JP2014228748A - Developing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of suppressing the occurrence of image defects such as reduction in image density and fogging by uniformizing the charge amount distribution of toner in a short time and to provide an image forming apparatus.SOLUTION: The developing device includes a developing container, a first stir conveyance member, a second stir conveyance member, a developer supply member, a replenishment port, and a supply part. The developing container is partitioned into a developer replenishment path, a first conveyance chamber, and a second conveyance chamber arranged substantially in parallel to each other. The supply part is formed between the developer replenishment path and the first conveyance chamber and supplies a developer from the developer replenishment path to the first conveyance chamber. The supply part is formed on the upstream side from the downstream side end of the developer replenishment path in a developer conveyance direction in the developer replenishment path and on the downstream side from the replenishment port. The developer supply member supplies the developer to the first conveyance chamber from a direction opposite to the developer conveyance direction in the first conveyance chamber through the supply part.

Description

  The present invention relates to a developing device mounted on an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and an image forming apparatus provided with the same, and more particularly to a method for suppressing a decrease in density, fogging, and the like during toner replenishment. .

  Conventionally, as a development method using dry toner in an image forming apparatus using an electrophotographic process, a one-component development method using no carrier and a two-component developer charging a nonmagnetic toner using a magnetic carrier are used. In addition, a two-component development method is known in which an electrostatic latent image on an image carrier (photoconductor) is developed by a magnetic brush composed of toner and a carrier formed on a developing roller.

  In the developing device as described above, the toner is consumed by the developing operation. Therefore, a toner sensor for detecting the toner density (or toner amount) is provided in the developing device, and new toner is replenished by the amount consumed by the development.

  By the way, when the developing device is driven for a long time with a small amount of replenishing toner, such as when an image with a low printing rate is continuously printed or when an intermittent printing operation is repeated, the inside of the developing device is The mechanical stress experienced by the circulating toner increases. As a result, the charge amount of the toner in the developing device increases.

  If printing with a high printing rate or continuous printing is performed in this state, the initial toner having a relatively low charge amount is supplied into the developing device in a short time, and therefore, toner having a broad charge amount distribution is supplied to the developing roller. Image defects such as a decrease in image density and fogging occur.

  In view of this, a method for appropriately charging the replenishment toner has been proposed. For example, Patent Document 1 discloses a replenishment fog that stabilizes toner charging by installing a separating member and a preliminary charging roller in the stirring unit of the developing device. There has been disclosed a developing device which suppresses the above.

  Patent Document 2 discloses a toner installed in a collection conveyance path in a developing device that is disposed substantially horizontally in the order of a supply conveyance path, an agitation conveyance path, and a collection conveyance path from the vicinity of a developer regulating member. A configuration is disclosed in which toner and carrier are replenished from a replenishment position, and the collected developer containing the replenished toner and carrier is merged into the agitation transport path from the downstream end of the recovery transport path.

JP 2006-11226 A JP 2007-147806 A

  However, the developing device of Patent Document 1 has a complicated structure and cannot be increased in size. In addition, since the deteriorated toner stays in the separation member and the preliminary charging member, it is difficult to stabilize the charging of the toner for a long time.

  In the developing device disclosed in Patent Document 2, the developer in the collection conveyance path is once blocked at the downstream end of the collection conveyance path, and then substantially perpendicular to the developer flow circulating in the stirring conveyance path. It will merge from the direction. For this reason, the collected developer containing the replenished toner and carrier and the developer circulating in the stirring conveyance path cannot be sufficiently stirred and mixed at the junction, and the charge amount distribution of the toner circulating in the developing device There was a risk of variation.

  In view of the above problems, the present invention provides a developing device capable of suppressing the occurrence of image defects such as a decrease in image density and fog by uniformizing the toner charge amount distribution in a short time, and an image forming apparatus including the same. The purpose is to provide.

  In order to achieve the above object, a first configuration of the present invention includes a developing container, a first agitation transport member, a second agitation transport member, a developer supply member, a replenishing port, and a supply unit. Development device. The developer container is divided into a developer supply passage, a first transfer chamber, and a second transfer chamber that are arranged substantially in parallel with each other, and stores a developer containing toner. The first agitating and conveying member agitates and conveys the developer in the first conveying chamber. The second agitating and conveying member agitates and conveys the developer in the second conveying chamber in the opposite direction to the first agitating and conveying member. The developer supply member supplies the developer in the developer supply passage to the first transport chamber. The supply port is formed in the developer supply passage and is connected to the developer supply mechanism. The supply unit is formed between the developer supply passage and the first transfer chamber, and supplies the developer from the developer supply passage to the first transfer chamber. The supply unit is formed upstream of the downstream end of the developer supply passage and downstream of the supply port with respect to the developer transport direction in the developer supply passage. The developer is supplied to the first transfer chamber from the direction opposite to the developer transfer direction in the first transfer chamber via the section.

