JP5310363B2 - Developing device, process cartridge, image forming apparatus - Google Patents

Description

  The present invention relates to a developing device used in an electrophotographic image forming apparatus, and more particularly to a developing device using a developer including toner and a carrier.

  As a developing device incorporated in an electrophotographic image forming apparatus, a toner that converts a latent image formed on a photoconductor into a toner image, a carrier that charges the toner by stirring, and transports the toner to the photoconductor There is a type using a developer comprising This developing device can replenish only the toner as appropriate because the amount of toner in the developer decreases each time the latent image is developed into a toner image.

  The replenished toner needs to be sufficiently agitated with the stored developer. However, since the specific gravity of the carrier in the developer is larger than the specific gravity of the toner, it is difficult for the toner having a low specific gravity to enter the developer, so that the replenished toner slides on the powder surface of the developer. In some cases, it moves (hereinafter referred to as “upslip”) and is transferred to a developer carrying member such as a developing roller or a developing sleeve that supplies toner to the photosensitive member.

  Then, the toner is in a state where charging with a predetermined polarity due to friction with the carrier is insufficient or uncharged, and as a result, problems such as background contamination and toner scattering occur. In addition, due to insufficient stirring, toner density unevenness occurs, causing image density unevenness.

  In order to solve such problems, the following developing devices have been proposed.

  A developing device has been proposed in which means for independently driving the agitating member is provided and the number of revolutions of the agitating member is changed independently when toner is supplied (see, for example, Patent Document 1).

  A developing device that changes the stirring condition of the stirring means in accordance with the toner concentration level of the developer has been proposed (see, for example, Patent Document 2).

  There has been proposed a developing device provided with a scattering prevention member for preventing toner replenished from the toner replenishing portion from sliding on the surface of the developing powder and being conveyed to the screw portion on the developing roller side without being charged (for example, (See Patent Document 3).

  There has been proposed a developing device that operates the developer path regulating member in the developing device so as to be close to the developing roller to increase the charge amount (for example, see Patent Document 4).

  However, the techniques disclosed in Patent Document 1 and Patent Document 2 do not take into account a change in the state of the developer due to the repetition of the copying process, and thus there is a possibility that a sufficient effect cannot be obtained. Special cases such as when copying high-image area originals, especially after repeated long-term copying processes, or after long-term image formation that consumes less toner, such as continuous feeding of blank paper or low-image area originals In use, there was a risk that the effect would not last.

  The technique disclosed in Patent Document 3 focuses on the uniform dispersion of the toner among the two conditions that must be satisfied before the toner is transported to the developing unit. There was a risk that the charging of the battery becomes insufficient.

  In the technique disclosed in Patent Document 4, although the rubbing force applied to the developer increases, the place where the developer is regulated is in the vicinity of the doctor blade, so that the toner is not completely dispersed until the developer is conveyed to that position. In some cases, density unevenness may occur even when a doctor blade is used.

  The present invention has been made in view of such a situation, and can improve the dispersibility of the replenishing toner, prevent background stains and toner scattering, and output a good image without unevenness in image density. Another object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus capable of further space saving.

  In order to solve the above problems, the developing device, the process cartridge, and the image forming apparatus according to the present invention employ the following technical means.

  According to the first aspect of the present invention, a partition wall having a required length shorter than a side wall on the long side of the side wall portion is surrounded by the side wall portion at an inner middle portion of the side wall portion formed in a substantially rectangular shape in a transverse plan view. The machine frame portion that extends toward the short side wall of the side wall portion to form a pair of space portions sandwiching the partition wall in a longitudinal side view, and the pair of space portions are long in length. A pair of rotatable conveying screws erected across the direction, and a pair of the above-mentioned developer so that the developer having toner and carrier circulates in one direction across the partition wall in a cross-sectional plan view Of the pair of transport screws, the transport screw unit configured to be transportable by a transport screw, and the first transport screw that rotates and transports the developer so as to float toward the partition wall. The machine frame is supported in a rotatable manner across the direction. Of the stirrer provided on the support shaft with protrusions capable of entering between the blades of the first conveying screw, the support shaft, and a pair of long side walls of the side wall portion. A toner supply port provided between the long side wall in the vicinity of the support shaft and above the stirring member, and for supplying the toner to the inside of the machine frame, and the pair of transport screws. A developer carrying member provided above the remaining second carrying screw and carrying the developer carried by the carrying screw unit to supply the toner to a photoreceptor on which a latent image is formed; And a developing device.

