JP4887762B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus having the developing device.

  An electrophotographic image forming apparatus applied to a printer, a copying machine, or the like includes, for example, a developing device filled with a two-component developer composed of toner and a magnetic carrier. If the developer is not sufficiently stirred in the developing device, charging failure of the developer occurs and it is difficult to obtain a good image after development. Therefore, for example, the rotating shaft of the agitating and conveying member is formed narrowly or not over the required length range before and after the toner dropping portion below the toner replenishing port, and the blade area of the spiral blade in the length range is reduced to the blades on both sides thereof. Those that are formed wider than the area and improve the stirring property of the developer are known (for example, Patent Document 1).

JP-A-6-83184

  However, in the above-described conventional invention, since the range in which the blade area of the stirring and conveying member is formed is only below the toner supply port, the developer tends to be insufficiently stirred. Further, it is conceivable that by reducing (or eliminating) the rotating shaft of the agitating / conveying member, the strength of the agitating / conveying member is lowered and the agitating / conveying member is bent.

  An object of the present invention is to provide a developing device and an image forming apparatus that solve the above-described conventional problems and improve the stirring property of the developer.

  In order to achieve the above object, a first feature of the present invention is that in a developing device that transports and agitates a two-component developer comprising a toner and a carrier by a transport unit, the transport unit includes a rotating support shaft. And a stirring blade provided on the support shaft, and the support shaft has a large diameter portion and a small diameter portion smaller in diameter than the large diameter portion, and sandwiches the large diameter portion to The developing device is provided with a plurality of small diameter portions. Therefore, in the developer conveyed by the conveying means, a plurality of portions where the developer position is high (distance from the rotation center is long) and portions where the developer position is low (distance from the rotation center) are formed. The stirrability of the developer is improved. Accordingly, the charging failure of the developer is suppressed, and a good image after development can be obtained.

  Preferably, a toner supply port through which toner is supplied is provided opposite to the small diameter portion. Accordingly, accumulation of toner supplied from the toner supply port is prevented.

  Preferably, a stirring member extending in a diameter direction of the support shaft is provided in a large diameter portion upstream of the small diameter portion in the developer conveying direction. Therefore, in the developer transported in the developer transport direction, the height of the portion where the developer position is high (the distance from the rotation center is long) and the portion where the developer position is low (the distance from the rotation center is short) is high. The difference is further enlarged.

  Preferably, a stirring member extending in a diameter direction of the support shaft is provided in a large diameter portion downstream of the small diameter portion in the developer conveying direction. Therefore, in the developer transported in the developer transport direction, the height of the portion where the developer position is high (the distance from the rotation center is long) and the portion where the developer position is low (the distance from the rotation center is short) is high. The difference is further enlarged.

  A second feature of the present invention is that in a developing device that transports and agitates a two-component developer composed of toner and carrier by a transport unit, the transport unit is provided on a rotating support shaft and the support shaft. The support shaft has a large-diameter portion and a small-diameter portion having a smaller diameter than the large-diameter portion, and the agitating blade provided in the small-diameter portion is formed in multiple lines. In the developing device. Therefore, the developer in the small diameter portion is further agitated and reliably conveyed in the conveyance direction. In addition, the strength of the small-diameter portion is reinforced, and bending of the support shaft due to insufficient strength is prevented.

  A third feature of the present invention is that in a developing device that transports and agitates a two-component developer composed of toner and a carrier by a transport unit, the transport unit is provided on a rotating support shaft and the support shaft. The support shaft has a large diameter portion and a small diameter portion smaller in diameter than the large diameter portion, and the stirring blade provided in the small diameter portion includes the large diameter portion. The developing device has a pitch shorter than that of the stirring blade provided in the developing device. Therefore, the developer in the small diameter portion is further agitated and reliably conveyed in the conveyance direction. In addition, the strength of the small-diameter portion is reinforced, and bending of the support shaft due to insufficient strength is prevented.

  According to a fourth aspect of the present invention, in the developing device for transporting and stirring the two-component developer composed of toner and carrier by the transport unit, the transport unit is provided on the rotating support shaft and the support shaft. The support shaft has a large diameter portion and a small diameter portion smaller in diameter than the large diameter portion, and the stirring blade provided in the small diameter portion includes the large diameter portion. The developing device is thicker than the stirring blades provided in Therefore, the strength of the small diameter portion is reinforced, and the support shaft is prevented from bending due to insufficient strength.

