JP7115178B2 - CONVEYING MECHANISM, DEVELOPING DEVICE, AND IMAGE FORMING APPARATUS - Google Patents

Description

The present invention relates to a conveying mechanism, a developing device, and an image forming apparatus.

Japanese Patent Application Laid-Open No. 2002-201003 discloses a configuration in which the spiral pitch of the take-in portion is shorter than the spiral pitch of the stirring portion in the agitating/conveying portion that has a spiral blade member and that conveys the developer.

Japanese Patent Application Laid-Open No. 2007-304202

Here, the conveying mechanism includes a shaft portion having a large-diameter portion with a large diameter partly in the axial direction, a first blade spirally formed on the outer peripheral surface of the large-diameter portion, and a a second blade helically formed on the outer peripheral surface of the portion immediately upstream of the radial portion; and a third blade helically formed on the outer peripheral surface of the portion upstream of the shaft portion immediately upstream of the shaft; A configuration is conceivable in which the powder is conveyed by the first blade, the second blade and the third blade by the rotation of the parts. In this configuration, a projecting portion projecting from the radially outer side of the large-diameter portion toward the large-diameter portion is further provided, and the powder conveyed downstream in the conveying direction of the large-diameter portion per one rotation of the shaft portion A configuration for quantifying the amount of transport of is conceivable.

In the configuration provided with the projecting portion, for example, when the number of rotations of the shaft portion increases, the powder does not stay on the upstream side of the large diameter portion in the conveying direction, and is moved downstream in the conveying direction by the large diameter portion and the projecting portion. Since the amount of powder whose movement is restricted is not stable, the amount of powder conveyed downstream in the conveying direction of the large-diameter portion per rotation of the shaft portion may fluctuate.

In the present invention, in both the first blade and the second blade, both the number of threads and the spiral pitch are the same as the number of threads and the spiral pitch of the third blade. It is an object of the present invention to suppress variation in the amount of powder conveyed per rotation of a shaft portion.

The invention of claim 1 comprises: a housing containing powder; a shaft disposed inside the housing and having a large-diameter portion having a large diameter in a part of the housing; A projecting portion formed on the inner wall and projecting toward the large-diameter portion from the radially outer side of the large-diameter portion, and a helical projection formed on the outer peripheral surface of the large-diameter portion and configured to move the powder by rotation of the shaft portion. A first blade for conveying the powder in one direction in the axial direction, and a helical shape formed on the outer peripheral surface of the portion of the shaft portion immediately upstream of the large-diameter portion. A second blade for conveying, and a third blade formed spirally on the outer peripheral surface of the upstream portion of the shaft portion relative to the immediately upstream portion and conveying the powder to the one side by rotation of the shaft portion. , At least one of the first blade and the second blade has a thread number and a spiral pitch that are smaller than those of the third blade.

In the invention of claim 2, at least one of the number of threads and the spiral pitch of both the first blade and the second blade is smaller than the number of threads and the spiral pitch of the third blade.

In the invention of claim 3, both the number of threads and the spiral pitch of both the first blade and the second blade are smaller than the number of threads and the spiral pitch of the third blade.

In the invention of claim 4, the outer diameter of the second blade is smaller than the outer diameter of the first blade.

In the invention of claim 5, the thickness of the second blade along the axial direction is greater than the thickness of the first blade along the axial direction.

In the sixth aspect of the invention, the length of the space between the blades along the axial direction of the second blade is shorter than the length of the space between the blades of the first blade along the axial direction.

In the invention of claim 7, the first blade is formed continuously with the second blade.

In the eighth aspect of the invention, the first blade is formed so as to reach the outer peripheral surface of the portion of the shaft portion that is directly downstream of the large diameter portion.

In the ninth aspect of the invention, the first blade reaches the downstream side of the downstream end of the projecting portion.

In the tenth aspect of the invention, the axial length of the projecting portion is greater than or equal to the axial length of the large-diameter portion.

In the eleventh aspect of the invention, at least one of the upstream end and the downstream end of the projecting portion extends further in the axial direction than at least one of the upstream end and the downstream end of the large diameter portion.

According to a twelfth aspect of the invention, there is provided a holding body arranged along the shaft portion above the immediately upstream portion and holding the powder stagnating in the immediately upstream portion on the outer periphery.

In the thirteenth aspect of the present invention, the second blade is arranged at least in a region from the center in the axial direction to the downstream end in the holding region where the holder holds the powder.

The invention according to claim 14 is the apparatus according to any one of claims 1 to 13, wherein the toner as the powder is replenished into the housing on the upstream side with respect to the large diameter portion, and the developer containing the toner is conveyed. and a supply body for supplying the developer conveyed by the conveying mechanism to the latent image.

A fifteenth aspect of the present invention is the conveying mechanism according to claim 12 or 13, wherein the conveying mechanism is replenished with the toner through a passage, and the holder conveys the held developer to the passage, The passage is closed with developer to stop the replenishment of the toner.

<16> A latent image holding member for holding a latent image; <14> or <15> for developing the latent image; and <16> for transferring the image developed by the developing device onto a recording medium. a transfer unit;

According to the configuration of claim 1 of the present invention, in both the first blade and the second blade, both the number of threads and the helical pitch are the same as the number of threads and the helical pitch of the third blade. It is possible to suppress fluctuations in the amount of powder conveyed per rotation of the shaft portion in the powder conveyed downstream in the conveying direction of the shaft portion.

According to the configuration of claim 2 of the present invention, in only one of the first blade and the second blade, at least one of the number of threads and the helical pitch is smaller than the number of threads and the helical pitch of the third blade, Fluctuations in the amount of powder conveyed per rotation of the shaft portion in the conveying direction downstream side of the large-diameter portion can be suppressed.

According to the configuration of claim 3 of the present invention, in both the first blade and the second blade, only one of the number of threads and the spiral pitch is larger than that of the third blade. Fluctuations in the amount of powder conveyed per rotation of the shaft portion can be suppressed in the powder that is conveyed to the downstream side in the conveying direction of the diameter portion.

According to the configuration of claim 4 of the present invention, compared to the configuration in which the outer diameter of the second blade is the same as the outer diameter of the first blade, the shaft portion in the powder conveyed downstream in the conveying direction of the large diameter portion It is possible to suppress fluctuations in the conveying amount per rotation of the motor.

According to the configuration of claim 5 of the present invention, compared to the configuration in which the thickness along the axial direction of the second blade is the same as the thickness along the axial direction of the first blade, the large-diameter portion is conveyed downstream in the conveying direction. It is possible to suppress fluctuations in the amount of powder conveyed per rotation of the shaft.

According to the sixth aspect of the present invention, the length of the space between the blades in the second blade along the axial direction is the same as the length of the space between the blades in the first blade along the axial direction. Compared to this, it is possible to suppress variation in the amount of powder conveyed per rotation of the shaft portion in the powder conveyed downstream in the conveying direction of the large-diameter portion.

According to the configuration of claim 7 of the present invention, it is possible to reduce the retention amount of the powder as compared with the configuration in which the first blade and the second blade are separated.

According to the configuration of claim 8 of the present invention, compared to the configuration in which the first blade is formed only on the large diameter portion, the powder conveyed downstream in the conveying direction of the large diameter portion per one rotation of the shaft portion Fluctuations in the amount of transport can be suppressed.

According to the configuration of claim 9 of the present invention, the downstream end of the first blade is conveyed downstream in the conveying direction of the large-diameter portion compared to the configuration in which the downstream end of the first blade is arranged upstream of the downstream end of the projecting portion. Fluctuations in the amount of powder conveyed per rotation of the shaft can be suppressed.

According to the configuration of claim 10 of the present invention, compared to the configuration in which the length of the projecting portion along the axial direction is less than the length of the large diameter portion along the axial direction, Fluctuations in the amount of powder conveyed to the side per rotation of the shaft portion can be suppressed.

According to the configuration of claim 11 of the present invention, compared to the configuration in which the projecting portion is arranged only in the range from the upstream end to the downstream end of the large diameter portion, the large diameter portion is conveyed downstream in the conveying direction. Fluctuations in the amount of powder conveyed per rotation of the shaft can be suppressed.

According to the twelfth aspect of the present invention, variation in the amount of powder held by the holder in the axial direction is suppressed compared to the case where the holder is arranged above only the upstream portion with respect to the immediately upstream portion. be.

According to the configuration of claim 13 of the present invention, the powder held by the holding part is less dense than when the second blade is arranged only in the region on the downstream end side of the axial center in the holding region of the holding body. Variation in the axial direction of the retained amount is suppressed.

According to the configuration of claim 14 of the present invention, in both the first blade and the second blade, both the number of threads and the spiral pitch are the same as the number of threads and the spiral pitch of the third blade. In comparison, fluctuations in the toner density of the developer can be suppressed.

According to the fifteenth aspect of the present invention, compared to a configuration in which the holding member is provided with a conveying mechanism arranged only above the upstream portion with respect to the immediately upstream portion, the retention amount of the developer retained in the passage in the axial direction is Variation is suppressed.