  The invention according to a second aspect is characterized in that, in the first aspect, the projection is provided in a spiral shape on the support shaft at a required interval in the circumferential direction.

  According to a third aspect of the present invention, in the first or second aspect, the support shaft rotates in the same direction as the rotation direction of the pair of conveying screws.

  According to a fourth aspect of the present invention, there is provided a process cartridge including the developing device according to any one of the first to third aspects and the photosensitive member.

  According to a fifth aspect of the invention, an image forming apparatus including the process cartridge according to the fourth aspect is characterized.

  According to a sixth aspect of the present invention, there is provided an image forming apparatus including the developing device according to any one of the first to third aspects.

  According to the present invention, of the pair of transport screws, the protrusion of the stirring member is inserted between the blades of the first transport screw that is rotated and transported so that the developer floats toward the partition wall. Since the stirring efficiency of the agent is increased by shearing the agent, the dispersibility of the replenishing toner can be improved.

  Further, a toner replenishing port for supplying toner to the inside of the machine frame portion is provided between the support shaft and the long side wall near the support shaft among the pair of long side walls constituting the side wall portion. In addition, since the toner from the toner supply port falls to the lower side of the inclined powder surface, the upper slip can be suppressed by being provided above the stirring member.

  Furthermore, by providing the stirring member above the first conveying screw, the lateral space of the developing device is reduced, and space saving is achieved even in an apparatus in which a plurality of developing devices are arranged side by side, such as a color image forming apparatus. Can be planned.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. It is a vertical side view of a process cartridge. FIG. 3 is a cross-sectional plan view taken along line (X)-(X) in FIG. 2. It is a vertical side view along the (Y)-(Y) line of FIG.

  An embodiment of a developing device according to the present invention will be described.

  The developing device according to the present embodiment is illustrated as being incorporated in a process cartridge configured to be detachable from the main body of the image forming apparatus together with a photosensitive drum, a charging roller, and the like.

  First, an outline of an image forming apparatus loaded with the process cartridge will be described with reference to FIG.

  The image forming apparatus according to the present embodiment exemplifies a full-color laser printer that receives data transmitted from the outside and forms an image on a sheet based on the data.

  As shown in FIG. 1, the image forming apparatus includes an endless intermediate transfer belt 3 that is hung on a roller portion including a driving roller 1 and a driven roller 2 and can rotate counterclockwise, and the intermediate transfer belt. 3, a primary transfer roller 4 provided at a predetermined interval along the inner side of the lower running side, and process cartridges 5 </ b> Y, 5 </ b> C, 5 </ b> M disposed opposite to the primary transfer roller 4 across the lower running side of the intermediate transfer belt 3. 5K, the exposure device 6 disposed below the process cartridges 5Y, 5C, 5M, and 5K, the paper tray 7 disposed below the exposure device 6, and the paper provided near the paper tray 7 A feed roller 8, a secondary transfer roller 9 disposed opposite to the driving roller 1 with the intermediate transfer belt 3 interposed therebetween, and a resist provided between the secondary transfer roller 9 and the paper feed roller 8. A fixing device 11 disposed above the roller pair 10, the driving roller 1, and the secondary transfer roller 9, a paper discharge tray 12 formed on the upper surface of the image forming apparatus, and the fixing device 11 fix the toner image. A paper discharge roller pair 13 that discharges the discharged paper onto the paper discharge tray section 12.

  Of these, as shown in FIG. 1, the process cartridges, which are the main parts of the present invention, are four of yellow process cartridge 5Y, magenta process cartridge 5M, cyan process cartridge 5C, and black process cartridge 5K. Each of them is detachably installed in the main body of the image forming apparatus.

  Further, as shown in FIG. 2, the process cartridges 5Y, 5C, 5M, and 5K include a cartridge case 14 and a photosensitive drum as an image carrier that is provided in a substantially central upper portion of the cartridge case 14 so as to be rotated clockwise. 15 and the vicinity of the top of the outer peripheral surface of the photosensitive drum 15 are set as transfer positions at which the toner image on the photosensitive drum 15 is transferred to the intermediate transfer belt 3, and the photosensitive drum 15 is sequentially clockwise with respect to the transfer position. There are a brush roller 16 for removing unnecessary materials such as residual toner, carrier, paper dust and the like, a cleaning blade 17 for removing unnecessary materials, a charging roller 18 for uniformly charging the surface of the photosensitive drum 15, and a developing device 19. It is arranged.