  The fifth feature of the present invention is that it has an image carrier on which a latent image is formed, and a developing device that develops the latent image formed on the image carrier, and the developer device includes a toner And a carrier that transports and stirs the two-component developer composed of a carrier, and the transport unit includes a rotating support shaft and stirring blades provided on the support shaft. The image forming apparatus includes a large-diameter portion and a small-diameter portion having a smaller diameter than the large-diameter portion, and a plurality of the small-diameter portions are provided across the large-diameter portion.

  According to the present invention, in a conveying means having a rotating support shaft and a stirring blade provided on the support shaft, the support shaft has a large-diameter portion and a small-diameter portion whose diameter is smaller than the large-diameter portion. In addition, since a plurality of small-diameter portions are provided with the large-diameter portion interposed therebetween, in the developer conveyed by the conveying means, the position of the developer is high (the distance from the rotation center is long) and the developer By forming a plurality of portions whose positions are low (the distance from the rotation center is short), the stirrability of the developer can be improved.

  FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, a paper feeding unit 14 is provided below the image forming apparatus main body 12, and a first discharge tray 16 is provided on the upper surface of the image forming apparatus main body 12. Is formed. Further, a second discharge tray 18 is provided on the left side surface of the image forming apparatus main body 12 so as to face the first discharge tray 16, and a manual feed tray is provided at the lower part of the left side surface of the image forming apparatus main body 12. 20 is provided.

  The paper feed unit 14 includes a paper tray 22 on which paper is stacked, and a paper feed roll 24 that feeds paper from the paper tray 22, and the paper fed by the paper feed roll 24 is transported by the transport rolls 26 and 28. Through the sheet feed path 30 and sent to a transfer roll 74 described later, the developer image is transferred from the transfer roll 74, fixed by the fixing roll 32, and the first discharge tray according to the position selection of the switching claw 34. 16 or the second discharge tray 18 is selected and discharged by the discharge rolls 36 and 38. The first tray 16 discharges paper with the surface on which the developer image is fixed as the back surface, and the second tray 18 discharges paper with the surface on which the developer image is fixed as the front surface.

  However, in the case of double-sided printing, the discharge roll 36 is reversed and supplied to the reverse path 40 with respect to the sheet to be discharged from the first discharge tray 16, and again by the transport rolls 42, 44, 46, and 48. Returning to the paper feed path 30, the back side is printed. The paper in the manual feed tray 20 is supplied by the manual feed roll 49 and sent to the paper feed path 30 through the transport roll 48.

  The photoconductor unit 50 includes four photoconductors 52 as image carriers arranged in the vertical direction, and the photoconductors 52 are for yellow, magenta, black, and cyan, for example, from the top. Further, in this photoreceptor unit 50, a refresh roll 54 and a charging roll 56 are provided so as to rotate in contact with the photoreceptor 52, respectively.

  The developing unit 58 is arranged on the right side of the photoconductor unit 50, and four developing devices 60 are arranged in the vertical direction corresponding to the photoconductor 52. On the right side of the developing unit 58, an exposure unit 62 is disposed. From the exposure unit 62, four laser beams corresponding to image signals are emitted toward the photoconductor 52, and a latent image is formed on the photoconductor 52. It comes to form. Four toner cartridges 64 are arranged on the right side of the exposure unit 62. The toner cartridges 64 and the developing device 60 are connected via a developer supply path (not shown), and the developer is supplied from the toner cartridge 64 to the developing device. 60. Accordingly, the four developing devices 60 develop the latent images formed on the respective photoconductors 52 with the toner supplied from the respective toner cartridges 64.

