JP2010128115A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device in which such a defect that density irregularities occur on an output image is reduced because toner is sufficiently stirred and mixed into developer in a developer circulation path and to provide a process cartridge and an image forming apparatus. <P>SOLUTION: The developing device includes: a first developer conveying part 53Y which supplies the developer to a developer carrier 51Y, while conveying the developer in the longitudinal direction by a first developer conveying means 55Y; and a second developer conveying part 54Y which conveys the developer sent in from the downstream side in the conveying direction of the first developer conveying part 53Y, in the longitudinal direction by second developer conveying means 56Y and 57Y, to send out the developer to the upstream side in the conveying direction of the first developer conveying part 53Y. The second developer conveying means are a plurality of screw-like rotating members 56Y and 57Y and disposed so that the position of the top of the screw part of at least one screw-like rotating member 57Y of the plurality of screw-like rotating members is deviated from the position of the top of the screw part of the other screw-like rotating member 56Y in the rotational axis direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using an electrophotographic method such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and a developing device and a process cartridge installed therein, and particularly uses a two-component developer. The present invention relates to a developing device, a process cartridge, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in a developing device in an image forming apparatus such as a copying machine or a printer, a plurality of developer conveying units in which a two-component developer composed of toner and a carrier (including cases where additives are added) are accommodated. There is known a technique in which a two-component developer is transported in the longitudinal direction and a circulation path is formed by a plurality of developer transport sections (see, for example, Patent Documents 1 to 4).

Specifically, the developing device is composed of a developing roller (developer carrying member), two developer conveying portions each provided with a screw-like rotating member such as a conveying screw or an auger, a doctor blade (developer regulating member), and the like. A two-component developer is accommodated in the interior.
Then, according to toner consumption in the developing device, toner is appropriately replenished into the device from a toner replenishing port provided at one end of the developing device. The replenished toner is mixed with the developer in the developing device while being circulated in the longitudinal direction (the same direction as the longitudinal direction of the developing roller) by the two screw-like rotating members. A part of the mixed developer is carried on a developing roller facing a first conveying screw installed in the first developer conveying unit. After the developer carried on the developing roller is regulated to an appropriate amount by a doctor blade, the toner in the developer adheres to the latent image on the photosensitive drum at a position facing the photosensitive drum (image carrier). .

  Further, in such a developing device, the replenishment toner tends to float on the upper surface (agent surface) of the developer without being sufficiently stirred and mixed in the developer in the developer circulation path (this phenomenon is There is a known problem that density unevenness due to toner charging failure occurs on an output image (refer to, for example, Patent Document 1 and Patent Document 2).

In order to solve such a problem, Patent Document 1 and the like disclose a technique for ejecting air from the upstream side of the toner supply port.
Patent Document 2 and the like disclose a technique for forming a partition wall around a conveying member (screw-shaped rotating member) in a cylindrical shape.
Patent Document 3 discloses a technique for forming a developer restraining region by installing a permanent magnet in the developer circulation path.
Japanese Patent Application Laid-Open No. H11-228561 discloses a technique for dropping the developer separated from the developing roller at the position of the doctor blade to the downstream side of the toner supply port.

JP 2008-26572 A JP 2006-106171 A JP 2006-58696 A JP 2006-58667 A

  In the conventional developing device described above, under various conditions, the toner is not sufficiently agitated and mixed in the developer in the developer circulation path, causing the toner to “slip”, resulting in uneven density on the output image. Could occur.

Specifically, in the technique of Patent Document 1 or the like, when the bulk density of the developer around the air ejection port varies depending on the image ratio of the output image, a change occurs in the agitation / mixing property of the developer by air. There was a possibility.
Further, in the techniques of Patent Document 2, Patent Document 3, and the like, there is a possibility that the toner is not sufficiently stirred and mixed in the developer unless the height of the developer surface is secured to some extent.
Furthermore, the technique disclosed in Patent Document 4 or the like causes the developer to drop from the developer on which the toner floats, and the toner may not be sufficiently stirred and mixed in the developer by itself.

  The present invention has been made to solve the above-described problems, and the toner is sufficiently agitated and mixed in the developer in the developer circulation path, thereby causing uneven density on the output image. Is to provide a developing device, a process cartridge, and an image forming apparatus.

  According to a first aspect of the present invention, there is provided a developing device for storing a developer having a carrier and a toner and developing a latent image formed on an image carrier, the image carrier. A developer carrying body that faces the body and carries the developer, and a first developer carrying unit that feeds the developer to the developer carrying body while carrying the developer in the longitudinal direction by the first developer carrying means And the first developer conveying portion so as to face the first developer conveying portion via a partition member, and the developer fed from the downstream side in the conveying direction of the first developer conveying portion is conveyed to the second developer. And a second developer conveying section that conveys in the longitudinal direction by the means and sends it to the upstream side of the first developer conveying section in the conveying direction, the first developer conveying means and the second developer conveying means At least one of them has a plurality of screw-shaped turns And at least one screw-shaped rotating member among the plurality of screw-shaped rotating members is configured such that a position of a top portion of the screw portion is a rotation axis direction with respect to a position of a top portion of the screw portion of another screw-shaped rotating member. It is arrange | positioned so that it may slip | deviate.

  A developing device according to a second aspect of the present invention is the developing device according to the first aspect, wherein the plurality of screw-shaped rotating members rotate in the same direction.

  According to a third aspect of the present invention, in the developing device according to the first aspect, the one screw-shaped rotating member rotates in a direction different from the rotational direction of the other screw-shaped rotating member. Is.

  A developing device according to a fourth aspect of the present invention is the developing device according to any one of the first to third aspects, further comprising a gear train that rotationally drives the plurality of screw-like rotating members. Can not be assembled when the position of the top of the screw part of the one screw-shaped rotating member is not arranged so as to be displaced in the rotational axis direction with respect to the position of the top of the screw part of the other screw-shaped rotating member. It is composed of.