  The process cartridge is configured so that a photosensitive drum 15, a later-described component such as a developing sleeve and a conveying screw unit that requires a rotational driving force, and a rotation shaft on the image forming apparatus main body side can be engaged. By setting the process cartridge in the image forming apparatus main body, the process cartridge is connected to the rotation shaft on the image forming apparatus main body side, and the rotation driving force of the rotation shaft on the image forming apparatus main body side is transmitted to rotate. .

  An opening that communicates with the outside is formed below the cartridge case 14 between the charging roller 18 and the developing device 19, and scanning light from the exposure device 6 is transmitted through the opening to the photosensitive drum 15. It comes to be irradiated. The developing device 19 described above develops the latent image into a toner image on the photosensitive drum 15 formed by the scanning light from the exposure device 6. The details of the developing device 19 which is a main part of the present invention will be described later.

  Further, the brush roller 16 is elastically biased with a lubricant 20 made of a metal soap such as zinc stearate. By applying the lubricant 20 to the photosensitive drum 15, the toner image peelability, that is, The transfer efficiency is increased.

  Below the brush roller 16, there is provided an undesired material conveying screw 21 that conveys unnecessary materials and the like removed by the brush roller 16 and the cleaning blade 17 to a storage unit (not shown).

  Below the charging roller 18, a cleaner roller 22 that rotates following the charging roller 18 to clean the outer peripheral surface of the charging roller 18 is provided.

A series of operations of the image forming apparatus configured as described above will be described.
The photosensitive drum 15 is rotated in the clockwise direction in the drawing by a driving unit (not shown), and the surface of the photosensitive drum 15 is uniformly charged to a predetermined polarity by the charging roller 18. Scanning light is irradiated from the exposure device 6 toward the charged surface of the photosensitive drum 15, whereby a latent image is formed on the surface of the photosensitive drum 15. At this time, the image information exposed on each photosensitive drum 15 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The electrostatic latent image is visualized as a toner image by the developing device 19.

  Further, the intermediate transfer belt 3 rotates counterclockwise in the drawing, and the respective color toner images are sequentially transferred from the photosensitive drum 15 to the intermediate transfer belt 3 by the action of the primary transfer roller 4 in each of the process cartridges 5Y, 5C, 5M, and 5K. Repeat transfer. In this way, a full-color toner image is formed on the surface of the intermediate transfer belt 3. Note that a single color image is formed using any one of the process cartridges 5Y, 5C, 5M, and 5K, or two or three of the plurality of process cartridges 5Y, 5C, 5M, and 5K are used. A color or three-color image can also be formed. In the case of monochrome printing, among the four process cartridges 5Y, 5C, 5M, and 5K, image formation is performed using the rightmost black process cartridge 5K in the drawing.

  Before and after the above operation, the sheet feeding roller 8 starts conveying the sheet from the sheet tray 7. The sheet that has started to be conveyed is sent out toward the secondary transfer position by the registration roller pair 10 in accordance with the movement of the toner image carried on the intermediate transfer belt 3, and the surface of the intermediate transfer belt 3 by the secondary transfer roller 9. The toner image is transferred. The sheet carrying the toner image is sent to the fixing device 11, and the toner image is melted and fixed on the sheet by heat and pressure, and is discharged to the discharge tray unit 12 by the discharge roller pair 13.

Next, the developing device 19 which is a main part of the present invention will be described in detail.
The developing device 19 according to the present embodiment includes a machine frame portion, a conveying screw portion, a stirring member 25, a developer carrier 26, a doctor blade 27, and a toner concentration sensor 28.

  The machine frame portion is provided with a conveyance screw portion, a stirring member 25, a developer carrier 26, a doctor blade 27, a toner concentration sensor 28, and the like, which will be described later, and is constituted by a part of the cartridge case 14 described above. The lower case part 14a and the upper case part 14b are provided.

  As shown in FIG. 2, the lower case portion 14 a has a concave curve in which two semicircles having a diameter slightly larger than the blade diameters of the first conveying screw 23 and the second conveying screw 24 described later are continuous in a longitudinal side view. Shaped bottom portion 14c, a partition wall 14d erected from the center of the bottom portion 14c, side walls are erected in the left-right direction, the depth direction, and the front direction across the partition wall 14d, and the side wall on the photosensitive drum 15 side is A side wall portion 14e obliquely provided on the side of the photosensitive drum 15 from the middle portion with respect to the other side wall. Further, as shown in FIG. 3, the partition wall 14d described above has a required length shorter than the long side wall 14g in a cross-sectional plan view, and is formed between both ends of the partition wall 14d and the short side wall 14f on both sides. Are extended toward the side wall 14f on the short side so that a gap is formed in the wall and surrounded by the side wall part 14e.