  The intermediate transfer unit 66 is disposed on the left side of the photoreceptor unit 50 and includes three drum-shaped intermediate transfer members 68, 70, and 72. The two first intermediate transfer members 68 and 70 are arranged in the vertical direction, and the upper first intermediate transfer member 68 rotates in contact with the two photosensitive members 52 and 52 arranged at the upper portion, so that the lower first intermediate transfer member. 70 rotates in contact with the two photoconductors 52 and 52 disposed below. The second intermediate transfer member 72 rotates in contact with both the first intermediate transfer members 68 and 70, and the transfer roll 74 rotates in contact with the second intermediate transfer member 72. Accordingly, the two color toner images are transferred from the two photoconductors 52 and 52 to the first intermediate transfer bodies 68 and 70, respectively, and the two color toner images transferred to the first intermediate transfer bodies 68 and 70 are transferred to the first intermediate transfer bodies 68 and 70, respectively. 2 is transferred to the intermediate transfer body 72 to become four colors, and the toner images of these four colors are transferred onto the paper by the transfer roll 74. A cleaning roll 76 and a cleaning brush 78 are disposed on each of the intermediate transfer bodies 68, 70, and 72. The toner supplemented by the cleaning roll 76 is scraped off by, for example, a blade, and the scraped toner is illustrated in the drawing. Not collected in a collection container.

2 to 4, an example of the developing device 60 is shown.
As shown in FIG. 2, the developing device 60 has a developing device main body 80 and a magnet roll 82 that rotates in contact with the above-described photoreceptor 52, and the developing device main body 80 has two-component development composed of toner and carrier. For example, two augers (a first auger 86 and a second auger 88) are provided as conveying means for conveying the agent while stirring. The first auger 86 includes a first support shaft 90 that is rotatably supported by the developing device main body 80, and a first stirring blade 92 provided on the first support shaft 90. The first stirring blade 92 is spirally provided on the first support shaft 90. Similarly, the second auger 88 includes a second support shaft 94 that is rotatably supported by the developing device main body 80, and a second stirring blade 96 that is spirally provided on the second support shaft 94. Have

  As shown in FIG. 3, the two augers (the first auger 86 and the second auger 88) rotate in opposite directions and are partitioned by a partition wall 98 formed in the developing device main body 80. Connected via circulation ports 100, 100 formed near both ends, the developer that has entered the developing device main body 80 from the toner supply port 102 provided in the developing device main body 80 is contained in the developing device main body 80. It is circulated and supplied to the magnet roll 82 (shown in FIG. 2). That is, the developer in the developing device main body 80 is transported in the direction of the arrow in FIG. 3 (developer transport direction) as the first auger 86 and the second auger 88 rotate. Further, a developer discharge unit 104 is formed at one end of the developing device main body 80, and a part of the circulated developer is taken into the developer discharge unit 104. The developer that has entered the developer discharge unit 104 does not function in the developing action and is collected in a collection container (not shown).

  As shown in FIG. 3, the first support shaft 90 includes a large diameter portion 105 and a small diameter portion 106 having a diameter smaller than that of the large diameter portion 105, and the small diameter is sandwiched between the large diameter portions 105. A plurality of units 106 are provided. More specifically, the first support shaft 90 is provided with two small-diameter portions 106 (first small-diameter portion 106a and second small-diameter portion 106b), and the first small-diameter portion 106a is positioned downstream in the transport direction. The second small-diameter portion 106b is disposed at the end. The diameter (eg, d2 in FIG. 3) of the small diameter portion 106 is smaller than the large diameter portion 105 (eg, d1 in FIG. 3). As a result, the blade area of the first stirring blade 92 provided on the small diameter portion 106 of the first stirring blade 92 provided on the first support shaft 90 is equal to that of the first stirring blade 92 provided on the large diameter portion 105. The area of the blade of the stirring blade 92 is larger, and the developer in the small-diameter portion 106 is more stirred and transported reliably in the transport direction.

  Further, the toner supply port 102 to which toner is supplied from the above-described toner cartridge 64 (shown in FIG. 1) is provided to face the small diameter portion 106, and more specifically, above the first small diameter portion 106a in the gravity direction. The replenishing toner from the toner cartridge 64 falls to the position of the first small diameter portion 106a. Accordingly, since the capacity for holding the developer in the small diameter portion 106 is larger than the capacity for holding the developer in the large diameter portion 105, accumulation of developer around the toner supply port 102 (first small diameter portion 106a) is prevented. be able to.