  According to a fifth aspect of the present invention, there is provided the developing device according to the fourth aspect, wherein the gear train is engaged with a fitting portion formed on a shaft portion of a plurality of screw-shaped rotating members. A plurality of gears each having a notch formed in a part of a collar portion having a tooth surface and a plurality of gears are formed, and the plurality of gears are screw portions of the one screw-shaped rotating member. So that the flange portion interferes with other gear when the position of the top portion of the screw is not arranged so as to be displaced in the rotational axis direction with respect to the position of the top portion of the screw portion of the other screw-shaped rotating member. The position of the notch with respect to the joint is determined.

  The developing device according to a sixth aspect of the present invention is the developing device according to any one of the first to fifth aspects, wherein the one screw-shaped rotating member is a cross section perpendicular to the rotational axis direction. The screw portion and the screw portion of the other screw-like rotating member adjacent to each other are configured to alternately approach the other screw-like rotating member at different timings.

  The developing device according to a seventh aspect of the present invention is the developing device according to any one of the first to sixth aspects, wherein the plurality of screw-like rotating members have a screw pitch and a screw diameter of the screw portion. They are formed to be the same as each other and are driven to rotate at the same rotational speed.

  The developing device according to an eighth aspect of the present invention is the developing device according to any one of the first to seventh aspects, wherein the plurality of screw-shaped rotating members are disposed in the second developer conveying section. The first developer conveying means is a single screw-shaped rotating member, and the second developer conveying portion includes a toner replenishing port for replenishing toner on the upstream side in the conveying direction. is there.

  A process cartridge according to a ninth aspect of the present invention is a process cartridge that is detachably installed on the main body of the image forming apparatus, and the development according to any one of the first to eighth aspects. The apparatus and the image carrier are integrated.

  An image forming apparatus according to a tenth aspect of the present invention includes the developing device according to any one of the first to eighth aspects and the image carrier.

  In the present application, “process cartridge” means a charging unit (charging device) for charging an image carrier, a developing unit (developing device) for developing a latent image formed on the image carrier, and an image carrier. It is defined as a unit in which at least one of the cleaning unit (cleaning device) for cleaning the top and the image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

  In the present application, “toner” replenished from the toner replenishing port is toner newly replenished to the developing device, and in addition to new toner, recycled toner (for example, toner collected by the cleaning unit). In the case where the developing device is resupplied to the developing device).

  According to the present invention, at least one of a first developer transport unit installed in the first developer transport unit and a second developer transport unit installed in the second developer transport unit is rotated in a plurality of screw shapes. As a member, it is comprised so that the position of the top part of the screw part of at least 1 screw-shaped rotation member may shift | deviate to a rotating shaft direction with respect to the position of the top part of the screw part of another screw-shaped rotation member. As a result, the developing device, the process cartridge, and the image forming apparatus can alleviate the problem that the toner is sufficiently agitated and mixed in the developer in the developer circulation path to cause density unevenness on the output image. Can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described.
As shown in FIG. 1, four toner containers 32Y, 32M, 32C, and 32K corresponding to the respective colors (yellow, magenta, cyan, and black) are attached to and detached from the toner container accommodating portion 31 above the image forming apparatus main body 100. It is installed freely (changeable).
An intermediate transfer unit 15 is disposed below the toner container housing 31. Image forming portions 6Y, 6M, 6C, and 6K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 8 of the intermediate transfer unit 15.
Although illustration is omitted, toner replenishing devices are respectively disposed below the toner containers 32Y, 32M, 32C, and 32K. The toners stored in the toner containers 32Y, 32M, 32C, and 32K are respectively supplied (supplied) into the developing devices of the image forming units 6Y, 6M, 6C, and 6K by the toner replenishing device.

  Referring to FIG. 2, an image forming unit 6Y corresponding to yellow includes a photosensitive drum 1Y as an image carrier, a charging unit 4Y disposed around the photosensitive drum 1Y, and a developing device 5Y (developing unit). , A cleaning unit 2Y, a charge eliminating unit (not shown), and the like. Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1Y, and a yellow image is formed on the photosensitive drum 1Y.

  The other three image forming units 6M, 6C, and 6K have substantially the same configuration as that of the image forming unit 6Y corresponding to yellow except that the color of the toner used is different. A corresponding image is formed. Hereinafter, description of the other three image forming units 6M, 6C, and 6K will be omitted as appropriate, and only the image forming unit 6Y corresponding to yellow will be described.

Referring to FIG. 2, a photosensitive drum 1Y as an image carrier is rotationally driven in a clockwise direction in FIG. 2 by a drive motor (not shown). Then, the surface of the photosensitive drum 1Y is uniformly charged at the position of the charging unit 4Y (a charging process).
After that, the surface of the photosensitive drum 1Y reaches the irradiation position of the laser beam L emitted from the exposure device 7 (see FIG. 1), and the electrostatic latent image corresponding to yellow by exposure scanning at this position. Is formed (this is an exposure step).

Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the developing device 5Y, and the electrostatic latent image is developed at this position to form a yellow toner image (developing process).
Specifically, referring to FIGS. 2 and 3, a two-component developer G composed of toner and a carrier (magnetic carrier) is accommodated in the developing device 5Y. The developer G in the developing device 5Y is adjusted so that the toner concentration (the ratio of the toner in the developer G) detected by a magnetic sensor (not shown) is within a predetermined range. That is, according to the toner consumption in the developing device 5Y, the toner (replenishment toner) is replenished into the second developer transport portion 54Y by the toner replenishing device via the toner replenishing port 64Y.
The toner replenishing device is connected to the toner container 32Y. Although not shown, the toner replenishing device is stored in a driving unit that rotates and drives the toner container 32Y (toner bottle), a toner tank unit that stores toner discharged from the toner container 32Y, and a toner tank unit. A toner conveying section that conveys the toner toward the toner dropping path, and a toner dropping path that causes the toner conveyed by the toner conveying section to fall by its own weight toward the developing device 5Y (second developer conveying section 54Y). Has been.