  The upper case portion 14b is configured to cover the upper portion of the lower case portion 14a so that a required opening is formed above the side wall on the photosensitive drum 15 side. The upper case portion 14b is provided with a toner replenishing port 14h, the details of which will be described later.

  In this way, the machine frame portion is provided with a partition wall 14d having a required length shorter than the side wall 14g on the long side of the side wall portion 14e at the inner middle portion of the side wall portion 14e formed in a substantially rectangular shape in a cross-sectional plan view. Are extended toward the side wall 14f on the short side of the side wall part 14e, and a pair of space parts are formed with the partition wall 14d interposed therebetween in a vertical side view. Of the pair of space portions, the left space portion in FIG. 2 is referred to as a first space portion a1, and the right space portion in FIG. 2 is referred to as a second space portion a2.

  The conveyance screw unit includes a first conveyance screw 23 and a second conveyance screw 24.

  The first conveying screw 23 is a shaft-like member in which a spiral blade 23b is formed over a required length on a support shaft 23a, and the blade 23b is a bottom portion over the longitudinal direction of the first space portion a1. 14c and is rotated in the counterclockwise direction in FIG. 2 so that the blade 23b moves from the back side to the near side in an apparent manner so that it can be rotated around the machine frame. Yes.

  Similar to the first transport screw 23, the second transport screw 24 is a shaft-like member in which a spiral blade 24b is formed over a required length on a support shaft 24a. The machine frame so that the blade 24b moves from the back side to the near side in appearance by rotating the blade 24b along the bottom portion 14c in the longitudinal direction and rotating counterclockwise in FIG. It is constructed so as to be rotatable on the part.

  The transport screw portion configured in this manner rotates both the first transport screw 23 and the second transport screw 24 installed in the longitudinal direction in each of the pair of space portions in the counterclockwise direction. As shown in FIG. 3, the developer D having toner and carrier circulates in one direction across the partition wall 14d in a plan view.

  Further, as described above, the rotation of the first conveying screw 23 and the second conveying screw 24 rotates counterclockwise in FIG. 2, but in other words, the first conveying screw 23 is not developed. The agent D rotates so as to float toward the partition wall 14d by the blade 23b, and the second transport screw 24 rotates so that the developer D floats toward the partition wall on the photosensitive drum 15 side by the blade 24b. Therefore, as shown in FIG. 2, the powder spaces of the first space part a1 and the second space part a2 and the respective developer D form an upwardly inclined shape.

  The agitating member 25 has a shaft-like protrusion 25b that is spirally provided on the support shaft 25a, and as shown in FIGS. 2 and 4, the center of the support shaft 23a of the first conveying screw 23 in the vertical direction. It can be rotated to the machine frame part in the longitudinal direction directly above the first conveying screw 23 so that the axis center is located on the line and the protrusion 25b enters between the blades 23b of the first conveying screw 23. It is built on.

  As shown in FIG. 4, the protrusion 25b has an axial length corresponding to one pitch of the blade 23b of the first conveying screw 23 with an interval of 1/4 pitch in the axial direction. The first conveyance screw is provided in a spiral shape at intervals of 90 degrees in the circumferential direction, and rotates at the same speed as the rotation speed of the first conveyance screw 23 and counterclockwise in FIG. The protrusion 25b always enters between the blades 23b without interfering with the 23 blades 23b, and the developer D is agitated.

  As described above, the toner replenishing port 14h is provided in the upper case portion 14b. As shown in FIG. 2, the arrangement positions thereof include the support shaft 25a of the stirring member 25 and the side wall portion 14e. Of the pair of long side walls 14g, the long side wall 14g in the vicinity of the support shaft 25a, that is, the upper side between the left side wall in FIG. Further, a toner replenishing device 30 is connected above the toner replenishing port 14h so that toner can be replenished as appropriate.