The first support shaft 90 includes a large-diameter portion 105 on the upstream side in the developer conveyance direction (arrow direction in FIG. 3) of the small-diameter portion 106 and a large-diameter portion 105 on the downstream side in the developer conveyance direction of the small-diameter portion 106. For example, a paddle portion 108 is provided as a stirring member extending in the diameter direction of the first support shaft 90. Specifically, the first paddle portion 108a is provided in the large diameter portion 105 on the upstream side in the developer conveying direction of the first small diameter portion 106a, and the first small diameter portion 106a on the downstream side in the developer conveying direction. A second paddle portion 108 b is provided in the large diameter portion 105. That is, each paddle part 108 is provided on the upstream side in the developer conveyance direction from each small diameter part 106 (the first small diameter part 106a and the second small diameter part 106b). As shown in FIG. 4, the paddle portion 108 is provided with a plurality of (for example, four) groove portions 110 in the axial direction of the first support shaft 90.
With the above-described structure, the paddle unit 108 adjusts the transport amount of the developer. Specifically, the paddle 108 part weakens the developer transport force in the first stirring blade 92 by transporting the developer upstream of the paddle 108 part while reducing the amount of developer. The transport amount is reduced (restricted).
The paddle portion 108 may be a simple plate-shaped stirring member as well as a form in which the groove portion 110 is provided. Further, the first paddle portion 108a and the second paddle portion 108b are changed so that the number and shape of the groove portions 110 are different, and the conveying force (development) between the first paddle portion 108a and the second paddle portion 108b is developed. A difference may be generated in the amount of restriction of the agent.

  Further, the pitch of the first stirring blade 92 provided in the small diameter portion 106 of the first support shaft 90 is shorter than that of the first stirring blade 92 provided in the large diameter portion 105 of the first support shaft 90. It is formed to become. More specifically, the pitch of the first stirring blades 92 provided in the small diameter portion 106 (for example, p2 in FIG. 3) is the first stirring blade provided in the large diameter portion 105 of the first support shaft 90. The pitch is shorter than 92 (for example, p1 in FIG. 3).

As described above, the pitch of the first stirring blades 92 provided in the small-diameter portion 106 of the first stirring blades 92 provided in the first support shaft 90 is shortened, thereby providing the large-diameter portion 105. Compared with the first stirring blade 92, the number of turns of the first stirring blade 92 in the small-diameter portion 106 is increased, and the total area of the first stirring blade 92 over the entire small-diameter portion 106 is widened. Therefore, the developer is further stirred in the small diameter portion 106 and reliably conveyed in the conveyance direction. In addition, since the number of turns of the first stirring blade 92 in the small diameter portion 106 is increased, the small diameter portion 106 can be reinforced and the first support shaft 90 can be prevented from being bent due to insufficient strength.
When the first stirring blade 92 provided in the small diameter portion 106 is formed by one line as in this example, the pitch of the first stirring blade 92 provided in the small diameter portion 106 is It is preferable to set the level so that the developer conveyance speed is not lowered due to the shortening of the lead length of the first stirring blade 92.

  Further, the first stirring blade 92 provided in the small diameter portion 106 of the first support shaft 90 has a thickness larger than that of the first stirring blade 92 provided in the large diameter portion 105 of the first support shaft 90. It is formed to be thick. More specifically, the thickness (t2 in FIG. 3) of the first stirring blade 92 provided on the small diameter portion 106 of the first stirring blade 92 provided on the first support shaft 90 is large. The first stirring blade 92 provided in the portion 105 is formed thicker than the thickness (t1 in FIG. 3). As described above, the thickness of the first stirring blade 92 provided in the small diameter portion 106 is formed to be thicker than the thickness of the first stirring blade provided in the large diameter portion 105. The small diameter portion 106 of the support shaft 90 can be reinforced, and the first support shaft 90 can be prevented from being bent due to insufficient strength.

Next, the operation of the developing device 60 according to the above embodiment will be described.
When the replenishment toner is supplied from the toner cartridge 64 through the toner supply port 102, the replenishment toner is conveyed in the developer conveyance direction (arrow direction in FIG. 3) while being stirred together with the developer in the developing device main body 80. The