According to the sixteenth aspect of the present invention, the developing device has a conveying mechanism in which the number of threads and the spiral pitch of both the first blade and the second blade are the same as the number of threads and the spiral pitch of the third blade. Poor image quality can be suppressed compared to the configuration provided with

1 is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment; FIG. 2 is a plan view showing the developing device according to the present embodiment with the upper wall of the housing omitted; FIG. 2 is a front cross-sectional view showing the configuration of the developing device according to the embodiment; FIG. It is a side view which shows the structure of the stirring auger which concerns on this embodiment. It is a perspective view which expands a part and shows the structure of the stirring auger which concerns on this embodiment. 4 is a side cross-sectional view (a cross-sectional view taken along line 6-6 in FIG. 3) showing a part of the developing device according to the present embodiment; FIG.

An example of an embodiment according to the present invention will be described below with reference to the drawings.

An arrow UP shown in the drawing indicates the upper side (vertically upward) of the apparatus, and an arrow DO indicates the lower side (vertically downward) of the apparatus. An arrow LH shown in the drawing indicates the left side of the device, and an arrow RH indicates the right side of the device. An arrow FR shown in the drawing indicates the front of the device, and an arrow RR indicates the rear of the device. Since these directions are defined for convenience of explanation, the configuration of the apparatus is not limited to these directions.

Moreover, the directions along the upper and lower sides of the device may be referred to as the vertical direction of the device. Also, the directions along the left and right sides of the device may be referred to as left-right directions of the device. The lateral direction of the device is also the width direction (horizontal direction) of the device. Also, the directions along the front and rear of the device may be referred to as the front-rear direction of the device. The front-rear direction of the device is also the depth direction (horizontal direction) of the device. Note that the word “device” may be omitted in each direction of the device. That is, for example, "above the device" may be simply referred to as "above".

In addition, the symbol in which "x" is described in "o" in the figure means an arrow pointing from the front to the back of the paper surface. In addition, the symbol "·" written in the "o" in the drawing means an arrow pointing from the back to the front of the paper surface.

<Image forming apparatus 10>
First, the image forming apparatus 10 according to this embodiment will be described. FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 10. As shown in FIG.

As shown in FIG. 1, the image forming apparatus 10 includes a paper storage unit 12 that stores paper P, a transport unit 14 that transports paper P, and an image forming unit 16 that forms an image on paper P. I have.

(Paper storage unit 12)
The paper storage unit 12 is provided with a storage member 12A that can be pulled forward from the housing 10A of the image forming apparatus 10, and the paper P is stacked on the storage member 12A. Further, the paper storage unit 12 is provided with a delivery roll 14B that delivers the paper P stacked in the storage member 12A to the transport path 14A that constitutes the transport unit 14. As shown in FIG. Here, the paper P is an example of a recording medium.

(Conveyor 14)
The transport unit 14 includes a delivery roll 14B that delivers the paper P from the storage member 12A along the transport path 14A, and a plurality of transport rolls 14C that transport the paper P to the paper discharge unit 10B via the image forming unit 16. , is equipped with

(Image forming section 16)
The image forming section 16 has an image forming unit 18 that forms a black toner image. The image forming unit 18 includes a photoreceptor drum 20 as an example of a latent image holder that holds a latent image, an exposure device 26 , a charging roll 24 as a charging device, and a developing device 30 .

In the image forming unit 18 , the charging roll 24 charges the photosensitive drum 20 . Further, the exposure device 26 exposes the photosensitive drum 20 charged by the charging roll 24 to form an electrostatic latent image (an example of a latent image). The developing device 30 develops the electrostatic latent image formed on the photosensitive drum 20 by the exposure device 26 to form a toner image (an example of an image). A specific configuration of the developing device 30 will be described later.

Further, the image forming unit 16 includes a transfer roller 22 as an example of a transfer unit that transfers the toner image developed by the developing device 30 onto the paper P, and a fixing device 28 that fixes the toner image onto the paper P by heat and pressure. and have.

[Developing device 30]
Next, the developing device 30 will be described with reference to FIGS. 2 to 6. FIG.

2 and 3, the developing device 30 includes a transport mechanism 31 that transports the developer G containing the toner TN, and the developer G transported by the transport mechanism 31 onto the photosensitive drum 20 as an electrostatic latent image. and a replenishment mechanism 39 that replenishes the toner TN to the transport mechanism 31 .

As shown in FIG. 3, the transport mechanism 31 includes a housing 32, a supply auger 38 for supplying the developer G to the developing roll 34, an agitating auger 90 for agitating the developer G, an overhanging portion 80, It has The developer G in this embodiment is a two-component developer composed of toner TN and magnetic carrier as main components. Here, the toner TN and the developer G are examples of powder.

Specific configurations of each part of the transport mechanism 31 (the housing 32, the supply auger 38, the agitating auger 90, and the protruding part 80), the developing roller 34, and the replenishment mechanism 39 will be described below.

[Case 32]
The housing 32 contains developer G, as shown in FIG. The housing 32 is arranged next to (on the left side of) the photoreceptor drum 20. In the housing 32, a portion facing the photoreceptor drum 20 has an opening 32A that opens the interior of the housing 32 in the front-rear direction. It is formed extending to Further, on the opposite side of the photosensitive drum 20 across the opening 32A, a transfer path 32B in which the developing roll 34 is arranged is formed extending in the front-rear direction.

Further, a supply path 32D in which a supply auger 38 is arranged is formed extending in the front-rear direction, obliquely below the delivery path 32B. Further, on the opposite side of the delivery path 32B across the supply path 32D, a stirring path 32C in which a stirring auger 90 is arranged is formed extending in the front-rear direction.

Moreover, the wall surface forming the supply path 32D and the stirring path 32C has a U-shaped cross section, as shown in FIG. Furthermore, a partition wall 32E is formed between the supply path 32D and the stirring path 32C to partition the supply path 32D and the stirring path 32C.

As shown in FIG. 2, in the housing 32, a supply auger 38 is arranged from the front side to the rear side of the supply path 32D. 2, only the left and right ends of the supply auger 38 are shown.

A stirring auger 90 is arranged from the front side to the rear side of the stirring passage 32C. The agitation path 32C and the supply path 32D are connected at their front ends and at their rear ends, respectively, and the developer G is configured to circulate through the agitation path 32C and the supply path 32D. The partition wall 32E is arranged in the front-rear direction between the connecting portion at the front end and the connecting portion at the rear end of the stirring passage 32C and the supply passage 32D.

[Development roll 34]
The developing roll 34 is arranged in the delivery path 32B as shown in FIG. The developing roll 34 faces the photosensitive drum 20 through the opening 32A of the housing 32. As shown in FIG. A gap (development gap) is formed between the developing roll 34 and the photoreceptor drum 20 for transferring the developer G from the developing roll 34 to the photoreceptor drum 20 .

The developing roll 34 includes a magnet roll 34A having a circular cross section, and a rotating sleeve 34B that covers the magnet roll 34A and rotates around the magnet roll 34A.

The rotary sleeve 34B is rotated in the direction of an arrow A (clockwise) in the drawing by a torque transmitted from a drive source (not shown).

[Supply auger 38]
A feed auger 38 is positioned in the feed line 32D as shown in FIG. That is, the supply auger 38 is arranged inside the housing 32 . The supply auger 38 functions as a conveying member that conveys the developer G in the supply path 32D. Specifically, the supply auger 38 has a function of conveying the developer G from the rear side to the front side. Therefore, in the supply path 32D, the rear side is the upstream side in the developer G transport direction, and the front side is the downstream side in the developer G transport direction. In some cases, the "upstream side in the transport direction" is simply referred to as the "upstream side", and the "downstream side in the transport direction" is simply referred to as the "downstream side".

The supply auger 38 includes a supply shaft 38A extending in the front-rear direction and spiral supply blades 38B formed on the outer peripheral surface of the supply shaft 38A. Both ends of the supply shaft 38A are rotatably supported by the walls of the housing 32, and the supply shaft 38A is rotated by a drive source (not shown).

In this configuration, the rotating supply auger 38 supplies the developer G to the developing roll 34 while conveying the developer G in the supply path 32D from the rear side (upstream side) to the front side (downstream side). ing. Further, the rotating supply auger 38 delivers the developer G transported downstream (forward) of the supply path 32D to the stirring auger 90 of the stirring path 32C on the upstream (forward) side of the stirring path 32C.

[Stirring auger 90]
The stirring auger 90 is arranged in the stirring passage 32C, as shown in FIGS. That is, the stirring auger 90 is arranged inside the housing 32 . The stirring auger 90 functions as a conveying member that conveys the developer G in the stirring passage 32C. Specifically, the stirring auger 90 has a function of conveying the developer G from the front side to the rear side. Therefore, in the stirring path 32C, the front side is the upstream side in the developer G transport direction, and the rear side is the downstream side in the developer G transport direction.