  Referring to FIGS. 2 and 3, the toner (supplemented toner) replenished into the second developer transporting part 54Y through the toner replenishing port 64Y is then transferred to three transporting screws 55Y to 57Y (screw-like rotating members). ) Circulates between the first developer conveying portion 53Y and the second developer conveying portion 54Y separated by the partition member while being mixed and stirred together with the developer G (circulation indicated by broken line arrows in FIG. 3). .)

  In detail, referring to FIG. 3, the developer G in the first developer transport portion 53Y is moved from the right side to the left side by a first transport screw 55Y (screw-like rotating member) as a first developer transport unit. It is conveyed to. Thus, a first transport path for transporting the developer G along the longitudinal direction of the developing roller 51Y is formed. On the other hand, the developer G in the second developer transport portion 54Y is fed to the paper surface by a second transport screw 56Y and a third transport screw 57Y (two screw-shaped rotating members) as second developer transport means. It is conveyed from the left side to the right side. Thus, a second transport path for transporting the developer G in the direction opposite to the first transport path is formed.

Further, the first developer transport portion 53Y in which the first transport path is formed and the second developer transport portion 54Y in which the second transport path is formed are partitions arranged in regions excluding both longitudinal ends. It is isolated by the member and communicates at both longitudinal ends where no partition member is interposed. That is, the developer G transported by the first developer transport section 53Y flows to the upstream side of the second developer transport section 54Y in the first communication section A, and then the second developer transport section 54Y. It is transported by the second transport screw 56Y and the third transport screw 57Y (second developer transport means). The developer G transported by the second developer transport section 54Y flows to the upstream side of the first developer transport section 53Y in the second communication section B, and then the first developer transport section 53Y first. It is transported by a transport screw 55Y (first developer transport means). In other words, in the second developer conveying portion 54Y disposed so as to face the first developer conveying portion 53Y via the partition member, the first developer conveying portion 53Y is fed from the downstream side in the conveying direction. The developed developer G is transported in the longitudinal direction by the second transport screw 56Y and the third transport screw 57Y (second developer transport means) and is sent upstream in the transport direction of the first developer transport portion 53Y. Thus, a circulation path for the developer G is formed between the two developer transport portions 53Y and 54Y.
In the first embodiment, the second transport screw 56Y and the third transport screw 57Y installed in the second developer transport section 54Y are arranged such that the top position of the screw portion of the third transport screw 57Y is the second transport screw. Although it arrange | positions so that it may shift | deviate to a rotating shaft direction (it is the left-right direction of FIG. 3) with respect to the position of the top part of the 56Y screw part, this is demonstrated in detail later.

Thus, the toner in the developer G circulating in the circulation path is attracted to the carrier by frictional charging with the carrier and is carried together with the carrier on the developing roller 51Y in which a plurality of magnetic poles are formed.
Here, referring to FIG. 3, the developing roller 51Y includes a magnet 51b that is fixed inside and forms a plurality of magnetic poles on the circumferential surface of the roller, and a sleeve 51a that rotates around the magnet 23a1. . Then, when the sleeve 51a rotates around the magnet 51b on which a plurality of magnetic poles are formed, the developer G moves on the developing roller 51Y (on the sleeve 51a) with the rotation.

  The developer G carried on the developing roller 51Y as the developer carrying member is conveyed with the rotation of the developing roller 51Y in the direction of the arrow, and reaches the position of the doctor blade 52Y as the developer regulating member. Then, after the developer G on the developing roller 51Y is regulated to an appropriate amount at this position, the developer G is conveyed to a position facing the photosensitive drum 1Y (developing area). The toner is attracted to the latent image formed on the photosensitive drum 1Y by the electric field (developing electric field) formed in the developing area.

Specifically, a plurality of magnetic poles, such as a pumping magnetic pole, a main magnetic pole, a conveyance magnetic pole, and an agent separating magnetic pole, are formed around the developing roller 51Y (sleeve 51a) by the magnet 51b.
First, the pumping magnetic pole acts on a carrier as a magnetic material, and the developer G accommodated in the first developer transport portion 53Y is carried on the developing roller 51Y. A part of the developer G carried on the developing roller 51Y is scraped off at the position of the doctor blade 52Y (developer regulating member) and returned to the developer conveying portion 53Y. On the other hand, the developer G carried on the developing roller 51Y after passing through the doctor gap between the doctor blade 52Y and the developing roller 51Y rises at the position of the main magnetic pole and becomes a magnetic brush in the developing region. Touching 1Y. Thus, the toner in the developer G carried on the developing roller 51Y adheres to the latent image on the photosensitive drum 1Y. Thereafter, the developer G (toner concentration is low) that has passed through the position of the main magnetic pole (development region) is transported to the position of the agent separation magnetic pole by the transport magnetic pole. Then, the developer G after the developing process carried on the developing roller 51Y is detached from the developing roller 51Y at the position of the agent separating magnetic pole. The detached developer G is returned again to the first developer transport section 53Y and circulates in the two developer transport sections 53Y and 54Y. Such a flow of the developer G is repeated.
Here, the developer in the developing device 5Y is adjusted so that the toner ratio (toner concentration) in the developer is within a predetermined range. Specifically, according to the toner consumption in the developing device 5Y, the toner accommodated in the toner bottle 32Y as the powder accommodating portion is transferred into the second developer conveying portion 54Y through the toner replenishing port 64Y by the toner replenishing device. Will be replenished.

Referring to FIG. 2, after the development process described above, the surface of photoreceptor drum 1Y reaches a position facing intermediate transfer belt 8 and first transfer bias roller 9Y, and on this surface of photoreceptor drum 1Y. The toner image is transferred onto the intermediate transfer belt 8 (primary transfer process). At this time, a small amount of untransferred toner remains on the photosensitive drum 1Y.
Thereafter, the surface of the photosensitive drum 1Y reaches a position facing the cleaning unit 2Y, and untransferred toner remaining on the photosensitive drum 1Y at this position is mechanically collected by the cleaning blade 2a (in the cleaning process). is there.).
Finally, the surface of the photosensitive drum 1Y reaches a position facing a neutralization unit (not shown), and the residual potential on the photosensitive drum 1Y is removed at this position.
Thus, a series of image forming processes performed on the photosensitive drum 1Y is completed.