  The developer in the developing device main body 80 has a higher developer position at the position of the large-diameter portion 105 upstream of the first small-diameter portion 106a in the transport direction than the position of the small-diameter portion 106 (rotation center). The distance of the developer is lower (the distance from the rotation center is shorter) at the position of the first small diameter portion 106a than at the position of the large diameter portion 105. ) It is conveyed while maintaining the state. Further, the position of the large-diameter portion 105 on the downstream side in the transport direction from the first small-diameter portion 106a and the upstream side in the transport direction from the second small-diameter portion 106b, that is, the position of the large-diameter portion 105 provided with the second paddle portion 108b. Then, the developer is transported while maintaining a state where the position of the developer is high (the distance from the rotation center is long) as compared with the position of the small-diameter portion 106, and the large-diameter portion at the position of the second small-diameter portion 106 b. The developer is transported while maintaining the state where the developer position is low (the distance from the rotation center is short) as compared with the position of 105, and further, the large-diameter portion 105 on the downstream side in the transport direction from the second small-diameter portion 106b. In this position, as compared with the position of the small-diameter portion 106, the developer is transported while maintaining a higher position (longer distance from the rotation center). That is, at the position of each small diameter portion 106, the position of the developer decreases, that is, the distance from the rotation center of the developer decreases, and at the position of the large diameter portion 105, the position of the developer increases. The distance from the rotation center of the developer is long.

  As described above, the plurality of small-diameter portions 106 having a diameter smaller than that of the large-diameter portion 105 are provided on the first support shaft 90 with the large-diameter portion 105 interposed therebetween, whereby the developer position (distance from the rotation center). A plurality of high portions (peak portions) and low portions (valley portions) where the developer position (distance from the rotation center) is low can be formed alternately. Accordingly, since a difference in height occurs in the developer conveyed in the conveyance direction, the positions of the developers (vertical direction or position in the conveyance direction) are repeatedly switched, thereby improving the agitation of the developer. Can do. As a result, poor charging of the developer is suppressed, and a good image after development can be obtained.

  Further, the pitch of the first stirring blades 92 provided in the small-diameter portion 106 is made shorter than that of the first stirring blades 92 provided in the large-diameter portion 105, so that the total of the first stirring blades 92 in the small-diameter portion 106 is reduced. A portion (mountain portion) where the area is widened, the developer is more stirred and transported reliably in the transport direction, and the developer position (distance from the rotation center) in the developer transported in the transport direction is high The difference in height from the portion (valley portion) where the developer position (distance from the center of rotation) is low can be further increased, and the stirrability can be further improved.

  Further, the paddle part 108 is provided at a position upstream of the first small diameter part 106 in the conveyance direction and downstream of the conveyance direction, and the developer conveyance amount in the first small diameter part 106a and the second small diameter part 106b is adjusted. Thus, in the developer transported in the transport direction, the portion where the developer position (distance from the rotation center) is high (the peak portion) and the portion where the developer position (distance from the rotation center) is low (the valley portion) ) And the height difference can be further increased, and the stirrability can be further improved. Further, by providing paddle portions 108 on the upstream side and the downstream side in the transport direction of the toner supply port 102, the transport force (regulation) of the paddle portion 108 on the upstream side in the transport direction and the paddle portion 108 on the downstream side in the transport direction. (Specifically, the developer regulation amount is increased in the paddle portion 108a on the upstream side in the transport direction, and the developer regulation amount is reduced in the paddle portion 108b on the downstream side in the transport direction). In this case, toner accumulation around the toner supply port 102 can be further prevented.

Next, a second embodiment will be described.
FIG. 5 shows a developing device 60 according to the second embodiment.
As shown in FIG. 5, the 1st stirring blade 92 provided in the small diameter part 106 of the 1st support shaft 90 in 2nd Embodiment is formed in multiple stripes. Specifically, the first stirring blades 92 provided in the first small-diameter portion 106 a and the second small-diameter portion 106 b are formed, for example, in two strips, and the first stirring blade 92 provided in the large-diameter portion 105. The stirring blade 92 is formed of, for example, one strip.

  Further, the pitch of the first stirring blades 92 provided on the small-diameter portion 106 with two strips is shorter than that of the first stirring blades 92 provided on the large-diameter portion 105 with one strip. More specifically, the pitch (for example, p3 in FIG. 5) of the first stirring blades 92 provided in the small diameter portion 106 is the pitch (for example, FIG. 5) of the first stirring blades 92 provided in the large diameter portion 105. Shorter than p1). The lead length (for example, L2 in FIG. 5) of the first stirring blade 92 provided in the small diameter portion 106 and the lead length (for example, L1 in FIG. 5) of the first stirring blade 92 provided in the large diameter portion 105. Are the same, that is, L2 = L1.