Specifically, as shown in FIG. 4, the stirring auger 90 includes a stirring shaft 98, a first blade 91, a second blade 92, a third blade 93, a fourth blade 94, and a pair of protrusions. It has a portion 99 and a fifth blade 95 (see FIG. 2). Note that the stirring shaft 98 is an example of a shaft portion.

The stirring auger 90 rotates the stirring shaft 98 by a drive source (not shown), thereby rotating the first blade 91 , the second blade 92 , the third blade 93 , the fourth blade 94 , the pair of projecting portions 99 and the third blade. The five blades 95 convey while stirring the toner TN replenished from the replenishment mechanism 39 to the agitation path 32C and the developer G from the supply path 32D.

Hereinafter, the specific configuration of each part of the stirring auger 90 (the stirring shaft 98, the first blade 91, the second blade 92, the third blade 93, the fourth blade 94, the pair of protrusions 99 and the fifth blade 95) will be described. do.

<Stirring shaft 98>
The stirring shaft 98 is arranged along the longitudinal direction of the stirring path 32C, as shown in FIG. That is, the stirring shaft 98 is arranged along the front-rear direction inside the housing 32 . Both ends of the stirring shaft 98 in the axial direction are rotatably supported by the walls of the housing 32 . The stirring shaft 98 is rotated in one direction (counterclockwise direction in FIG. 3) by a rotational force transmitted from a drive source (not shown).

Furthermore, as shown in FIGS. 2 and 4, the stirring shaft 98 has a large-diameter portion 98A that is partially enlarged in the axial direction. Specifically, the large-diameter portion 98A has a larger diameter than the other portion of the stirring shaft 98 . In addition, the large diameter portion 98A is provided coaxially with other portions.

Since the large-diameter portion 98A protrudes radially outward of the stirring shaft 98, the upstream end and the downstream end of the large-diameter portion 98A in the conveying direction, as shown in FIG. An upstream end face 98X facing (forward) and a downstream end face 98Y facing downstream (backward) in the transport direction are formed. As shown in FIG. 6, the large-diameter portion 98A is arranged on the rear side (downstream side in the transport direction) with respect to the rotating roll 50, which will be described later, in the front-rear direction (the transport direction in the stirring path 32C). The outer diameter of the stirring shaft 98 is, for example, 9 mm at the large diameter portion 98A and 6 mm at other portions. That is, the outer diameter of the large diameter portion 98A is, for example, 1.5 times the outer diameter of the other portions. Moreover, the dimension along the radial direction of the stirring shaft 98 at the upstream end face 98X and the downstream end face 98Y is, for example, 1.5 mm. 6 shows side cross-sections of the housing 32 and the projecting portion 80, and also shows side surfaces of the stirring auger 90 and the rotating roll 50. As shown in FIG.

Further, as shown in FIG. 4, the stirring shaft 98 has a portion 98B immediately upstream of the large diameter portion 98A. The immediately upstream portion 98B is a portion of the stirring shaft 98 provided continuously with the large diameter portion 98A on the upstream side of the large diameter portion 98A in the direction in which the developer G is conveyed. Further, the immediately upstream portion 98B is set in a partial range of the upstream portion of the stirring shaft 98 with respect to the large diameter portion 98A in the conveying direction. The axial length of the immediately upstream portion 98B is longer than the axial length of the large diameter portion 98A, for example, 1.5 times or less of the axial length of the large diameter portion 98A.

Further, the stirring shaft 98 has an upstream portion 98C with respect to the immediately upstream portion 98B. The upstream portion 98C is a portion of the agitating shaft 98 that is provided on the upstream side of the developer G conveying direction with respect to the immediately upstream portion 98B and continues to the immediately upstream portion 98B. Note that the axial length of the upstream portion 98C is longer than the axial length of the immediately upstream portion 98B.

Further, the stirring shaft 98 has a portion 98D directly downstream from the large diameter portion 98A. The direct downstream portion 98D is a portion of the stirring shaft 98 provided continuously with the large diameter portion 98A downstream of the large diameter portion 98A in the direction in which the developer G is conveyed. In addition, the direct downstream portion 98D is set in a partial range of the downstream portion of the stirring shaft 98 with respect to the large diameter portion 98A in the conveying direction. The axial length of the directly downstream portion 98D is shorter than the axial length of the large diameter portion 98A.

The agitation shaft 98 also has a downstream portion 98E relative to a direct downstream portion 98D. The downstream portion 98E is a portion of the agitating shaft 98 provided continuously with the immediately downstream portion 98D on the downstream side of the developer G conveying direction with respect to the immediately downstream portion 98D. The axial length of the downstream portion 98E is longer than any of the axial length of the immediately downstream portion 98D, the axial length of the large diameter portion 98A, and the upstream portion 98C.

<First blade 91>
As shown in FIG. 4, the first blade 91 is spirally formed on the outer peripheral surface of the large diameter portion 98A. The first blade 91 conveys the developer G rearward (one example in the axial direction) by the rotation of the stirring shaft 98 .

In other words, the first blade 91 is wound around the stirring shaft 98 in a direction opposite to the rotating direction of the stirring shaft 98 toward one axial direction of the stirring shaft 98 . Specifically, the first blade 91 is wound rearward around the stirring shaft 98 in a clockwise direction as viewed rearward.

Furthermore, the first blade 91 is formed so as to reach the outer peripheral surface of the immediately downstream portion 98</b>D of the stirring shaft 98 . In other words, the first blade 91 conveys the developer G rearward beyond the large diameter portion 98A. In addition, the first blade 91 becomes longer in the radial direction in the direct downstream portion 98</b>D as the outer diameter of the stirring shaft 98 becomes smaller.

Further, as shown in FIG. 6 , the first blade 91 reaches the downstream side (rear side) of the downstream end (the downstream end face 84 described later) of the projecting portion 80 . In other words, the first blade 91 conveys the developer G rearward beyond the downstream end of the projecting portion 80 .

As shown in FIG. 4, the first blade 91 is specifically composed of a single blade. A spiral pitch P1 of the first blade 91 is, for example, 8 mm. The outer diameter D1 of the first blade 91 is, for example, 12 mm.

The helical pitch refers to the axial length per 360 degrees (one turn) in the circumferential direction of the stirring shaft 98 in the blades.

The first blade 91 is formed, for example, in a range of 360 degrees in the circumferential direction of the stirring shaft 98 at the large diameter portion 98A of the stirring shaft 98 . That is, the first blades 91 are formed within the range of one pitch at the large diameter portion 98A of the stirring shaft 98 . In other words, the large-diameter portion 98A of the stirring shaft 98 has an axial length of one pitch of the first blades 91 .

Further, the first blade 91 is formed, for example, in a range of 180 degrees in the circumferential direction of the stirring shaft 98 at the immediately downstream portion 98D of the stirring shaft 98 . That is, the first blades 91 are formed in the range of a half pitch (0.5 pitch) in the immediately downstream portion 98D of the stirring shaft 98. As shown in FIG. In other words, the immediately downstream portion 98D of the stirring shaft 98 has an axial length of 0.5 pitches of the first blades 91 .

The portion of the first blade 91 formed at the large diameter portion 98A of the stirring shaft 98 is regarded as the first blade 91, and the portion of the first blade 91 formed at the portion 98D immediately downstream of the stirring shaft 98 is the sixth blade. It may be grasped as a blade (another blade). In this case, the sixth blade is grasped as, for example, a blade formed continuously with the first blade 91 and having the same diameter and pitch as the first blade 91 .

<Second blade 92>
The second blade 92 is spirally formed on the outer peripheral surface of the immediately upstream portion 98B of the stirring shaft 98, as shown in FIG. The second blade 92 conveys the developer G rearward (one example in the axial direction) by the rotation of the stirring shaft 98 .

In other words, the second blade 92 is wound around the stirring shaft 98 in a direction opposite to the rotating direction of the stirring shaft 98 toward one axial direction of the stirring shaft 98 . Specifically, the second blade 92 is wound rearward around the stirring shaft 98 in a clockwise direction as viewed rearward. In other words, the second blade 92 is spirally wound in the same direction as the first blade 91 .

The second blade 92 is formed continuously with the first blade 91 as shown in FIG. That is, the first blade 91 is formed continuously with the second blade 92 . In other words, the front end (upstream end) of the first blade 91 and the rear end (downstream end) of the second blade 92 are connected. In other words, the developer G conveyed by the second blade 92 continues to be conveyed by the first blade 91 . In addition, in FIG. 5, the connection portion between the first blade 91 and the second blade 92 is indicated by reference numeral 912. As shown in FIG.