The image forming process described above is performed in the other image forming units 6M, 6C, and 6K in the same manner as the yellow image forming unit 6Y. That is, the laser beam L based on the image information is emitted from the exposure unit 7 disposed below the image forming unit onto the photosensitive drums of the image forming units 6M, 6C, and 6K. Specifically, the exposure unit 7 emits laser light L from a light source, and irradiates the photosensitive drum through a plurality of optical elements while scanning the laser light L with a polygon mirror that is rotationally driven.
Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 8 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 8.

  Here, referring to FIG. 1, the intermediate transfer unit 15 includes an intermediate transfer belt 8, four primary transfer bias rollers 9Y, 9M, 9C, 9K, a secondary transfer backup roller 12, and a plurality of tension rollers 12-14. The intermediate transfer cleaning unit 10 and the like. The intermediate transfer belt 8 is stretched and supported by a plurality of roller members 12 to 14 and is endlessly moved in the direction of the arrow in FIG.

The four primary transfer bias rollers 9Y, 9M, 9C, and 9K respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1K to form a primary transfer nip. Then, a transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 9Y, 9M, 9C, and 9K.
The intermediate transfer belt 8 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9K. In this way, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred while being superimposed on the intermediate transfer belt 8.

  Thereafter, the intermediate transfer belt 8 on which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19. At this position, the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 with the secondary transfer roller 19 to form a secondary transfer nip. The four-color toner images formed on the intermediate transfer belt 8 are transferred onto a recording medium P such as transfer paper conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 8.

Thereafter, the intermediate transfer belt 8 reaches the position of the intermediate transfer cleaning unit 10. At this position, the untransferred toner on the intermediate transfer belt 8 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 8 is completed.

Here, the recording medium P transported to the position of the secondary transfer nip is transported from a paper feeding unit 26 disposed below the apparatus main body 100 via a paper feeding roller 27, a registration roller pair 28, and the like. It is a thing.
Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 26 in a stacked manner. When the paper feed roller 27 is driven to rotate counterclockwise in FIG. 1, the uppermost recording medium P is fed toward the rollers of the registration roller pair 28.

  The recording medium P transported to the registration roller pair 28 temporarily stops at the position of the roller nip of the registration roller pair 28 whose rotation drive has been stopped. Then, the registration roller pair 28 is rotationally driven in synchronization with the color image on the intermediate transfer belt 8, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing unit 20. At this position, the color image transferred to the surface is fixed on the recording medium P by heat and pressure generated by the fixing roller and the pressure roller.
Thereafter, the recording medium P is discharged to the outside of the apparatus through the rollers of the discharge roller pair 29. The recording media P discharged to the outside of the apparatus by the discharge roller pair 29 are sequentially stacked on the stack unit 30 as an output image.
Thus, a series of image forming processes in the image forming apparatus is completed.

Hereinafter, the configuration and operation of the developing device 5Y, which are characteristic in the first embodiment, will be described in detail.
In the developing device 5Y according to the first embodiment, at least one of the first developer conveying unit and the second developer conveying unit is a plurality of screw-shaped rotating members. Specifically, as shown in FIGS. 2 to 6, as the second developer conveying means for conveying the developer in the longitudinal direction in the second developer conveying portion 54 </ b> Y, the second conveyance as two screw-shaped rotating members. A screw 56Y and a third transport screw 57Y are used.
And at least one conveyance screw among the plurality of conveyance screws 56Y and 57Y (screw-shaped rotating member) is such that the position of the top portion of the screw portion is in the rotational axis direction with respect to the position of the top portion of the screw portion of another conveyance screw. It arrange | positions so that it may slip | deviate. Specifically, referring to FIG. 3 and FIG. 4, the position of the top of the screw part 57Y1 (blade) of the third transport screw 57Y is set to the position of the top of the screw part 56Y1 (blade) of the second transport screw 56Y. On the other hand, it is configured to be shifted (offset) by a distance X in the rotation axis direction (the left-right direction in FIGS. 3 and 4). The distance X (deviation amount) is set to be greater than zero and smaller than the screw pitch of the screw portion 56Y1 of the second transport screw 56Y.

  By configuring in this way, in the second developer conveying portion 54Y, the developer G pumped upward by the screw portion (blade) of one conveying screw (the third conveying screw 57Y or the second conveying screw 56Y) The screw part (blade) of the other transport screw (second transport screw 56Y or third transport screw 57Y) approaches and acts to shear the developer G in the vertical direction. As a result, the developer G transported in the second developer transport section 54Y can move up and down without causing the toner replenished from the toner replenishing port 64Y to float on the upper surface of the developer G (without “sliding up”). It will be stirred and mixed efficiently and reliably in the direction. Therefore, the chargeability of the toner is also improved.

Here, with reference to FIG. 5 and the like, the developing device 5Y in the first embodiment is configured so that the two transport screws (the second transport screw 56Y and the third transport screw 57Y) rotate in the same direction. It is configured. Specifically, referring to FIG. 6, the gear train for rotationally driving the two transport screws 56Y and 57Y includes a gear 71Y installed on the shaft portion 56Y2 of the second transport screw 56Y and a shaft portion 57Y2 of the third transport screw 57Y. And an idler gear 73Y meshing with the two gears 71Y and 72Y (which is rotatably held by a stud (not shown) standing on the case of the developing device 5Y). The gear trains 71Y to 73Y are a region M surrounded by a broken line on the left side of FIG. 3 together with a gear train for rotationally driving the developing roller 51Y and the first transport screw 55Y. ) And receives a driving force from a developing motor (not shown). In addition, the straight arrow in FIG. 6 shows the conveyance direction of a developer.
As described above, the second transport screw 56Y and the third transport screw 57Y are disposed so that the top portions of the screw portions 56Y1 and 57Y1 do not overlap with each other in the rotation axis direction, and are driven to rotate in the same direction. The developer G pumped upward along the rotation of the third conveyance screw 57Y and the development moved downward along the rotation of the second conveyance screw 56Y at a position where the two conveyance screws 56Y and 57Y are close to each other. The agent G mixes up and down while colliding with each other. Thereby, the stirring property and charging property of the developer G in the developing device 5Y (second developer conveying portion 54Y) are enhanced.