  According to the first configuration of the present invention, the replenishment toner transported in the developer replenishment passage and the circulating toner transported in the first transport chamber collide in the vicinity of the supply unit from opposite directions, and the inside of the first transport chamber A part of the circulating toner is taken into the developer supply passage from the supply unit, and is stirred together with the supply toner. As a result, the replenishment toner in the developer replenishment passage and the circulating toner in the first transport chamber are sufficiently agitated and mixed in the supply unit, so that the toner charge amount distribution in the developer container can be made uniform in a short time. it can. Accordingly, it is possible to suppress problems such as a decrease in image density due to toner overcharging and image fogging due to insufficient toner charging.

1 is a schematic cross-sectional view illustrating an overall configuration of an image forming apparatus 100 including a developing device 4 according to an embodiment of the present invention. Side surface sectional view showing the structure of the developing device 4 of the present embodiment External appearance perspective view which shows the state which removed the cover member 42 of the image development apparatus 4 of this embodiment. Plan sectional drawing which shows the structure of the stirring part of the image development apparatus 4 of this embodiment. The perspective view which shows the structure of the 1st spiral 31 used for the image development apparatus 4 of this embodiment. External perspective view of the developing device 4 of the present embodiment The perspective view which shows the structure of the developer supply member 35 used for the image development apparatus 4 of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the structure of an image forming apparatus 100 including a developing device 4 according to an embodiment of the present invention. In an image forming apparatus (for example, a monochrome printer) 100, when an image forming operation is performed, an electrostatic latent image based on document image data transmitted from a personal computer (PC) (not shown) is generated in an image forming unit P in the apparatus main body. The toner is attached to the electrostatic latent image by the developing device 4 to form a toner image. The toner is supplied to the developing device 4 from the toner container 5. In such an image forming apparatus 100, an image forming process is performed on the photosensitive drum 1 while rotating the photosensitive drum 1 in the clockwise direction in FIG.

  The image forming unit P includes a charging unit 2, an exposure unit 3, a developing device 4, a transfer roller 6, a cleaning device 7, and a charge eliminating device (not shown) along the rotation direction (clockwise direction) of the photosensitive drum 1. ) Is arranged. The photosensitive drum 1 is formed, for example, by laminating a photosensitive layer on an aluminum drum, and the charging unit 2 charges the surface. Then, an electrostatic latent image in which charging is attenuated is formed on the surface that has received a laser beam from the exposure unit 3 described later. The photosensitive layer is not particularly limited. For example, amorphous silicon (a-Si) having excellent durability, or an organic photosensitive layer (OPC) that generates high-resolution images with little generation of ozone during charging. Etc.) are preferred.

  The charging unit 2 uniformly charges the surface of the photosensitive drum 1. For example, a corona discharge device that discharges by applying a high voltage using a thin wire or the like as an electrode is used as the charging unit 2. Instead of the corona discharge device, a contact-type charging device that applies a voltage in a state where a charging member typified by a charging roller is in contact with the surface of the photoreceptor may be used. The exposure unit 3 irradiates the photosensitive drum 1 with a light beam (for example, a laser beam) based on the image data, and forms an electrostatic latent image on the surface of the photosensitive drum 1.

  The developing device 4 forms toner images by attaching toner to the electrostatic latent image on the photosensitive drum 1. Here, a magnetic one-component developer (hereinafter also simply referred to as toner) composed only of a magnetic toner component is accommodated in the developing device 4. Details of the developing device 4 will be described later. The transfer roller 6 transfers the toner image formed on the surface of the photosensitive drum 1 to the sheet conveyed through the sheet conveyance path 11 without disturbing the toner image. The cleaning device 7 includes a cleaning roller and a blade material that are in line contact with the longitudinal direction of the photosensitive drum 1, and removes residual toner remaining on the surface of the photosensitive drum 1 after the toner image is transferred to the paper. To do.

  Then, the exposure unit 3 emits a laser beam (light beam) on the photosensitive drum 1 based on image data inputted in advance, thereby forming an electrostatic latent image based on the image data on the surface of the photosensitive drum 1. Thereafter, the developing device 4 attaches toner to the electrostatic latent image to form a toner image.