As shown in FIG. 4, the second blade 92 is specifically composed of a single blade. A spiral pitch P2 of the second blade 92 is, for example, 8 mm. The outer diameter D2 of the second blade 92 is, for example, 10 mm. The second blade 92 is formed, for example, in a range of 540 degrees in the circumferential direction of the stirring shaft 98 . That is, the second blade 92 is formed within a range of 1.5 pitches. In other words, the immediately upstream portion 98B of the stirring shaft 98 has an axial length of 1.5 pitches of the second blades 92 . The relationship between the number of blades, the spiral pitch, the outer diameter, etc. of the stirring auger 90 will be described later.

<Third blade 93>
The third blade 93 is spirally formed on the outer peripheral surface of the upstream portion 98C of the stirring shaft 98, as shown in FIG. The third blade 93 conveys the developer G backward by the rotation of the stirring shaft 98 .

Specifically, the third blade 93 is composed of a plurality of blades. More specifically, the third blade 93 is composed of two blades 93A and 93B. Therefore, in the third blade 93, the rotation of the stirring shaft 98 causes the two blades 93A and 93B to transport the developer G backward.

In other words, the blades 93A and 93B are wound around the stirring shaft 98 in a direction opposite to the rotational direction of the stirring shaft 98 toward one axial direction of the stirring shaft 98 . Specifically, the blades 93A and 93B are wound rearward around the stirring shaft 98 in a clockwise direction as viewed rearward. In other words, the blades 93A and 93B have a spiral shape wound in the same direction as the first blade 91 and the second blade 92 .

Further, the downstream end (rear end) of the third blade 93 is separated from the upstream end (front end) of the second blade 92 . Specifically, the third blade 93 is spaced apart from the second blade 92 in the circumferential and axial directions of the stirring shaft 98 . In other words, the third blade 93 has gaps in the circumferential direction and the axial direction with respect to the second blade 92 .

A spiral pitch P3 of the blades 93A and 93B is, for example, 24 mm. The outer diameter D3 of the blades 93A and 93B is, for example, 12 mm.

<Fourth blade 94>
The fourth blade 94 is formed on the outer peripheral surface of the downstream portion 98E of the stirring shaft 98, as shown in FIG. The fourth blade 94 conveys the developer G backward by the rotation of the stirring shaft 98 .

The fourth blade 94 is specifically composed of a plurality of blades. More specifically, the fourth blade 94 is composed of two blades 94A and 94B. A plurality (for example, nine) of the fourth blades 94 are arranged in the axial direction of the stirring shaft 98 .

Therefore, in the fourth blade 94, the rotation of the stirring shaft 98 causes the plurality of two blades 94A and 94B to convey the developer G backward. In other words, the blades 94A and 94B are wound around the stirring shaft 98 in a direction opposite to the rotational direction of the stirring shaft 98 toward one axial direction of the stirring shaft 98 . Specifically, the blades 94A and 94B are wound rearward around the stirring shaft 98 in a clockwise direction as viewed rearward. In other words, the blades 94A and 94B are spiral wound in the same direction as the first blade 91, the second blade 92 and the third blade 93.

Each of the blades 94A and 94B arranged in the axial direction of the stirring shaft 98 has an upstream end (front end) and a downstream end (rear end) separated from each other. Specifically, the blades 94A and 94B are arranged continuously in the axial direction of the stirring shaft 98 while being spaced apart in the circumferential direction of the stirring shaft 98 . In other words, the blades 94A and 94B have a gap in the circumferential direction of the stirring shaft 98 and are arranged without a gap in the axial direction of the stirring shaft 98 . It should be noted that each blade 94A, 94B may have a gap in the axial direction as long as the conveyance of the developer G is not hindered (the developer G cannot be accumulated).

The upstream end (front end) of the fourth blade 94 is separated from the downstream end (rear end) of the first blade 91 . Specifically, the fourth blade 94 is arranged continuously in the axial direction of the stirring shaft 98 while being separated from the first blade 91 in the circumferential direction of the stirring shaft 98 . In other words, the fourth blade 94 has a gap in the circumferential direction of the stirring shaft 98 and is arranged without a gap in the axial direction of the stirring shaft 98 with respect to the first blade 91 . The fourth blade 94 may have a gap in the axial direction with respect to the first blade 91 as long as the conveyance of the developer G is not hindered (the developer G cannot be accumulated).

Each blade 94A, 94B of the fourth blade 94 is formed, for example, in a range of 360 degrees in the circumferential direction of the stirring shaft 98. As shown in FIG. That is, each blade 94A, 94B is formed within a range of one pitch. A spiral pitch P4 of each blade 94A, 94B is, for example, 24 mm. An outer diameter D4 of the blades 94A and 94B is set to 12 mm, for example.

<Protrusion 99>
A pair of protrusions 99 are formed on the outer peripheral surface of the downstream portion 98E of the stirring shaft 98, as shown in FIG. The pair of protrusions 99 protrude radially outward from the stirring shaft 98 . Furthermore, the pair of protruding portions 99 also protrude radially outward from the stirring shaft 98 on the side opposite to the position shown in FIG. 4 and the like. The pair of protrusions 99 are arranged at predetermined intervals in the axial direction of the stirring shaft 98 . The pair of projecting portions 99 are arranged, for example, at an interval corresponding to two pitches of the fourth blades 94 .

<Fifth blade 95>
As shown in FIG. 2, the fifth blade 95 is spirally formed on the outer peripheral surface of the downstream end (rear end) of the stirring shaft 98 in the conveying direction. The fifth blade 95 has a spiral shape that is reversely wound to the first blade 91 , the second blade 92 , the third blade 93 and the fourth blade 94 . The fifth blade 95 conveys the developer G forward as the stirring shaft 98 rotates. The fifth blade 95 suppresses retention of the developer G at the downstream end (rear end) of the stirring path 32C and promotes movement of the developer G from the stirring path 32C to the supply path 32D.
<Relationship between number of threads and spiral pitch in each blade>
Here, at least one of the first blade 91 and the second blade 92 shown in FIG. Specifically, both the first blade 91 and the second blade 92 have at least one of the number of threads and the spiral pitch smaller than the number of threads and the spiral pitch of the third blade 93 . More specifically, both the first blade 91 and the second blade 92 have both the number of threads and the spiral pitch smaller than the number of threads and the spiral pitch of the third blade 93 . A specific configuration will be described below for each of the relationship between the number of blades and the relationship between the helical pitches of the blades.

<Relationship between the number of threads of each blade>
The number of rows of the first blade 91 and the second blade 92 shown in FIG. 4 is less (smaller) than the number of rows of the third blade 93 . Specifically, the number of rows of the first blade 91 and the number of rows of the second blade 92 are the same and smaller than the number of rows of the third blade 93 . More specifically, the number of rows of the first blade 91 and the number of rows of the second blade 92 are set to be one row smaller than the number of rows of the third blade 93 . More specifically, as described above, the third blade 93 is composed of, for example, two streaks, while the first and second blades 91 and 92 are composed of, for example, one streak.

The number of rows of the first blade 91 and the number of rows of the second blade 92 should be less than the number of rows of the third blade 93, and the number of rows of the first blade 91 and the number of rows of the second blade 92 may be different. good. Moreover, the number of threads of the first blade 91 and the second blade 92 should be less than the number of threads of the third blade 93 , and may be two or more less than the number of threads of the third blade 93 . Moreover, the number of threads of the first blade 91 and the second blade 92 may be less than the number of the third blade 93, and may be plural.

Furthermore, the number of rows of the first blade 91 and the number of rows of the second blade 92 are smaller than the number of rows of the fourth blade 94 . More specifically, the number of rows of the first blade 91 and the number of rows of the second blade 92 are one row less than the number of rows of the fourth blade 94 . More specifically, as described above, the fourth blade 94 is composed of, for example, two streaks, while the first and second blades 91 and 92 are composed of, for example, one streak. The number of threads of the third blade 93 and that of the fourth blade 94 are the same.

<Relationship between helical pitches of each blade>
The spiral pitch P1 of the first blade 91 and the spiral pitch P2 of the second blade 92 shown in FIG. 4 are smaller than the spiral pitch P3 of the blades 93A and 93B of the third blade 93. As shown in FIG. Specifically, the helical pitch P1 of the first blade 91 and the helical pitch P2 of the second blade 92 are the same and smaller than the helical pitch P3 of the blades 93A and 93B of the third blade 93 . More specifically, as described above, the spiral pitch P3 of the blades 93A and 93B of the third blade 93 is, for example, 24 mm, while the spiral pitch P1 of the first blade 91 and the second blade 92 The spiral pitch P2 of each is set to, for example, 8 mm.

The spiral pitch P1 of the first blade 91 and the spiral pitch P2 of the second blade 92 may be smaller than the spiral pitch P3 of the blades 93A and 93B of the third blade 93. The helical pitch P2 of the blades 92 may be different.