Moreover, in this Embodiment 1, when it sees in the cross section orthogonal to a rotating shaft direction (refer FIG. 5), the screw part 57Y1 of 3rd conveyance screw 57Y (one screw-shaped rotation member), and 2nd The screw portion 56Y1 of the transport screw 56Y (an adjacent other screw-shaped rotating member) is configured to alternately approach the counterpart transport screw (screw-shaped rotating member) at different timings. Specifically, the second transport screw 56Y and the third transport screw 57Y are configured to rotate at the same phase and the same rotational speed. More specifically, the second transport screw 56Y and the third transport screw 57Y are formed such that the screw pitches and screw diameters of the screw portions 56Y1 and 57Y2 are the same, and are driven to rotate at the same rotational speed. . The second conveyance screw 56Y and the third conveyance screw 57Y are configured in the same manner except that the positions of the top portions of the screw portions 56Y1 and 57Y2 are alternately shifted in the rotation axis direction.
Thereby, the developer G is agitated and mixed in the vertical direction because the screw portions 56Y1 and 57Y2 of the second transport screw 56Y and the third transport screw 57Y periodically approach each other every rotation cycle. Opportunities are sufficiently secured and the balance of the developer is stabilized. Therefore, the stirring property and charging property of the developer G in the developing device 5Y (second developer conveying portion 54Y) are improved.

In the first embodiment, referring to FIG. 3, a toner replenishing port 64Y for replenishing toner is provided on the upstream side (the left side in FIG. 3) in the transport direction of the second developer transport portion 54Y. ing.
Thereby, it is possible to sufficiently secure the time for the toner to be stirred and mixed in the developer G by the two transport screws 56Y and 57Y in the second developer transport section 54Y. That is, the toner is agitated and mixed in the developer G by taking a sufficient time to move the path length of the second developer conveying portion 54Y.

In the first embodiment, the gear trains 71Y to 73Y that rotationally drive the two transport screws 56Y and 57Y (second developer transport means) are positioned at the top of the screw portion 57Y1 of the third transport screw 57Y. The two conveying screws 56Y are configured such that they cannot be assembled when they are not arranged so as to be displaced in the direction of the rotation axis with respect to the position of the top of the screw part 56Y1.
Specifically, referring to FIGS. 6 and 7, D-cut portions 56Y20 and 57Y20 as fitting portions are respectively provided on the drive-side shaft portions 56Y2 and 57Y2 of the second transport screw 56Y and the third transport screw 57Y. Is formed. And these D cut parts 56Y20 and 57Y20 are formed so that the phase of both screw parts 56Y1 and 57Y1 may shift | deviate, when D cut part 56Y20 and 57Y20 are turned right up.
On the other hand, the gears 71Y and 72Y installed on the two conveying screws 56Y and 57Y have D-shaped holes 71Y1 and 72Y1 as toothed portions to be fitted to the D-cut portions 56Y20 and 57Y20, and tooth surfaces. No flanges 71Y2 and 72Y2 are formed. Further, notches 71Y20 and 72Y20 are formed in part of the flange portions 71Y2 and 72Y2. The outer peripheral surfaces (the positions excluding the notches 71Y20 and 72Y20) of the flange portions 71Y2 and 72Y2 are formed at substantially the same height as the tooth tips of the gears 71Y and 72Y, and the notches 71Y20 and 72Y20 are gears 71Y and 72Y. It is formed at a position lower than the tooth bottom. When the notches 71Y20 and 72Y20 are not arranged so that the position of the top of the screw part 57Y1 of the third transport screw 57Y is shifted in the rotational axis direction with respect to the position of the top of the screw part 56Y1 of the second transport screw 56Y. In addition, the notches 71Y20 and 72Y20 with respect to the D-shaped holes 71Y1 and 72Y1 (fitting parts) so that the flanges 71Y2 and 72Y2 interfere with other gears (the idler gear 73Y in the first embodiment). The position of is determined.

Specifically, as shown in FIG. 7A, only when the D-cut portions 56Y20 and 57Y20 (D-shaped hole portions 71Y1 and 72Y1) of the two transport screws 56Y and 57Y are oriented directly above, As shown in FIGS. 7B1 to 7B2, the gear trains 71Y to 73Y are assembled without interfering with each other.
On the other hand, as shown in FIG. 7C, when the D-cut portions 56Y20 and 57Y20 (D-shaped hole portions 71Y1 and 72Y1) of the two transport screws 56Y and 57Y are not directed directly upward, 7 (D1) to (D2), the gear trains 71Y to 73Y are interfered with each other by broken-line circles and cannot be assembled.
With such a configuration, since the two conveying screws 56Y and 57Y are reliably assembled so that the phases of both the screw portions 56Y1 and 57Y1 are shifted, the above-described effect of improving the stirring property and charging property of the developer G can be obtained. It will surely be demonstrated.

  As described above, in the first embodiment, the first developer transport unit installed in the first developer transport unit 53Y, and the second developer transport unit installed in the second developer transport unit 54Y. , At least one of the plurality of transfer screws 56Y, 57Y (screw-like rotating member), the position of the top of the screw part 57Y1 of at least one transfer screw 57Y is the position of the top of the screw part 56Y1 of the other transfer screw 56Y. Is configured so as to be displaced in the direction of the rotation axis. Thus, the toner is sufficiently agitated and mixed in the developer in the circulation paths 53Y and 54Y of the developer G, and the problem that density unevenness occurs on the output image is reduced.

  In the first embodiment, some or all of the image forming units 6Y, 6M, 6C, and 6K may be a process cartridge. Even in that case, the same effects as those of the first embodiment described above can be obtained.