Thus, the total area of the first stirring blades 92 in the small-diameter portion 106 is widened by forming the first stirring blades 92 provided in the small-diameter portion 106 in multiple lines (stacking the stirring blades). Therefore, the developer is further stirred in the small-diameter portion 106 and reliably transported in the transport direction, and the developer position (distance from the rotation center) in the developer transported in the transport direction is high (the peak portion). And the difference in height between the developer position (distance from the center of rotation) and the portion where the developer is low (valley portion) can be further enlarged, and the stirrability of the developer can be further improved.
Moreover, since the number of the first stirring blades 92 in the small diameter portion 106 increases by forming the first stirring blades 92 provided in the small diameter portion 106 in multiple lines (stacking the stirring blades), the small diameter portion 106 is increased. The first support shaft 90 can be prevented from bending due to insufficient strength.

  As described above, the present invention can be used for an image forming apparatus such as a copying machine, a facsimile apparatus, and a printer, and a developing apparatus.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. 1 is a longitudinal sectional view showing a developing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line AA of FIG. 2, showing the developing device according to the embodiment of the present invention. The paddle provided in the 1st auger used for the developing device concerning the embodiment of the present invention is shown, (a) is a side view and (b) is a BB line sectional view of (a). It is a cross-sectional view showing a developing device according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 60 Developing apparatus 86 1st auger 90 1st support shaft 92 1st stirring blade 102 Toner supply port 106 Small diameter part 108 Paddle part

Claims (8)

In a developing device that transports and agitates a two-component developer composed of a toner and a carrier by a transport means,
The conveying means includes a rotating support shaft and a stirring blade provided on the support shaft. The support shaft includes at least three large diameter portions and at least two diameters smaller than the large diameter portion . A developing device comprising: a small-diameter portion , wherein the small-diameter portion is provided between the large-diameter portions .   The developing device according to claim 1, wherein a toner supply port through which toner is supplied is provided opposite to the small diameter portion.   The developing device according to claim 1, wherein a stirring member extending in a diameter direction of the support shaft is provided in a large diameter portion of the small diameter portion upstream in the developer conveyance direction.   The developing device according to claim 1, wherein a stirring member extending in a diameter direction of the support shaft is provided in a large diameter portion of the small diameter portion downstream in the developer transport direction. In a developing device that transports and agitates a two-component developer composed of a toner and a carrier by a transport means,
The conveying means includes a rotating support shaft and a stirring blade provided on the support shaft. The support shaft includes at least three large diameter portions and at least two diameters smaller than the large diameter portion . A small-diameter portion, and the small- diameter portion is provided between the large-diameter portions, and the stirring blades provided in the small-diameter portion are formed in more lines than the stirring blades provided in the large-diameter portion. A developing device. In a developing device that transports and agitates a two-component developer composed of a toner and a carrier by a transport means,
The conveying means includes a rotating support shaft and a stirring blade provided on the support shaft. The support shaft includes at least three large diameter portions and at least two diameters smaller than the large diameter portion . A small-diameter portion, and the small- diameter portion is provided between the large-diameter portions, and the stirring blade provided in the small-diameter portion has a shorter pitch than the stirring blade provided in the large-diameter portion. A developing device. In a developing device that transports and agitates a two-component developer composed of a toner and a carrier by a transport means,
The conveying means includes a rotating support shaft and a stirring blade provided on the support shaft. The support shaft includes at least three large diameter portions and at least two diameters smaller than the large diameter portion . A small-diameter portion, the small-diameter portion is provided between the large-diameter portions, and the stirring blade provided in the small-diameter portion is thicker than the stirring blade provided in the large-diameter portion. A developing device. An image carrier on which a latent image is formed, and a developing device that develops the latent image formed on the image carrier;
The developer device has a conveying means for conveying and stirring a two-component developer composed of toner and a carrier,
The conveying means includes a rotating support shaft and a stirring blade provided on the support shaft. The support shaft includes at least three large diameter portions and at least two diameters smaller than the large diameter portion . An image forming apparatus comprising: a small-diameter portion , wherein the small-diameter portion is provided between the large-diameter portions .

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