Also, the spiral pitch P1 of the first blade 91 and the spiral pitch P2 of the second blade 92 are smaller than the spiral pitch P4 of the blades 94A and 94B of the fourth blade 94 . More specifically, as described above, the spiral pitch P4 of the blades 94A and 94B of the fourth blade 94 is, for example, 24 mm, whereas the spiral pitch P1 of the first blade 91 and the second blade The spiral pitch P2 of 92 is set to 8 mm, for example. The spiral pitch P3 of the blades 93A and 93B of the third blade 93 and the spiral pitch P4 of the blades 94A and 94B of the fourth blade 94 are the same.

<Relationship between outer diameters of each blade>
The outer diameter D2 of the second blade 92 shown in FIG. 4 is made smaller than the outer diameter D1 of the first blade 91 . Specifically, the outer diameter D2 of the second blade 92 is larger than the outer diameter of the large diameter portion 98A of the stirring shaft 98 and smaller than the outer diameter D1 of the first blade 91 . More specifically, as described above, the outer diameter D1 of the first blade 91 is 12 mm, and the outer diameter of the large diameter portion 98A of the stirring shaft 98 is 9 mm. has an outer diameter D2 of 10 mm.

In addition, the second dimension along the radial direction of the second blade 92 is larger than the first dimension along the radial direction of the first blade 91 . Specifically, the first dimension is, for example, 1.5 mm (the radius of the first blade 91 is 6 mm - the radius of the large diameter portion 98A is 4.5 mm), while the second dimension is, for example, 2 mm (the The radius of the two blades 92 is 5 mm - the radius of the stirring shaft 98 is 3 mm).

The outer diameter D2 of the second blade 92 is smaller than the outer diameter D3 of the third blade 93 and the outer diameter D4 of the fourth blade 94 . More specifically, as described above, the outer diameter D3 of the third blade 93 and the outer diameter D4 of the fourth blade 94 are 12 mm, while the outer diameter D2 of the second blade 92 is 10 mm. It is said that Thus, the outer diameter D1 of the first blade 91, the outer diameter D3 of the third blade 93, and the outer diameter D4 of the fourth blade 94 are the same.

<Relationship between the thicknesses of the first blade 91 and the second blade 92>
As shown in FIG. 4, the thickness T2 of the second blade 92 along the axial direction of the stirring shaft 98 is greater than the thickness T1 of the first blade 91 along the axial direction. Specifically, when comparing at least the thickness T1 of a portion of the first blade 91 in the radial direction and the thickness T2 of a portion of the second blade 92 in the radial direction, the thickness T2 of the second blade 92 is thicker than the thickness T1 of the first blade 91 . In the present embodiment, the thickness T2 at the radially outer end of the second blade 92 is greater than the thickness T1 at the radially outer end of the first blade 91 . Furthermore, the thickness T2 at the radially inner end of the second blade 92 is also greater than the thickness T1 at the radially inner end of the first blade 91 .

<Relationship of space between blades in first blade 91 and second blade 92>
In the second blades 92 , the length of the space between the blades along the axial direction of the stirring shaft 98 is shorter than the length of the space between the blades of the first blade 91 along the axial direction. Specifically, as shown in FIG. 4, when the agitating auger 90 is viewed in its radial direction (for example, left-right direction), the length L2 along the axial direction of the space between the blades constituting the second blade 92 is , the length L1 of the space between the blades forming the first blade 91 along the axial direction. The length L2 corresponds to the length from the rear surface of the first blade that constitutes the second blade 92 to the front surface of the second blade (the blade on the rear side of the first blade). The length L1 corresponds to the length from the rear surface of the first blade that constitutes the first blade 91 to the front surface of the second blade (the blade on the rear side of the first blade).

Specifically, at least the length L2 of a portion of the second blade 92 in the radial direction is shorter than the length L1 of a portion of the first blade 91 in the radial direction. In this embodiment, the length L2 of the space at the radially outer end of the second blade 92 is shorter than the length L1 of the space at the radially outer end of the first blade 91 . Furthermore, the length L2 of the space at the radially inner end of the second blade 92 is also shorter than the length L1 of the space at the radially inner end of the first blade 91 .

[Overhanging portion 80]
As shown in FIGS. 3 and 6, the projecting portion 80 is formed on the inner wall of the housing 32 and projects from the radially outer side of the large diameter portion 98A of the stirring shaft 98 toward the large diameter portion 98A. there is Specifically, as shown in FIG. 3 , the projecting portion 80 projects from the radially outer side of the large-diameter portion 98A toward the large-diameter portion 98A at a portion of the large-diameter portion 98A in the circumferential direction. . More specifically, the protruding portion 80 protrudes downward from the upper wall 32X of the housing 32 toward the large diameter portion 98A. More specifically, the lower surface of the projecting portion 80 (the surface facing the large diameter portion 98A) is formed in an arc shape along the outer peripheral surface of the large diameter portion 98A when viewed in the axial direction of the stirring shaft 98. there is

In other words, the protruding portion 80 has a function of narrowing the passage width of the stirring passage 32C in the large diameter portion 98A and its periphery. Furthermore, the protruding portion 80 has a function of reducing the volume (capacity) of the large-diameter portion 98A and the agitation passage 32C around it.

As shown in FIG. 6, the upstream end and downstream end of the overhanging portion 80 in the conveying direction are respectively provided with an upstream end surface 82 facing the upstream side (forward side) in the conveying direction and a downstream side (rear side) in the conveying direction. ) is formed.

The axial length of the projecting portion 80 is greater than or equal to the axial length of the large diameter portion 98A. Specifically, the axial length of the projecting portion 80 is longer than the axial length of the large diameter portion 98A.

Furthermore, at least one of the upstream end and the downstream end of the protruding portion 80 axially extends beyond at least one of the upstream end and the downstream end of the large diameter portion 98A. Specifically, one of the upstream end and the downstream end of the projecting portion 80 axially extends beyond one of the upstream end and the downstream end of the large diameter portion 98A. More specifically, only the upstream end of the projecting portion 80 extends forward beyond the upstream end of the large diameter portion 98A. That is, the upstream end face 82 of the projecting portion 80 is arranged upstream (forward) of the upstream end face 98X of the large diameter portion 98A. The downstream end of the projecting portion 80 does not extend further rearward than the downstream end of the large diameter portion 98A, and the downstream end surface 84 of the projecting portion 80 is arranged along the downstream end surface 98Y of the large diameter portion 98A. there is In other words, the downstream end face 84 of the projecting portion 80 and the downstream end face 98Y of the large diameter portion 98A are arranged at the same position in the front-rear direction.

Note that both the upstream end and the downstream end of the projecting portion 80 may extend in the axial direction beyond the upstream end and the downstream end of the large diameter portion 98A. Also, only the downstream end of the projecting portion 80 may extend rearward beyond the downstream end of the large-diameter portion 98A. In addition, when the downstream end of the projecting portion 80 extends rearward from the downstream end of the large diameter portion 98A, it is arranged, for example, in the range of the immediately downstream portion 98D.

Moreover, the length along the axial direction of the projecting portion 80 may be the same as the length along the axial direction of the large diameter portion 98A. In the case of this configuration, for example, the upstream end and the downstream end of the projecting portion 80 do not extend in the axial direction beyond the upstream end and the downstream end of the large diameter portion 98A, and the upstream end face 82 of the projecting portion 80 and the downstream end of the projecting portion 80 do not extend in the axial direction. Each of the end faces 84 is arranged along each of the upstream end face 98X and the downstream end face 98Y of the large diameter portion 98A. Furthermore, in the case of this configuration, the protruding portion 80 may be configured such that one of the upstream end and the downstream end extends axially beyond the upstream end and the downstream end of the large diameter portion 98A.

[Replenishment mechanism 39]
The replenishing mechanism 39 is a mechanism for replenishing the toner TN to the stirring path 32C. Specifically, the replenishment mechanism 39 has a toner cartridge 62, a replenishment path 40, a rotating roll 50, a first path 44, and a second path 46, as shown in FIG. .

The toner cartridge 62, as shown in FIG. 1, functions as a container for containing the toner TN. The toner cartridge 62 is formed in a cylindrical shape with both ends in the axial direction closed. As shown in FIG. 3, the toner cartridge 62 is formed with a replenishing port 62A through which the toner TN inside drops and is replenished toward the stirring passage 32C.

The replenishment path 40 is a path for replenishing toner from the toner cartridge 62 toward the stirring path 32C. The replenishment path 40 is formed in the upper wall 32X of the housing 32, as shown in FIG. Specifically, the replenishment path 40 opens at an obliquely upper position on the opposite side of the agitation path 32C to the supply path 32D in the housing 32, and is a replenishment port for the toner cartridge 62 arranged above the housing 32. 62A.

Furthermore, as shown in FIG. 6, the replenishment path 40 is open on the upstream side (front side) of the large diameter portion 98A of the stirring shaft 98. As shown in FIG. Specifically, the replenishment path 40 is open on the upstream side (front side) with respect to the projecting portion 80 . Specifically, the replenishment passage 40 opens at the immediately upstream portion 98B and the upstream portion 98C of the stirring shaft 98 .