  In the first embodiment, the shafts 56Y2 and 57Y2 of the transport screws 56Y and 57Y are fitted to the fitting portions 56Y and 57Y in order to integrally rotate (drive transmission) the transport screws 56Y and 57Y and the gears 71Y and 72Y. D-cut portions 56Y20 and 57Y20 are provided, and gears 71Y and 72Y are provided with D-shaped hole portions 71Y1 and 72Y1 as fitted portions to be fitted to the D-cut portions 56Y20 and 57Y20. However, the configuration of the fitting portions formed on the shaft portions 56Y2 and 57Y2 of the conveying screws 56Y and 57Y and the fitted portions formed on the gears 71Y and 72Y is not limited to this. For example, the fitting portions formed on the shaft portions 56Y2 and 57Y2 of the conveying screws 56Y and 57Y are trapezoidal or egg-shaped, and the fitting portions formed on the gears 71Y and 72Y according to the shape are trapezoidal or It can also be an egg-shaped hole. The fitting portions formed on the shaft portions 56Y2 and 57Y2 of the conveying screws 56Y and 57Y are used as keys (or key grooves), and the fitted portions formed on the gears 71Y and 72Y are used as key grooves (or keys). You can also Even in those cases, the same effects as those of the first embodiment described above can be obtained.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 8 is an enlarged top view showing the second transport screw 56Y and the third transport screw 57Y of the developing device 5Y in the second embodiment, and corresponds to FIG. 4 in the first embodiment. FIG. 9 is a view of the second transport screw 56Y and the third transport screw 57Y of FIG. 8 as viewed in the direction of the rotation axis, and corresponds to FIG. 5 in the first embodiment. FIG. 10 is a perspective view showing a state where the gear trains 71Y and 72Y are installed on the second transport screw 56Y and the third transport screw 57Y of FIG. 8, and is a view corresponding to FIG. 6 in the first embodiment. is there. Further, FIG. 11 is a schematic diagram showing a state in which the gear trains 71Y and 72Y are assembled to the second transport screw 56Y and the third transport screw 57Y of FIG.
The developing device 5Y according to the second embodiment is different from the first embodiment in that the third transport screw 57Y rotates in a direction different from the rotation direction of the second transport screw 56Y.

Similarly to the first embodiment, the developing device 5Y according to the second embodiment is also provided with a first developer conveying portion 53Y and a second developer conveying portion 54Y that form a circulation path in the longitudinal direction of the developer. It has been. In the first developer conveying portion 53Y, a developing roller 51Y, a doctor blade 52Y, a first conveying screw 55Y (first developer conveying means), and the like are installed. The second developer conveying portion 54Y is provided with a second conveying screw 56Y, a third conveying screw 57Y (second developer conveying means), a toner supply port 64Y, and the like.
Referring to FIG. 8, also in the second embodiment, as in the first embodiment, the position of the top of the screw portion 57Y1 (blade) of the third transport screw 57Y is the same as that of the second transport screw 56Y. The screw portion 56Y1 (blade) is configured to be shifted (offset) by a distance X in the rotation axis direction (the left-right direction in FIG. 8) with respect to the position of the top portion of the screw portion 56Y1 (blade).

Here, referring to FIGS. 8 to 10, the developing device 5 </ b> Y in the second embodiment differs from that in the first embodiment in that a third transport screw 57 </ b> Y (one screw-like rotating member) is The second conveying screw 56Y (another screw-shaped rotating member) is configured to rotate in a direction different from the rotational direction. Specifically, the second transport screw 56Y rotates in the clockwise direction in FIG. 9, while the third transport screw 57Y rotates in the counterclockwise direction in FIG.
Referring to FIG. 10, the gear train for rotationally driving the two transport screws 56Y and 57Y is installed on the gear 71Y installed on the shaft portion 56Y2 of the second transport screw 56Y and on the shaft portion 57Y2 of the third transport screw 57Y. The two gears 71Y and 72Y mesh with each other. The gear trains 71Y and 72Y are regions M surrounded by a broken line on the left side of the developing device 5Y together with a gear train for rotationally driving the developing roller 51Y and the first transport screw 55Y. ) And receives a driving force from a developing motor (not shown). In addition, the straight arrow in FIG. 10 shows the conveyance direction of a developer.
Thus, the second transport screw 56Y and the third transport screw 57Y are disposed so that the top portions of the screw portions 56Y1 and 57Y1 do not overlap with each other in the rotation axis direction, and are driven to rotate in the opposite directions. The developer G pumped upward along the rotation of the third transport screw 57Y and the developer pumped upward along the rotation of the second transport screw 56Y at a position where the two transport screws 56Y and 57Y are close to each other. G and G are mixed up and down while colliding with each other so as to be confused with each other by shifting the timing in the direction of the rotation axis. Thereby, the stirring property and charging property of the developer G in the developing device 5Y (second developer conveying portion 54Y) are enhanced.

In particular, by shifting the phases of the screw portions 56Y1 and 57Y1 of the two conveying screws 56Y and 57Y and rotating the two conveying screws 56Y and 57Y in the opposite directions, the directions shown in FIGS. 12A1 and 12A2 are obtained. As shown, large irregularities are periodically formed on the upper surface (draft line) of the developer G in the second developer transport portion 54Y corresponding to the screw pitch. As a result, the developer G moves from a high position (convex portion) to a low position (concave portion) like an avalanche, and the agitation of the developer G is further enhanced.
12 (B1) and 12 (B2) show the two conveying screws 56Y and 57Y in the reverse direction without shifting the phases of the screw portions 56Y1 and 57Y1 of the two conveying screws 56Y and 57Y (distance X = 0). 6 shows the state of the upper surface (draft) of the developer G in the second developer transport section 54Y when it is rotationally driven. From this, it can be seen that large irregularities are formed on the upper surface (draft) of the developer G by shifting the phases of the screw portions 56Y1 and 57Y1 of the two transport screws 56Y and 57Y.
FIGS. 12A1 and 12B1 are front views showing only the developer G in the second developer transport portion 54Y in the height direction, and FIGS. 12A2 and 12B2 are FIGS. It is a perspective view showing developer G in the 2nd developer conveyance part 54Y with two conveyance screws 56Y and 57Y.

