing sleeve 3 rotates in the direction opposite to the direction of the arrow R3 (clockwise), and the regulating blade 5 is disposed above the developing sleeve 3. It is also possible to do.

  In the above-described embodiment, the example in which the toner weight ratio with respect to the developer weight replenished from the toner replenishing unit is 100% has been described, but the present invention is not limited thereto. This is a configuration of the developing device provided with a developer discharge port as a developer discharge portion for discharging a part of the developer circulating between the stirring chamber 12 and the developing chamber 11 from the developing container 2. And Then, a toner mixed with a small amount of magnetic carrier (for example, a toner whose weight ratio to the developer weight is 90% and whose magnetic carrier weight ratio to the developer weight is 10%) is replenished. Even if it is a structure, the same effect is acquired by this invention.

DESCRIPTION OF SYMBOLS 1 Developing device 3 Developing sleeve 11 Developing chamber 12 Stirring chamber 13 First screw portion 14 Second screw portion 14a Rotating shaft 14b Blade portion 15 Partition 16 Guide portion 17 Toner supply port

Claims (7)

A developer carrying member rotatably provided and carrying a developer containing toner and a magnetic carrier;
A supply chamber that is disposed below the developer carrying member with respect to the direction of gravity and that supplies the developer to the developer carrying member;
A recovery chamber disposed opposite to the developer carrying member and collecting the developer from the developer carrying member;
A first screw part disposed in the supply chamber and transporting the developer in the supply chamber in a first direction;
A rotation shaft disposed in the collection chamber and rotatable; and a spiral blade provided on an outer periphery of the rotation shaft; and a developer in the collection chamber in a direction opposite to the first direction. A second screw part for conveying in the direction;
A partition for guiding the developer from the developer carrying member to be collected in the collection chamber, and a partition wall separating the supply chamber and the collection chamber;
A toner replenishing unit disposed in the collection chamber for replenishing toner to a circulation path through which the developer circulates between the supply chamber and the collection chamber;
In a developing device comprising:
When the developing device is mounted on an image forming apparatus that forms an image on a recording material, the second screw portion rotates from a direction toward the partition to a direction downward in the vertical direction of the recovery chamber,
When viewed in a cross-section perpendicular to the rotation axis of the second screw part, one end of the guide part is disposed close to the developer carrier, and the other end of the guide part is the second screw. Arranged in the vertical direction above the region of the second screw part on the side closer to the partition from the rotation center of the part,
The developing device according to claim 1, wherein the guide portion is continuously provided at least two pitches of the blade portion of the second screw portion on the downstream side of the toner replenishing portion in the second direction. The developing device includes:
A second guide for guiding the developer from the developer carrying member to be collected in the collection chamber further downstream of the guide in the second direction;
When viewed in a cross section orthogonal to the rotation axis of the second screw part, one end of the second guide part is disposed close to the developer carrier, and the other end of the second guide part is It is arrange | positioned in the vertical direction upper direction of the area | region of the said 2nd screw part in the near side wall facing the said partition of the said collection | recovery chamber from the rotation center of the said 2nd screw part. Development device. 3. The guide according to claim 1, wherein the guide portion is continuously provided at least four pitches of the blade portion of the second screw portion on the downstream side of the toner replenishment portion in the second direction. The developing device described. 4. The apparatus according to claim 1, wherein when the developing device is mounted on the image forming apparatus, the supply chamber and the collection chamber are arranged side by side in the horizontal direction. 5. Development device. A developer carrying member rotatably provided and carrying a developer containing toner and a magnetic carrier;
A supply chamber that is disposed below the developer carrying member with respect to the direction of gravity and that supplies the developer to the developer carrying member;
A recovery chamber disposed opposite to the developer carrying member and collecting the developer from the developer carrying member;
A first screw part disposed in the supply chamber and transporting the developer in the supply chamber in a first direction;
A rotation shaft disposed in the collection chamber and rotatable; and a spiral blade provided on an outer periphery of the rotation shaft; and a developer in the collection chamber in a direction opposite to the first direction. A second screw part for conveying in the direction;
A partition for guiding the developer from the developer carrying member to be collected in the collection chamber, and a partition wall separating the supply chamber and the collection chamber;
A toner replenishing unit disposed in the collection chamber for replenishing toner to a circulation path through which the developer circulates between the supply chamber and the collection chamber;
In a developing device comprising:
When the developing device is mounted on an image forming apparatus that forms an image on a recording material, the second screw portion rotates in a direction from the direction toward the partition to the upper side in the vertical direction of the collection chamber,
When viewed in a cross-section perpendicular to the rotation axis of the second screw part, one end of the guide part is disposed close to the developer carrier, and the other end of the guide part is the second screw. Arranged in the vertical direction above the region of the second screw part on the side close to the side wall facing the partition wall of the recovery chamber from the rotation center of the part,
The developing device according to claim 1, wherein the guide portion is continuously provided at least two pitches of the blade portion of the second screw portion on the downstream side of the toner replenishing portion in the second direction. The said guide part is provided continuously 4 pitches or more of the said blade | wing part of the said 2nd screw part in the downstream of the said 2nd direction rather than the said toner replenishment part. Development device. The developing device according to claim 5 or 6, wherein when the developing device is mounted on the image forming apparatus, the supply chamber and the collection chamber are arranged side by side in the horizontal direction.

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