Therefore, in the present embodiment, the toner TN is replenished into the housing 32 (specifically, the stirring path 32C) on the upstream side (forward side) of the large diameter portion 98A of the stirring shaft 98 .

As shown in FIG. 3, the rotating roll 50 includes a magnet roll 50A having a circular cross section and a rotating sleeve 50B that covers the outer periphery of the magnet roll 50A and rotates along the outer periphery of the magnet roll 50A. ing. Also, the magnet roll 50A is fixed to the housing 32, and the rotary sleeve 50B rotates around the magnet roll 50A in the arrow B direction by a driving means (not shown).

The magnet roll 50A has a first magnetic pole G1, a second magnetic pole G2, and a third magnetic pole G3 that are installed inside. In this embodiment, for example, the polarity of the first magnetic pole G1 is set to S pole, the polarity of the second magnetic pole G2 is set to N pole, and the magnetic pole of the third magnetic pole G3 is set to S pole. The rotating roll 50 holds the developer G on the outer circumference of the rotating sleeve 50B by the magnetic field formed by the first magnetic pole G1, the second magnetic pole G2 and the third magnetic pole G3.

In the rotary roll 50, the developer G is held in a holding area 51 (see FIG. 6) arranged in the central portion of the rotary sleeve 50B in the axial direction. In the holding area 51 of the rotary sleeve 50B, as shown in FIG. 6, recesses 52 and protrusions 53 are formed on the outer peripheral surface. The concave portions 52 and the convex portions 53 are alternately formed in the circumferential direction of the rotating roll 50 . Further, the concave portions 52 and the convex portions 53 are formed so as to extend along the axial direction of the rotating roll 50 . The first magnetic pole G1, the second magnetic pole G2, and the third magnetic pole G3 of the magnet roll 50A are arranged within the holding area 51. As shown in FIG.

The rotating roll 50 is arranged below the replenishment path 40, as shown in FIG. In a plan view, the size of the opening at the downstream end of the replenishment path 40 is set smaller than the external dimensions of the rotating roll 50, and the rotating roll 50 is arranged at a position that closes the opening.

The lower end of the rotating roll 50 is positioned lower than the upper end of the stirring auger 90 when viewed from the axial direction of the rotating roll 50 and the stirring auger 90 . Furthermore, the right end of the rotating roll 50 is arranged to the right of the left end of the stirring auger 90 . That is, the rotating roll 50 and the stirring auger 90 are arranged so as to overlap each other in both the vertical direction and the horizontal direction.

Further, the rotating roll 50 is arranged along the stirring shaft 98 above the immediately upstream portion 98B of the stirring shaft 98, as shown in FIG. Specifically, the rotating roll 50 is arranged across the immediately upstream portion 98B and the upstream portion 98C of the stirring shaft 98 .

The second blade 92 is arranged in a region 51A from at least the axial center to the downstream end of the holding region 51 of the rotating roll 50 .

In FIG. 6, in order to make it easier to understand the axial positional relationship between the rotating roll 50 and the large diameter portion 98A of the stirring auger 90, the rotating roll 50 is arranged vertically so as not to overlap the stirring auger 90 for convenience. Illustrated.

As shown in FIG. 3, the first passage 44 connects the stirring passage 32C and the replenishment passage 40 upstream of the replenishment passage 40 in the rotation direction B of the rotary roll 50 . The second path 46 connects the stirring path 32C and the replenishment path 40 on the downstream side of the replenishment path 40 in the rotation direction B of the rotary roll 50 . Note that the replenishment path 40 and the first path 44 are examples of passages.

In the rotating roll 50, the rotating sleeve 50B is constantly rotated in the arrow B direction. In the rotary roll 50, the magnetic field formed by the first magnetic pole G1, the second magnetic pole G2, and the third magnetic pole G3 causes the position of the first magnetic pole G1 to move upstream (immediately upstream) of the large-diameter portion 98A of the stirring shaft 98. The developer G staying in the portion 98B and the upstream portion 98C) is retained on the outer circumference of the rotary sleeve 50B. Then, the developer G is conveyed to the third magnetic pole G3 by the rotation of the rotary sleeve 50B, and the holding is released at the position of the third magnetic pole G3.

That is, the rotating roll 50 retains the developer G remaining on the upstream side of the large-diameter portion 98A of the stirring shaft 98, and passes the retained developer G through the first path 44 and the second path 46. . The rotating roll 50 is an example of a holder.

When the amount of developer G in the agitation passage 32C decreases due to the consumption of the developer G and the amount of developer G remaining upstream of the large-diameter portion 98A of the agitation shaft 98 decreases, the replenishment mechanism 39 , the amount of developer G held by the rotating roll 50 decreases, and the second path 46 and the replenishment path 40 are opened. As a result, the toner TN is replenished to the stirring path 32C through the second path 46 and the replenishment path 40 .

On the other hand, when the amount of the developer G in the agitation path 32C increases due to the replenishment of the toner TN, and the amount of the developer G remaining on the upstream side of the large-diameter portion 98A of the agitation shaft 98 increases, the replenishment mechanism 39: The amount of the developer G held by the rotating roll 50 increases, and the developer G blocks the second path 46 and the replenishment path 40 . As a result, replenishment of the toner TN to the agitation path 32C through the second path 46 and the replenishment path 40 is stopped.

(Developing operation of developing device)
Next, the action of the developing device 30 will be described.

Inside the housing 32 of the developing device 30, a rotating supply auger 38 and a rotating stirring auger 90 stir the developer G to circulate between the supply path 32D and the stirring path 32C (see FIG. 3). .

As the developer G is stirred, the toner TN in the developer G rubs against the magnetic carrier, and the toner TN is triboelectrically charged to a predetermined polarity.

As shown in FIG. 3, the developer G is supplied to the developing roll 34 by the rotating supply auger 38, and the developer G supplied to the developing roll 34 is applied to the surface of the developing roll 34 by the magnetic force of the magnet roll 34A. It is held in a state in which a magnetic brush (not shown) is formed on.

Then, the rotating sleeve 34</b>B conveys the developer G to a position facing the photosensitive drum 20 .

The toner TN contained in the developer G conveyed to the development gap of the photoreceptor drum 20 adheres to the electrostatic latent image formed on the photoreceptor drum 20, and the electrostatic latent image is developed as a toner image.

In this manner, the developing device 30 supplies the developer G for forming an image on the paper P to the photosensitive drum 20 .

In the developing device 30, when the amount of the developer G in the agitation passage 32C decreases due to the consumption of the developer G, the amount of the developer G remaining upstream of the large-diameter portion 98A of the agitation shaft 98 decreases. In the mechanism 39, the amount of the developer G held by the rotating roll 50 is reduced, and the second path 46 and the replenishment path 40 are opened. As a result, the toner TN is replenished to the stirring path 32C through the second path 46 and the replenishment path 40 .

On the other hand, when the amount of the developer G in the agitation path 32C increases due to the replenishment of the toner TN, and the amount of the developer G remaining on the upstream side of the large-diameter portion 98A of the agitation shaft 98 increases, the replenishment mechanism 39: The amount of the developer G held by the rotating roll 50 increases, and the developer G blocks the second path 46 and the replenishment path 40 . As a result, the replenishment of toner to the stirring path 32C through the second path 46 and the replenishment path 40 is stopped.

<Action of this embodiment>
Next, the operation according to this embodiment will be described.

In this embodiment, when the stirring shaft 98 is rotated, in the upstream portion 98C of the stirring shaft 98, the blades 93A and 93B of the third blade 93 convey the developer G to the immediately upstream portion 98B. In the immediately upstream portion 98B of the stirring shaft 98, the second blade 92 conveys the developer G toward the large diameter portion 98A.

At this time, part of the developer G is restricted from moving downstream (backward) in the transport direction by the upstream end surface 82 of the projecting portion 80 . Further, the movement of the developer G transported to the upstream end of the large diameter portion 98A in the transport direction is partially restricted by the upstream end surface 98X of the large diameter portion 98A. The developer G that has moved to the large-diameter portion 98A without being restricted by the upstream end surface 98X of the large-diameter portion 98A is conveyed by the first blade 91 to the downstream side (rear side) of the large-diameter portion 98A in the conveying direction.

In this way, the movement of part of the developer G is restricted by the upstream end surface 82 of the overhanging portion 80 and the upstream end surface 98X of the large diameter portion 98A, so that the developer G is transported downstream in the transport direction of the large diameter portion 98A. Fluctuation in the amount of developer G conveyed per rotation of the stirring shaft 98 is suppressed.