Also in the second embodiment, as in the first embodiment, when viewed in a cross section orthogonal to the rotation axis direction, the screw portion 57Y1 of the third transport screw 57Y (one screw-shaped rotating member), The screw portion 56Y1 of the second transport screw 56Y (an adjacent other screw-shaped rotating member) is configured to alternately approach the counterpart transport screw (screw-shaped rotating member) at different timings. Specifically, the second transport screw 56Y and the third transport screw 57Y are configured to rotate in the same phase and at the same rotation speed in the opposite direction. More specifically, the second transport screw 56Y and the third transport screw 57Y are formed such that the screw pitches and screw diameters of the screw portions 56Y1 and 57Y2 are the same, and are driven to rotate at the same rotational speed. . The second transport screw 56Y and the third transport screw 57Y are configured such that the positions of the tops of the screw portions 56Y1 and 57Y2 are alternately displaced in the rotation axis direction, and the spiral direction (twisting of the screw portions 56Y1 and 57Y2). The direction is the same except that the direction is set in the opposite direction.
Thereby, the developer G is agitated and mixed in the vertical direction because the screw portions 56Y1 and 57Y2 of the second transport screw 56Y and the third transport screw 57Y periodically approach each other every rotation cycle. Opportunities are sufficiently secured and the balance of the developer is stabilized. Therefore, the stirring property and charging property of the developer G in the developing device 5Y (second developer conveying portion 54Y) are improved.

Also in the second embodiment, as in the first embodiment, the gear trains 71Y and 72Y that rotationally drive the two transport screws 56Y and 57Y (second developer transport means) are provided on the third transport screw 57Y. When the position of the top part of the screw part 57Y1 is not arranged so as to be displaced in the direction of the rotation axis with respect to the position of the top part of the screw part 56Y1 of the second conveying screw 56Y, they are configured so that they cannot be assembled.
Specifically, referring to FIGS. 10 and 11, D-cut portions 56Y20 and 57Y20 (fitting portions) are respectively provided on the drive-side shaft portions 56Y2 and 57Y2 of the second transport screw 56Y and the third transport screw 57Y. Is formed. And these D cut parts 56Y20 and 57Y20 are formed so that the phase of both screw parts 56Y1 and 57Y1 may shift | deviate, when D cut part 56Y20 and 57Y20 are turned right up.
On the other hand, the gears 71Y and 72Y installed on the two conveying screws 56Y and 57Y do not have D-shaped hole portions 71Y1 and 72Y1 (fitting portions) that fit into the D-cut portions 56Y20 and 57Y20 and tooth surfaces. The flange portions 71Y2 and 72Y2 are formed. Further, notches 71Y20 and 72Y20 are formed in part of the flange portions 71Y2 and 72Y2. The outer peripheral surfaces (the positions excluding the notches 71Y20 and 72Y20) of the flange portions 71Y2 and 72Y2 are formed at substantially the same height as the tooth tips of the gears 71Y and 72Y, and the notches 71Y20 and 72Y20 are gears 71Y and 72Y. It is formed at a position lower than the tooth bottom. When the notches 71Y20 and 72Y20 are not arranged so that the position of the top of the screw part 57Y1 of the third transport screw 57Y is shifted in the rotational axis direction with respect to the position of the top of the screw part 56Y1 of the second transport screw 56Y. In addition, the positions of the notches 71Y20 and 72Y20 with respect to the D-shaped holes 71Y1 and 72Y1 are determined so that the flanges 71Y2 and 72Y2 interfere with each other. The flange 71Y2 of the gear 71Y installed on the second transport screw 56Y is disposed outside the insertion direction to the shaft 56Y20, and the flange 72Y2 of the gear 72Y installed on the third transport screw 57Y is It arrange | positions inside with respect to the insertion direction to axial part 57Y20.

Specifically, as shown in FIG. 11A, when the D-cut portions 56Y20 and 57Y20 (D-shaped hole portions 71Y1 and 72Y1) of the two transport screws 56Y and 57Y are both directed upward. Only, as shown in FIGS. 11B1 to 11B3, the gear trains 71Y and 72Y are assembled without interfering with each other.
On the other hand, as shown in FIGS. 11C and 11E, both of the D-cut portions 56Y20 and 57Y20 (D-shaped hole portions 71Y1 and 72Y1) of the two conveying screws 56Y and 57Y are directly above. 11 (D1) to (D2) and FIGS. 11 (F1) to (F2), the gear trains 71Y and 72Y must not be assembled by interfering with each other at the broken line circles. become.
With such a configuration, since the two conveying screws 56Y and 57Y are reliably assembled so that the phases of the two screw portions 56Y1 and 57Y1 are out of phase, the above-described effect of improving the stirring property and charging property of the developer G can be obtained. It will surely be demonstrated.

  In the second embodiment, as shown in FIG. 9, the two conveying screws 56Y and 57Y are moved so that the screw portions 56Y1 and 57Y1 of the two conveying screws 56Y and 57Y approach each other when moving upward from below. Were rotated in opposite directions. On the other hand, the two conveying screws 56Y and 57Y can be driven to rotate in opposite directions so that the screw portions 56Y1 and 57Y1 of the two conveying screws 56Y and 57Y approach each other when moving downward from above. . Specifically, the second transport screw 56Y can be rotated counterclockwise in FIG. 9 and the third transport screw 57Y can be rotated clockwise in FIG. Even in this case, the same effect as in the second embodiment can be obtained by rotating the two conveying screws 56Y and 57Y so that the phases of both screw portions 56Y1 and 57Y1 are shifted.

  As described above, also in the second embodiment, similarly to the first embodiment, the first developer conveying means installed in the first developer conveying unit 53Y and the second developer conveying unit 54Y are installed. At least one of the second developer conveying means thus formed is a plurality of conveying screws 56Y and 57Y (screw-like rotating member), and the top position of the screw portion 57Y1 of at least one conveying screw 57Y is the other conveying screw. The screw portion 56Y1 of 56Y is configured to be displaced in the rotation axis direction with respect to the position of the top portion. Thus, the toner is sufficiently agitated and mixed in the developer in the circulation paths 53Y and 54Y of the developer G, and the problem that density unevenness occurs on the output image is reduced.