  A sheet is conveyed from the sheet storage unit 10 through the sheet conveyance path 11 and the registration roller pair 13 at a predetermined timing toward the image forming unit P on which the toner image is formed as described above. The toner image on the surface of the photosensitive drum 1 is transferred to a sheet by the transfer roller 6. The sheet on which the toner image has been transferred is separated from the photosensitive drum 1, conveyed to the fixing unit 8, and heated and pressurized to fix the toner image on the sheet. The paper that has passed through the fixing unit 8 passes through the discharge roller pair 14 and is discharged to the paper discharge unit 15.

  FIG. 2 is a side sectional view showing the structure of the developing device 4. The detailed structure of the developing device 4 will be described with reference to FIG. 2 shows a state as viewed from the back side of FIG. 1, and the arrangement of each member in the developing device 4 is opposite to that in FIG.

  As shown in FIG. 2, the developing device 4 includes a developing roller (developer carrying member) 20, a regulating blade 21, a stirring and conveying member 30, a developer supplying member 35, a developing container 40 that accommodates these members, and the like. , Is configured.

  The developing container 40 constitutes the outline of the developing device 4, and includes a main body 41 and a cover member 42 that covers an upper portion of the developer supply member 35 and the like. The developing container 40 is partitioned into a first transfer chamber 40a and a second transfer chamber 40b by a partition portion 41a formed in the main body portion 41. The first transfer chamber 40a and the second transfer chamber 40b contain a one-component developer made of toner. Further, the developing container 40 rotatably holds the stirring and conveying member 30, the developer supply member 35, and the developing roller 20. Further, the developing container 40 is formed with an opening 40c that exposes the developing roller 20 toward the photosensitive drum 1 (see FIG. 1).

  The developing roller 20 is disposed to face the photosensitive drum 1 with a certain interval. Further, the developing roller 20 supplies toner to the photosensitive drum 1 in a facing area close to the photosensitive drum 1. The agitating / conveying member 30 is disposed diagonally to the left of the developing roller 20. The regulating blade 21 is fixedly held in the developing container 40 on the left side of the developing roller 20.

  The agitating / conveying member 30 is composed of a first spiral (first agitating / conveying member) 31 and a second spiral (second agitating / conveying member) 32. The second spiral 32 is provided in the second transfer chamber 40b diagonally to the left of the developing roller 20, and the first spiral 31 is provided in the first transfer chamber 40a adjacent to the left side of the second spiral 32. .

  The first and second spirals 31 and 32 convey the developer while stirring. Further, at both end portions in the longitudinal direction (direction perpendicular to the paper surface of FIG. 2) of the partition portion 41a that partitions the first transfer chamber 40a and the second transfer chamber 40b, there are communication portions (an upstream communication portion 40d and a downstream side described later). When the first spiral 31 rotates, the developer is transported to the second spiral 32 from one communicating portion provided in the partition 41a, and the developer is brought into the first transport chamber 40a. It circulates in the second transfer chamber 40b. Then, the developer is supplied from the second spiral 32 to the developing roller 20.

  The developing roller 20 includes a fixed shaft 20a, a magnetic pole member 20b, a developing sleeve 20c formed in a cylindrical shape with a nonmagnetic metal material, and the like. The developing roller 20 is rotated in the counterclockwise direction of FIG. 2 by a driving mechanism including a motor and a gear (not shown).

  When the developing sleeve 20c to which the developing bias is applied rotates, the developing sleeve is developed due to a potential difference between the developing bias potential and the exposed portion of the photosensitive drum 1 in the developing region (the region where the developing roller 20 and the photosensitive drum 1 face each other). The toner carried on the surface 20c flies to the photosensitive drum 1. The flying toner sequentially adheres to the exposed portion on the rotating photosensitive drum 1, and the electrostatic latent image on the photosensitive drum 1 is developed.

  FIG. 3 is an external perspective view showing a state in which the cover member 42 of the developing device 4 is removed, and FIG. 4 is a plan sectional view showing the structure of the stirring unit of the developing device 4. As shown in FIGS. 3 and 4, the developing container 40 is formed with a partition 41a, a first transfer chamber 40a, a second transfer chamber 40b, and communication portions 40d and 40e. A supply passage 40f is formed. The developer replenishment passage 40f is a passage for replenishing new developer (replenishment toner) from the toner container 5 to the first transfer chamber 40a.