Here, in a configuration (first configuration) in which the number of threads and the helical pitches P1 and P2 of the first blade 91 and the second blade 92 are the same as the number of threads and the helical pitch P3 of the third blade 93 (first configuration), for example, the stirring shaft 98 When the number of revolutions increases, or when used in a state where the rear side is arranged downward with respect to the front side, the amount of developer G conveyed to the large diameter portion 98A and the immediately downstream portion 98D is reduced. become more. Therefore, the developer G may be transported downstream of the large-diameter portion 98A in the transport direction without remaining in the immediately upstream portion 98B. That is, the developer G may be transported downstream of the large diameter portion 98A in the transport direction without being restricted by the upstream end surface 82 of the projecting portion 80 and the upstream end surface 98X of the large diameter portion 98A. . As a result, the transport amount of the developer G transported downstream of the large-diameter portion 98A in the transport direction is not stable, and the transport amount of the developer G transported downstream of the large-diameter portion 98A in the transport direction per rotation of the stirring shaft 98 becomes more susceptible to change.

On the other hand, in the present embodiment, as described above, at least one of the first blade 91 and the second blade 92 has at least one of the number of threads and the helical pitch greater than the number of threads and the helical pitch of the third blade 93. made smaller. As a result, compared to the first configuration, the conveying amount per rotation of the stirring shaft 98 in the immediately upstream portion 98B and the large diameter portion 98A of the stirring shaft 98 is small, and the developer G stays in the immediately upstream portion 98B of the stirring shaft 98. Therefore, the bulk of the developer G in the immediately upstream portion 98B is kept high.

For this reason, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the first configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the first configuration, fluctuations in the amount of developer G conveyed per rotation of the stirring shaft 98 that is conveyed downstream of the large-diameter portion 98A in the conveying direction are suppressed. The first configuration does not have the first blade 91 and the second support portion 72, and the third blade 93 is formed so as to reach the immediately upstream portion 98B and the large diameter portion 98A from the upstream portion 98C. can be grasped.

More specifically, in this embodiment, both the first blade 91 and the second blade 92 have at least one of the number of threads and the spiral pitch smaller than the number of threads and the spiral pitch of the third blade 93 . As a result, in only one of the first blade 91 and the second blade 92, at least one of the number of threads and the spiral pitch is smaller than the number of threads and the spiral pitch of the third blade 93 (second configuration). Since the conveying amount per rotation of the stirring shaft 98 in the immediately upstream portion 98B and the large diameter portion 98A of the shaft 98 is small, the developer G tends to stay in the immediately upstream portion 98B of the stirring shaft 98. The bulky state of the developer G is maintained.

For this reason, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the second configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the second configuration, variation in the amount of developer G conveyed per rotation of the stirring shaft 98 that is conveyed downstream in the conveying direction of the large-diameter portion 98A is suppressed.

More specifically, in this embodiment, both the first blade 91 and the second blade 92 are smaller in both the number of threads and the spiral pitch than the number of threads and the spiral pitch of the third blade 93 . That is, the number of rows of the first blade 91 and the second blade 92 is less than the number of rows of the third blade 93, and the spiral pitch P1 of the first blade 91 and the spiral pitch P2 of the second blade 92 are equal to the third blade 93 is made smaller than the spiral pitch P3 of the blades 93A and 93B. As a result, in both the first blade 91 and the second blade 92, only one of the number of threads and the helical pitch is smaller than the number of threads and the helical pitch of the third blade 93 (third configuration). Since the conveying amount per one rotation of the stirring shaft 98 at the immediately upstream portion 98B and the large diameter portion 98A of 98 is small and the developer G tends to stay in the immediately upstream portion 98B of the stirring shaft 98, development at the immediately upstream portion 98B The bulky state of the agent G is maintained.

For this reason, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the third configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the third configuration, fluctuations in the amount of the developer G transported downstream in the transport direction of the large diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Further, in this embodiment, the outer diameter D2 of the second blade 92 is smaller than the outer diameter D1 of the first blade 91 . Therefore, compared to the configuration (fourth configuration) in which the outer diameter D2 of the second blade 92 is the same as the outer diameter D1 of the first blade 91, the second blade 92 is radially outward from the large diameter portion 98A. Since the area of the overhanging portion is reduced, the force for pushing the developer G toward the downstream side of the large-diameter portion 98A in the transport direction is reduced. Therefore, compared to the fourth configuration, the developer G is likely to stay in the immediately upstream portion 98B, and the bulk of the developer G in the immediately upstream portion 98B is effectively maintained.

As a result, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the fourth configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the fourth configuration, fluctuations in the amount of developer G transported downstream in the transport direction of the large-diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Further, in the present embodiment, the thickness T2 of the second blade 92 along the axial direction of the stirring shaft 98 is greater than the thickness T1 of the first blade 91 along the axial direction. As a result, the thickness T2 of the second blade 92 along the axial direction of the stirring shaft 98 is the same as the thickness T1 of the first blade 91 along the axial direction (fifth configuration). The second blade 92 fills the outer peripheral space of the immediately upstream portion 98B of the blade 98 . Therefore, the volume of the outer peripheral space of the immediately upstream portion 98B of the stirring shaft 98 is smaller than in the fifth configuration, and the bulk of the developer G in the immediately upstream portion 98B is kept high.

As a result, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the fifth configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the fifth configuration, fluctuations in the amount of developer G transported downstream in the transport direction of the large diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

In addition, in the present embodiment, the length of the space between the blades of the second blade 92 along the axial direction of the stirring shaft 98 is longer than the length of the space between the blades of the first blade 91 along the axial direction. shortened. As a result, the second blade 92 has a configuration in which the length of the space between the blades along the axial direction of the stirring shaft 98 is the same as the length of the space between the blades along the axial direction of the first blade 91 (the sixth configuration), the volume of the outer peripheral space of the immediately upstream portion 98B of the stirring shaft 98 becomes smaller, and the bulk of the developer G in the immediately upstream portion 98B is maintained.

As a result, for example, even when the number of rotations of the stirring shaft 98 is increased, or when the rear side is used in an inclined state so that the front side is disposed downward, the developer G is more likely to be dissipated than in the sixth configuration. , while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the sixth configuration, fluctuations in the amount of developer G transported downstream in the transport direction of the large-diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Moreover, in this embodiment, the first blade 91 is formed so as to reach the outer peripheral surface of the immediately downstream portion 98</b>D of the stirring shaft 98 . As a result, compared to the configuration (seventh configuration) in which the first blade 91 is formed only in the large diameter portion 98A and the fourth blade 94 is formed in the portion 98D directly downstream of the stirring shaft 98, the developer G Easy to stay in 98D. As a result, compared to the seventh configuration, the developer G tends to stay in the immediately upstream portion 98B of the stirring shaft 98, and the bulk of the developer G in the immediately upstream portion 98B is maintained.

As a result, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the seventh configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the seventh configuration, fluctuations in the amount of developer G transported downstream in the transport direction of the large diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Further, in the present embodiment, the first blade 91 reaches the downstream side (rear side) of the downstream end (the downstream end face 84 described later) of the projecting portion 80 . Therefore, the first blade 91 is arranged on the upstream side (forward side) of the downstream end (downstream end face 84) of the overhanging portion 80, and is positioned downstream from the downstream end (downstream end face 84) of the overhanging portion 80 to the fourth blade. The developer G tends to stay downstream of the projecting portion 80 compared to the configuration (eighth configuration) in which the blades 94 are formed. As a result, compared to the eighth configuration, the developer G tends to stay in the immediately upstream portion 98B of the stirring shaft 98, and the bulk of the developer G in the immediately upstream portion 98B is maintained.

As a result, for example, even when the rotational speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the eighth configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the eighth configuration, fluctuations in the amount of developer G transported downstream in the transport direction of the large diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Further, in the present embodiment, as shown in FIG. 6, the axial length of the projecting portion 80 is greater than or equal to the axial length of the large-diameter portion 98A. For this reason, compared to the configuration (ninth configuration) in which the length of the protruding portion 80 along the axial direction is less than the length of the large diameter portion 98A along the axial direction (the ninth configuration), stirring in and around the large diameter portion 98A The road width of the road 32C is narrowed. As a result, compared to the ninth configuration, the developer G is more likely to stay in the immediately upstream portion 98B of the stirring shaft 98, and the bulk of the developer G in the immediately upstream portion 98B is maintained.

As a result, for example, when the rotational speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the ninth configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the ninth configuration, fluctuations in the amount of the developer G transported downstream in the transport direction of the large-diameter portion 98A per rotation of the stirring shaft 98 are suppressed.

Further, in the present embodiment, as shown in FIG. 6, the upstream end of the projecting portion 80 axially extends further than the upstream end of the large diameter portion 98A. For this reason, compared to the configuration (tenth configuration) in which the projecting portion 80 is arranged in the range from the upstream end to the downstream end of the large diameter portion 98A, the passage width of the large diameter portion 98A and the agitation passage 32C around it is reduced to narrow. As a result, compared to the tenth configuration, the developer G tends to stay in the immediately upstream portion 98B of the stirring shaft 98, and the bulk of the developer G in the immediately upstream portion 98B is maintained.