  In each of the above embodiments, the two developer screws 56Y and 57Y are installed in the second developer transport unit 54Y. However, three or more transport screws (screw-shaped rotating members) are installed in the second developer transport unit 54Y. It can also be installed. Even in that case, the position of the top part of the screw part of at least one transport screw among the three or more transport screws installed is configured to deviate in the rotation axis direction with respect to the position of the top part of the screw part of the other transport screw. Thus, it is possible to obtain substantially the same effects as those of the above embodiments.

  In each of the above embodiments, the plurality of transport screws 56Y and 57Y are installed in the second developer transport unit 54Y, but the plurality of transport screws (screw-shaped rotating members) are installed in the first developer transport unit 53Y. Alternatively, a plurality of conveying screws (screw-shaped rotating members) can be installed in each of the first developer conveying portion 53Y and the second developer conveying portion 54Y. Even in that case, the position of the top of the screw part of at least one of the transport screws installed in one developing and transporting part is shifted in the rotational axis direction with respect to the position of the top of the screw part of the other transport screw. By configuring as described above, it is possible to obtain substantially the same effects as those of the respective embodiments.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view illustrating an image forming unit in the image forming apparatus of FIG. 1. FIG. 4 is a cross-sectional view of the developing device and the photosensitive drum as viewed from above. It is an enlarged top view which shows a 2nd conveyance screw and a 3rd conveyance screw. It is the figure which looked at the rotation axis direction of the 2nd conveyance screw and the 3rd conveyance screw. It is a perspective view which shows the state in which a gear train is installed in a 2nd conveyance screw and a 3rd conveyance screw. It is the schematic which shows the state by which a gear train is assembled | attached to a 2nd conveyance screw and a 3rd conveyance screw. It is an enlarged top view which shows the 2nd conveyance screw of the developing device in Embodiment 2 of this invention, and a 3rd conveyance screw. It is the figure which looked at the 2nd conveyance screw of FIG. 8, and the 3rd conveyance screw in the rotating shaft direction. It is a perspective view which shows the state in which a gear train is installed in the 2nd conveyance screw of FIG. 8, and a 3rd conveyance screw. It is the schematic which shows the state by which a gear train is assembled | attached to the 2nd conveyance screw of FIG. 8, and a 3rd conveyance screw. It is the schematic which shows the state of the developer accommodated in the 2nd developer conveyance part.

Explanation of symbols

1Y photosensitive drum (image carrier),
5Y developing device,
51Y developing roller (developer carrier),
52Y Doctor blade (developer regulating member),
53Y first developer transport section,
54Y second developer transport section,
55Y first conveying screw (first developer conveying means, screw-like rotating member),
56Y second conveying screw (second developer conveying means, screw-like rotating member),
57Y third conveying screw (second developer conveying means, screw-like rotating member),
56Y1, 57Y1 screw part, 56Y2, 57Y2 shaft part,
56Y20, 57Y20 D cut part (fitting part),
71Y-73Y gear,
71Y1, 72Y1 D-shaped hole (fitted part),
71Y2, 72Y2 collar, 71Y20, 72Y20 notch,
100 Image forming apparatus main body (apparatus main body).

Claims (10)

A developing device that contains a developer having a carrier and toner and that develops a latent image formed on an image carrier,
A developer carrying body facing the image carrying body and carrying a developer;
A first developer conveying section for supplying the developer to the developer carrying member while conveying the developer in the longitudinal direction by a first developer conveying means;
The developer is disposed so as to face the first developer conveying portion via a partition member, and the developer fed from the downstream side in the conveying direction of the first developer conveying portion is fed by the second developer conveying means. A second developer transport unit transported in the longitudinal direction and sent upstream in the transport direction of the first developer transport unit;
With
At least one of the first developer conveying means and the second developer conveying means is a plurality of screw-shaped rotating members,
At least one screw-shaped rotating member among the plurality of screw-shaped rotating members is arranged such that the position of the top of the screw part is shifted in the rotation axis direction with respect to the position of the top of the screw part of the other screw-shaped rotating member. A developing device provided.   The developing device according to claim 1, wherein the plurality of screw-like rotating members rotate in the same direction.   The developing device according to claim 1, wherein the one screw-shaped rotating member rotates in a direction different from a rotation direction of the other screw-shaped rotating member. A gear train that rotationally drives the plurality of screw-like rotating members;
The gear train is assembled when the position of the top portion of the screw portion of the one screw-shaped rotating member is not disposed so as to be displaced in the rotational axis direction with respect to the position of the top portion of the screw portion of the other screw-shaped rotating member. The developing device according to claim 1, wherein the developing device is configured not to be able to perform the operation. The gear train is formed with a fitted portion that fits into a fitting portion formed in a shaft portion of a plurality of screw-shaped rotating members, and has a notch in a part of a flange portion that does not have a tooth surface. Comprising a plurality of formed gears,
The plurality of gears are not arranged such that the position of the top of the screw part of the one screw-shaped rotating member is displaced in the rotational axis direction with respect to the position of the top of the screw part of the other screw-shaped rotating member. The developing device according to claim 4, wherein a position of the notch with respect to the fitted portion is determined so that the flange portion interferes with another gear.   When viewed in a cross section orthogonal to the rotation axis direction, the screw portion of the one screw-shaped rotating member and the screw portion of the other screw-shaped rotating member adjacent to each other are at different timings. The developing device according to claim 1, wherein the developing device is configured to alternately approach each other.   The plurality of screw-like rotating members are formed so that screw pitches and screw diameters of the screw portions are the same, and are driven to rotate at the same rotational speed. The developing device according to any one of the above. The plurality of screw-like rotating members are disposed in the second developer transport unit,
The first developer conveying means is a single screw-shaped rotating member,
8. The developing device according to claim 1, wherein the second developer transport unit includes a toner supply port that supplies toner to the upstream side in the transport direction. 9. A process cartridge that is detachably attached to the image forming apparatus main body,
9. A process cartridge in which the developing device according to claim 1 and the image carrier are integrated.   An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

Images