  The first transfer chamber 40a, the second transfer chamber 40b, and the developer supply passage 40f are arranged in parallel with each other. A partition 41a extending in the longitudinal direction of the developing container 40 is provided so as to partition the first transport chamber 40a and the second transport chamber 40b, and development is performed so as to partition the developer supply passage 40f and the first transport chamber 40a. A partition 41b extending in the longitudinal direction of the container 40 is provided. In the first transfer chamber 40a, the left side in FIG. 3 is the upstream side, the right side in FIG. 3 is the downstream side, and in the second transfer chamber 40b, the right side in FIG. 3 is the upstream side, and the left side in FIG. And

  The communication portions 40d and 40e are formed on one side and the other side (A1 direction side and A2 direction side) in the longitudinal direction of the partition portion 41a, respectively. The communication portion 40d communicates the end portions in the A1 direction of the first transfer chamber 40a and the second transfer chamber 40b. The communication unit 40e communicates the end portions in the A2 direction of the first transfer chamber 40a and the second transfer chamber 40b. The developer can circulate in the first transfer chamber 40a, the communication portion 40d, the second transfer chamber 40b, and the communication portion 40e.

  FIG. 5 is a perspective view showing the structure of the first spiral 31 used in the developing device 4. As shown in FIGS. 3 to 5, the first spiral 31 is provided integrally with the rotary shaft 31 a and the rotary shaft 31 a, and is formed in a spiral shape at a constant pitch in the axial direction of the rotary shaft 31 a. And a blade (blade) 31b. The rotating shaft 31a is rotatably supported by the developing container 40. The first spiral blade 31b transports the developer in the first transport chamber 40a in the A1 direction while stirring.

  The second spiral 32 has the same structure as the first spiral 31 shown in FIG. 5 except that the direction (phase) of the spiral blades is different. That is, the second spiral 32 is provided integrally with the rotary shaft 32a and the rotary shaft 32a, and faces the opposite direction to the first spiral blade 31b at the same pitch as the first spiral blade 31b in the axial direction of the rotary shaft 32a ( And a second spiral blade 32b formed in a spiral shape with blades of opposite phase. The rotation shaft 32a is disposed in parallel with the rotation shaft 31a and is rotatably supported by the developing container 40. The second spiral blade 32b supplies the developer to the developing roller 20 while stirring and transporting the developer in the second transport chamber 40b in the A2 direction (the direction opposite to the A1 direction).

  As shown in FIG. 6, at the portion of the developer supply passage 40f on the A1 side, a supply port 42a for supplying new developer into the developer container 40 from the toner container 5 provided above the developer container 40 is provided. The cover member 42 is formed. A toner sensor (not shown) for detecting the amount of toner in the developing container 40 is installed on the inner wall of the first transfer chamber 40a or the second transfer chamber 40b, and a toner container is detected according to the detection result of the toner sensor. The toner (developer) stored in 5 (see FIG. 1) is supplied into the developing container 40 through the supply port 42a.

The developer supply passage 40f is a passage for conveying the developer supplied to the portion on the A1 direction side in the A2 direction and supplying it to the upstream side of the first transfer chamber 40a. In the developer supply passage 40f, a supply portion 40g for supplying the developer from the developer supply passage 40f to the first transfer chamber 40a is formed. The supply section 40g is upstream (right side in FIG. 4) upstream from the downstream end (left end in FIG. 4) of the developer supply path 40f with respect to the developer transport direction (A2 direction) in the developer supply path 40f. Further, it is formed on the downstream side (left side in FIG. 4) from the supply port 42a.

  A developer supply member 35 is disposed in parallel to the first spiral 31 and the second spiral 32 in the developer supply passage 40f. As shown in FIGS. 3 and 7, the developer supply member 35 has a rotation shaft 35a, and a third spiral blade 35b and a fourth spiral blade 35c provided integrally with the rotation shaft 35a. The third spiral blade 35b is formed in a spiral shape with a blade facing in the opposite direction to the first spiral blade 31b in the axial direction of the rotation shaft 35a (in reverse phase), and is supplied from the supply port 42a (see FIG. 6). Part 40g is formed. The fourth spiral blade 35c is formed in a spiral shape with blades facing in the opposite direction (in reverse phase) from the third spiral blade 35b, and is formed from the supply unit 40g to the end portion on the A2 direction side. A paddle-shaped conveying blade 35d is formed in a portion of the rotating shaft 35a facing the supply unit 40g.