  The developer carrier 26 is fixed above the second conveying screw 24 in the machine frame, and a magnet roller (not shown) for causing the developer D to rise, and this magnet roller are loosely inserted in FIG. And a rotation sleeve (not shown) provided in the machine frame portion so as to be able to rotate counterclockwise, and in the opening formed above the side wall on the photosensitive drum 15 side, substantially the right half of the rotation sleeve. It is provided so that the outer peripheral surface of may be exposed. The developer carrier 26 configured as described above is configured to pump up the developer D being moved by the second conveying screw 24 by the action of magnetic force and convey it to the photosensitive drum 15 side. The separation distance (gap) of the closest portion between the surface of the rotating sleeve and the surface of the photosensitive drum is about 0.3 mm.

  The doctor blade 27 is a belt-like member having a base portion fixed to an end portion of a side wall obliquely provided on the photosensitive drum 15 side and a front portion thereof being close to or in contact with the developer carrier 26. The developer D on 26 is leveled to a predetermined thickness.

  The toner density sensor 28 detects the ratio of the toner contained in the developer D based on a change in magnetic permeability, and is provided below the second conveying screw 24 and on the machine frame bottom 14c near the photosensitive drum. Yes. In this way, by providing the toner concentration sensor 28 at a position close to the position where the developer D is pumped up by the developer carrier 26, it is possible to detect the concentration with reliability. When the toner ratio is lowered to a predetermined value by the toner density sensor 28, the toner is supplied from the toner supply device 30 through the toner supply port 14h.

  Next, the operation and effect at the time of development of the developing device 19 according to this embodiment configured as described above will be described.

  When the photosensitive drum 15 is rotated in the clockwise direction in FIG. 2 by a driving means (not shown), the first conveying screw 23, the second conveying screw 24, and the stirring member 25 are respectively moved by a driving means (not shown). In FIG. 2, it rotates counterclockwise.

  The developer D in the first space part a1 is into the second space part a2, the developer D in the second space part a2 is into the first space part a1, and the developer D is the partition wall 14d. Go around with a circle. At this time, the developer D is sheared so that the protrusion 25b of the stirring member 25 is inserted between the blades 23b of the first conveying screw 23.

Here, the stirring of the developer D will be described in detail.
When the height of the powder surface is shown in descending order, the relationship is as follows.
(High)> Right side of first conveying screw 23> Overlapping portion of first conveying screw 23 and stirring member 25> Left side of stirring member 25> (Low)
The portion of the stirring member 25 on the left side of the support shaft 25a has the lowest powder surface. By supplying toner there, the supplied toner is splashed from the right side of the stirring member 25. Since the underside of the stirring member 25 is submerged so as to be covered from above, the upper slip is suppressed.

  The developer D being transported by the first transport screw 23 is scraped off by the blades 23b of the first transport screw 23 and goes under the lower surface of the first transport screw 23.

  At this time, in the part where the first conveying screw 23 and the stirring member 25 overlap, the effect of stirring the developer D from the top to the bottom by the counterclockwise rotation of the first conveying screw 23, A counterclockwise rotation causes the effect that the developer D jumps up from the bottom at the same time, and a large shearing force is generated in the developer D. Since the magnitude of this elastic force varies depending on the position in the longitudinal direction of the conveyance path, a force in a complicated direction is applied to the developer D, and the stirring of the developer D is promoted.

  In this way, since the replenishment toner does not slip up, it dives into the developer D and is agitated, so that the toner remains uncharged and does not enter the second space a2.

  Further, since the protrusions 25b of the stirring member 25 are arranged in a spiral shape, the stirring member 25 also has a function as a transport member in addition to simply stirring because the transport force is generated.

  The powder surface of the developer D in the first space part a1 and the powder surface of the developer D in the second space part a2 respectively form a slope that rises to the right in FIG. In particular, the upper side of the powder surface of the developer D in the second space a <b> 2 reaches the top of the doctor blade 27.

  The developer carrier 26 draws up the developer D by the action of magnetic force, and conveys the developer D to the photosensitive drum 15 side by the doctor blade 27 in a state where the developer D is equalized to a predetermined thickness. The toner in developer D is electrostatically transferred to a latent image formed on the surface of the photosensitive drum, and the latent image is visualized as a toner image.

  The toner density sensor 28 detects the ratio of the toner in the developer D, and when the toner ratio falls to a predetermined value, the left side in FIG. 2 and the support shaft 25a of the stirring member 25 of the upper case portion 14b. The toner is replenished from the toner replenishing device 30 through a toner replenishing port 14h provided at a predetermined position above the side wall.