  The developer supply member 35 is configured to rotate in the same direction as the first spiral 31 (counterclockwise in FIG. 2), and the developer supplied to the supply port 42a is conveyed to the supply unit 40g side. . Since the third spiral blade 35b and the fourth spiral blade 35c have phases opposite to each other, the developer collides at the supply unit 40g by the third spiral blade 35b and the fourth spiral blade 35c, and the first transfer chamber 40a. It is conveyed to.

  Each of the developer supply member 35, the first spiral 31, and the second spiral 32 is rotationally driven by a driving mechanism including a motor and a gear (not shown).

  As shown in FIG. 2, the developer supply member 35 rotates in the counterclockwise direction to supply the developer to the first spiral 31 from below. Further, a rib 42b extending downward (upstream in the rotation direction of the developer supply member 35) is formed in the upper part of the supply unit 40g (a portion of the supply unit 40g on the downstream side in the rotation direction of the developer supply member 35). Has been. The side surface 42c on the first spiral 31 side of the rib 42b is formed by a plane extending in the vertical direction. The ribs 42b are formed in substantially the entire region in the width direction (A1, A2 direction) of the supply unit 40g. Further, the rib 42b is integrally formed with the cover member 42 by resin.

  As shown in FIGS. 2 and 4, the supply unit 40g is an opening having a predetermined opening width in the horizontal direction (left-right direction in FIG. 4) and the vertical direction (up-down direction in FIG. 2). When the opening width in the vertical direction is smaller than the outer diameter of the developer supply member 35 (the diameters of the third spiral blade 35b and the fourth spiral blade 35c), the toner supply capability is insufficient. On the other hand, when the opening width in the vertical direction is larger than the outer diameter of the developer supply member 35, the toner flows backward from the first transfer chamber 40a to the developer supply passage 40f. Therefore, the opening width in the vertical direction is formed to be substantially equal to the outer diameter of the developer supply member 35.

  In the present embodiment, as described above, the toner (developer) replenished from the replenishing port 42a into the developer replenishing passage 40f is conveyed in the developer replenishing passage 40f in the A2 direction (as indicated by the broken line arrow in FIG. 4). display). On the other hand, the toner in the first transfer chamber 40a is transferred in the A1 direction (indicated by a solid line arrow in FIG. 4). The toner in the developer supply passage 40f conveyed in the A2 direction merges with the circulating toner in the first conveyance chamber 40a conveyed in the A1 direction in the supply unit 40g.

  Thus, when the replenishment toner in the developer replenishment passage 40f is sent into the first transport chamber 40a, the replenishment toner transported in the developer replenishment passage 40f in the A2 direction and the interior of the first transport chamber 40a in the A1 direction. The conveyed circulating toner collides in the vicinity of the supply unit 40g, and a part of the circulating toner in the first conveyance chamber 40a is taken into the developer supply passage 40f from the supply unit 40g and stirred together with the supplied toner. As a result, the replenishment toner in the developer replenishment passage 40f and the circulating toner in the first transfer chamber 40a are sufficiently agitated and mixed in the supply unit 40g, so that the toner charge amount distribution in the developer container 40 can be reduced in a short time. It can be made uniform. Accordingly, it is possible to suppress problems such as a decrease in image density due to toner overcharging and image fogging due to insufficient toner charging.

  Here, the supply section 40g is formed closer to the upstream side than the end in the transport direction downstream side (A2 direction side) of the developer supply path 40f, and the developer supply path 40f is downstream in the transport direction from the supply section 40g. It extends to. And between the supply part 40g and the edge part of the A2 direction side, the 4th spiral blade 35c which turns to a reverse direction (the reverse phase) with respect to the 3rd spiral blade 35b is formed. As a result, toner convection by the fourth spiral blade 35c occurs in the vicinity of the supply unit 40g. Therefore, the toner in the vicinity of the supply unit 40g where the replenishment toner and the circulating toner are mixed can be stirred more efficiently.