  As described above, according to the developing device 19 according to the present embodiment, the developer D is sheared by inserting the protrusion 25b of the stirring member 25 between the blades 23b of the first transport screw 23. Therefore, the stirring efficiency can be increased. In particular, since the rotation direction of the first conveying screw 23 and the stirring member 25 is the same direction (counterclockwise in FIG. 2), the developer D above the support shaft 23a of the first conveying screw 23 is reduced. 2, the protrusion 25 b that moves from the right to the left in FIG. 2 and is located below the support shaft 25 a of the stirring member 25 moves from the left to the right in FIG. 2 to shear the developer D. Therefore, the stirring efficiency can be further increased.

  Further, a toner replenishing port 14h for replenishing toner inside the machine frame portion is provided at a required position of the upper case portion 14b above the support shaft 25a of the stirring member 25 and the left side wall in FIG. As a result, the toner from the toner replenishing port 14h falls to the lower side of the inclined powder surface that rises to the right and suppresses the upward slipping, so that the dispersibility of the replenishing toner can be improved. In addition, since the toner dropped to the lower side of the inclination is stirred by the stirring member 25 so as to be submerged in the developer D, it is possible to further suppress the upward slip and improve the dispersibility of the replenishment toner.

  Furthermore, by providing the stirring member 25 above the first conveying screw 23 described above, the space in the lateral direction of the developing device 19 is reduced, and even in a device in which a plurality of developing devices 19 are arranged side by side, such as a color image forming device. Space can be saved.

  The developing device, the process cartridge, and the image forming apparatus according to the present embodiment have been described above. However, the above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto. However, various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Drive roller 2 ... Follower roller 3 ... Intermediate transfer belt 4 ... Primary transfer roller 5Y, 5C, 5M, 5K ... Process cartridge 6 ... Exposure device 7 ... Paper tray 8 ... Paper feeding roller 9 ... Secondary transfer roller 10 ... Resist Roller pair 11 Fixing device 12 Discharge tray part 13 Discharge roller pair 14 Cartridge case 14a Lower case part 14b Upper case part 14c Bottom part 14d Partition 14e Side wall part 14f Short side wall 14g Long side wall 14h ... Toner supply port 15 ... Photosensitive drum 16 ... Brush roller 17 ... Cleaning blade 18 ... Charging roller 19 ... Developing device 20 ... Lubricant 21 ... Unnecessary material transport screw 22 ... Cleaner roller 23 ... First Transfer screw 23a ··· Spindle 23b · · · Blade 24 · · · Second transfer Screw 24a... Support shaft 24b... Blade 25 .. Stirring member 25a... Support shaft 25b... Projection 26 .. Developer carrier 27 ... Doctor blade 28 ... Toner concentration sensor a1 ... First space part a2 ... Second space part 30. Toner supply device D ... Developer

JP-A-6-3950 Japanese Patent Laid-Open No. 10-198089 JP-A-9-106161 JP-A-11-202573

Claims (6)

The short side wall of the side wall portion is surrounded by the side wall portion so that a partition wall having a required length shorter than the side wall on the long side of the side wall portion is surrounded by the inner side middle portion of the side wall portion formed in a substantially rectangular shape in a transverse plan view. A machine frame part extending toward the side wall, and forming a pair of space parts across the partition wall in a longitudinal side view;
Each of the pair of space portions is provided with a pair of rotatable conveying screws erected in the longitudinal direction, and a developer having toner and a carrier is disposed in one direction across the partition in a cross-sectional plan view. A transport screw unit configured to be transportable by a pair of the transport screws,
Of the pair of transport screws, a spindle that is rotatable on the machine frame portion in the longitudinal direction directly above the first transport screw that rotates and transports the developer so as to float toward the partition wall. And a stirring member provided with a protrusion that can enter between the blades of the first conveying screw on the support shaft,
Provided between the support shaft and a long side wall in the vicinity of the support shaft of the pair of long side walls of the side wall portion, and above the stirring member; A toner supply port for supplying the toner therein;
Of the pair of transport screws, the toner is supplied to the photosensitive member that is provided above the remaining second transport screw and has the developer transported by the transport screw unit and on which a latent image is formed. A developer carrier;
A developing device comprising:   The developing device according to claim 1, wherein the protrusion protrudes spirally from the support shaft at a required interval in the circumferential direction.   The developing device according to claim 1, wherein the support shaft rotates in the same direction as a rotation direction of the pair of conveying screws.   A process cartridge comprising: the developing device according to claim 1; and the photosensitive member.   An image forming apparatus comprising the process cartridge according to claim 4.   An image forming apparatus comprising the developing device according to claim 1.

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