  The supply unit 40g is formed on the downstream side of the first transfer chamber 40a with respect to the upstream communication unit 40e with respect to the developer transfer direction (A1 direction) in the first transfer chamber 40a. With this configuration, the circulating toner in the first transfer chamber 40a and the replenishing toner in the developer replenishing passage 40f can collide with each other in the opposite direction at the supply unit 40g, and the recirculating toner and the replenishing toner are sufficiently mixed with stirring. The

  If the supply unit 40g is formed in the vicinity of the replenishing port 42a, uncharged toner that has been replenished from the replenishing port 42a is immediately supplied into the first transfer chamber 40a, which is caused by insufficient charging of the toner. Image fog may occur. Therefore, in order to keep the supply port 42a and the supply unit 40g as far as possible from each other, the supply port 42a is formed at the upstream end (right side in FIG. 6) in the transport direction of the developer supply passage 40f as in the present embodiment. The supply section 40g is preferably formed closer to the downstream side in the transport direction (left side in FIG. 6) than the central portion of the developer supply passage 40f.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, the first spiral 31 and the second spiral 32 in which the spiral blades 31b and 32b are continuously provided around the rotation shafts 31a and 31b are used. However, the embodiment is limited to the spiral blades 31b and 32b. Alternatively, for example, a stirring and conveying member in which a plurality of half-moon shaped plates (a circular plate divided into two) is alternately arranged around the rotation shafts 31a and 32a at a predetermined inclination angle may be used.

  In the above embodiment, an example in which a one-component developer composed only of toner is used as a developer has been described. However, the present invention is not limited to this, and a two-component developer composed of carrier and toner may be used as a developer. Good.

  In the above embodiment, the example in which the developer supply member rotates so as to supply the developer to the first stirring and conveying member from the lower side is shown. However, the present invention is not limited to this, and the developer supply member is The developer may be rotated so that the developer is supplied to the one agitation transport member from above.

  Further, in the above embodiment, the present invention is not limited to the monochrome printer shown in FIG. 1, but the first stirring and conveying member, the second stirring, such as a digital or analog monochrome copying machine, a color printer, a color copying machine, and a facsimile. The present invention can be applied to various image forming apparatuses including a developing device including a conveying member and a developer supply member.

  The present invention is applicable to a developing device including a developer supply passage, a first transfer chamber, and a second transfer chamber that are arranged substantially in parallel with each other. By utilizing the present invention, the toner charge amount distribution can be made uniform in a short time, and the developing device can suppress the occurrence of image defects such as a decrease in image density and fog.

4 Developing device 5 Toner container (developer supply mechanism)
31 1st spiral (1st stirring conveyance member)
32 2nd spiral (2nd stirring conveyance member)
35 Developer supply member 35a Rotating shaft 35b Third spiral blade 35c Fourth spiral blade 40 Developer container 40a First transport chamber 40b Second transport chamber 40d, 40e Communication portion 40f Developer supply passage 40g Supply portion 42 Cover member 100 Image formation apparatus

Claims (6)

A developer container containing a developer containing toner, which is partitioned into a developer supply passage, a first transfer chamber, and a second transfer chamber, which are arranged substantially in parallel with each other;
A first agitating and conveying member for agitating and conveying the developer in the first conveying chamber;
A second agitating and conveying member for agitating and conveying the developer in the second conveying chamber in a direction opposite to the first agitating and conveying member;
A developer supply member for supplying the developer in the developer supply passage to the first transfer chamber;
A replenishment port formed in the developer replenishment passage and connected to a developer replenishment mechanism;
In a developing device comprising:
A supply section for supplying developer from the developer supply passage to the first transfer chamber is provided between the developer supply passage and the first transfer chamber. Formed upstream of the downstream end of the developer supply passage with respect to the direction and downstream of the supply port.
The developing device, wherein the developer supply member supplies the developer to the first transfer chamber from the direction opposite to the developer transfer direction in the first transfer chamber via the supply unit.   Two communication portions are formed to communicate the both ends of the first transfer chamber and the second transfer chamber, and the supply portion communicates upstream of the developer transfer direction in the first transfer chamber. The developing device according to claim 1, wherein the developing device is formed on a downstream side of the first transfer chamber with respect to a portion.   The replenishing port is formed at an upstream end portion of the developer replenishment passage with respect to the developer transport direction in the developer replenishment passage, and the supply unit is configured to supply the developer in the developer replenishment passage. 3. The developing device according to claim 1, wherein the developing device is formed closer to a downstream side than a central portion of the developer supply passage with respect to a transport direction. The developer supply member is composed of a rotating shaft and a spiral blade formed on the outer peripheral surface of the rotating shaft,
The spiral blade formed between the supply portion and the downstream end portion of the developer supply passage is opposite to the spiral blade formed between the supply portion and the upstream end portion of the developer supply passage. The developing device according to claim 1, wherein the developing device is a phase.   The supply portion is an opening having a predetermined opening width in a horizontal direction and a vertical direction, and an opening width in a vertical direction of the supply portion is substantially equal to an outer diameter of the developer supply member. The developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.