As a result, for example, when the rotation speed of the stirring shaft 98 is increased, or when the developer G is used in a state in which the rear side is arranged downward with respect to the front side, compared to the tenth configuration, the developer G However, while being restricted by the upstream end face 82 of the projecting portion 80 and the upstream end face 98X of the large diameter portion 98A, the state of being conveyed downstream in the conveying direction of the large diameter portion 98A is maintained. As a result, compared to the tenth configuration, fluctuations in the amount of the developer G transported downstream in the transport direction of the large-diameter portion 98</b>A per one rotation of the stirring shaft 98 are suppressed.

Moreover, in this embodiment, the first blade 91 is formed continuously with the second blade 92 . Therefore, compared to the configuration (eleventh configuration) in which the first blade 91 and the second blade 92 are separated, the developer G is easily transported from the immediately upstream portion 98B of the stirring shaft 98 to the large diameter portion 98A. . Therefore, compared to the eleventh configuration, it is easier to adjust the retention amount of the developer G so as to reduce the retention amount in the immediately upstream portion 98B. That is, it can be used as an adjustment factor (adjustment margin) for adjusting the amount of developer G retained in the immediately upstream portion 98B.

Further, in this embodiment, as shown in FIG. 6 , the rotating roll 50 is arranged along the stirring shaft 98 above the immediately upstream portion 98B of the stirring shaft 98 . Here, in the configuration (the twelfth configuration) in which the rotating roll 50 is arranged above only the upstream portion 98C, the developer G present in the upstream portion 98C is held where the developer G is less likely to stay than in the immediately upstream portion 98B. Therefore, the holding amount of the developer G held by the rotating roll 50 is not stable in the axial direction, and the holding amount may vary in the axial direction.

In contrast, in the present embodiment, the rotating roll 50 is arranged along the stirring shaft 98 on the upper side of the immediately upstream portion 98B of the stirring shaft 98. Therefore, compared to the twelfth configuration, the developing state is bulky. Agent G is held on rotating rolls 50 . Therefore, compared to the twelfth configuration, variation in the amount of developer G held by the rotating roll 50 in the axial direction is suppressed.

Further, in this embodiment, the second blade 92 is arranged in the region 51A from at least the axial center to the downstream end in the holding region 51 of the rotating roll 50 . Therefore, compared to the configuration (thirteenth configuration) in which the second blade 92 is arranged in the region on the downstream side of the holding region 51 of the rotating roll 50 in the axial direction, the bulky developer G rotates. It is held on the roll 50 . Therefore, compared to the thirteenth configuration, variation in the amount of developer G retained by the rotating roll 50 in the axial direction is suppressed.

In this way, variation in the amount of the developer G held by the rotating roll 50 in the axial direction is suppressed, so that the developer G stays in the first path 44, the second path 46, and the replenishment path 40. Variation in the axial direction of the quantity is suppressed. As a result, the first path 44, the second path 46, and the replenishment path 40 are blocked with the developer G from one end to the other end in the axial direction, and the replenishment of the toner TN is appropriately stopped.

As described above, in the present embodiment, variation in the amount of developer G transported per rotation of the stirring shaft 98 in the developer G transported downstream in the transport direction of the large-diameter portion 98A is suppressed. fluctuation is suppressed. As a result, development defects are suppressed, and image defects caused by the development defects are suppressed.

(Modification)
In this embodiment, both the number of threads and the spiral pitches P1 and P2 of both the first blade 91 and the second blade 92 are smaller than the number of threads and the spiral pitch P3 of the third blade 93. is not limited to For example, both the first blade 91 and the second blade 92 may have at least one of the number of threads and the spiral pitches P1 and P2 smaller than the number of threads and the spiral pitch P3 of the third blade 93 . Any one or more of the four values of the helical pitch P1 of the first blade 91, the helical pitch P2 of the second blade 92, the number of threads of the first blade 91, and the number of threads of the second blade 92 It should be smaller than the value of the three blades 93 .

Also, in the present embodiment, the outer diameter D2 of the second blade 92 is smaller than the outer diameter D1 of the first blade 91, but this is not the only option. For example, the outer diameter D2 of the second blade 92 may be the same as the outer diameter D1 of the first blade 91 .

In the present embodiment, the thickness T2 of the second blade 92 along the axial direction of the stirring shaft 98 is greater than the thickness T1 of the first blade 91 along the axial direction. can't For example, the second blade 92 may have a thickness T2 along the axial direction of the stirring shaft 98 that is the same as the thickness T1 of the first blade 91 along the axial direction.

In addition, in the present embodiment, the length of the space between the blades of the second blade 92 along the axial direction of the stirring shaft 98 is longer than the length of the space between the blades of the first blade 91 along the axial direction. Although it was shortened, it is not limited to this. For example, the second blades 92 may have a configuration in which the length of the space between the blades along the axial direction of the stirring shaft 98 is the same as the length of the space between the blades along the axial direction of the first blade 91. good.

Moreover, in the present embodiment, the first blade 91 is formed so as to reach the outer peripheral surface of the immediately downstream portion 98D of the stirring shaft 98, but it is not limited to this. For example, the configuration may be such that the first blade 91 is formed only on the large diameter portion 98A. In this case, for example, the fourth vane 94 is formed on the immediately downstream portion 98D of the stirring shaft 98 .

Further, in the present embodiment, the first blade 91 reaches the downstream side (rear side) of the downstream end (downstream end surface 84) of the overhanging portion 80, but this is not the only option. For example, the first blade 91 is arranged on the upstream side (forward side) from the downstream end (downstream end surface 84) of the overhanging portion 80, and the fourth blade 91 is arranged downstream from the downstream end (downstream end surface 84) of the overhanging portion 80. 94 may be formed.

In the present embodiment, as shown in FIG. 6, the axial length of the projecting portion 80 is greater than or equal to the axial length of the large-diameter portion 98A. Not limited. For example, the length along the axial direction of the projecting portion 80 may be less than the length along the axial direction of the large diameter portion 98A.

Further, in the present embodiment, as shown in FIG. 6, the upstream end of the protruding portion 80 axially extends further than the upstream end of the large diameter portion 98A, but this is not the only option. For example, the overhanging portion 80 may be arranged in a range from the upstream end to the downstream end of the large diameter portion 98A.

Moreover, although the first blade 91 is formed continuously with the second blade 92 in the present embodiment, it is not limited to this. For example, the first blade 91 and the second blade 92 may be separated.

Further, in the present embodiment, as shown in FIG. 6, the rotating roll 50 is arranged along the stirring shaft 98 above the immediately upstream portion 98B of the stirring shaft 98, but this is not the only option. For example, the configuration may be such that the rotating roll 50 is arranged above only the upstream portion 98C.

In addition, in the present embodiment, the second blade 92 is arranged in the region 51A from at least the axial center to the downstream end in the holding region 51 of the rotating roll 50, but it is not limited to this. For example, the second blade 92 may be arranged in a region on the downstream end side of the axial center of the holding region 51 of the rotating roll 50 .

In this embodiment, the toner TN and the developer G are used as the powder, but the powder is not limited to this. The powder may be powdery.

The present invention is not limited to the above-described embodiments, and various modifications, changes, and improvements are possible without departing from the scope of the invention. For example, the modifications shown above may be configured by combining a plurality of them as appropriate.

10 Image forming apparatus 20 Photoreceptor drum (an example of a latent image carrier)
22 transfer roll (an example of the transfer section)
30 developing device 31 conveying mechanism 32 housing 34 developing roll (an example of a supplier)
50 rotating roll (an example of a holder)
51 holding area 51A area 80 projecting portion 91 first blade 92 second blade 93 third blade 98 stirring shaft (an example of a shaft portion)
98A large diameter portion 98B immediately upstream portion 98C upstream portion 98D immediately downstream portion G developer (an example of powder)
TN toner (an example of powder)
P paper (an example of a recording medium)

Claims (16)

a housing containing powder;
a shaft portion disposed inside the housing and having a large-diameter portion with a large diameter partly in the axial direction;
a protruding portion formed on the inner wall of the housing and protruding from the radially outer side of the large diameter portion toward the large diameter portion;
a first blade spirally formed on the outer peripheral surface of the large-diameter portion for conveying the powder in one direction in the axial direction by rotation of the shaft portion;
a second blade spirally formed on the outer peripheral surface of the portion of the shaft portion immediately upstream of the large-diameter portion for conveying the powder to the one side by rotation of the shaft portion;
a third blade spirally formed on the outer peripheral surface of the upstream portion of the shaft portion with respect to the immediately upstream portion for conveying the powder to the one side by rotation of the shaft portion;
with
At least one of the first blade and the second blade has a number of threads and a spiral pitch that are smaller than those of the third blade. 2. The conveying mechanism according to claim 1, wherein both the first blade and the second blade have at least one of the number of threads and the spiral pitch smaller than the number of threads and the spiral pitch of the third blade. 3. The conveying mechanism according to claim 2, wherein the number of threads and the helical pitch of both the first blade and the second blade are smaller than the number of threads and the helical pitch of the third blade. The conveying mechanism according to any one of claims 1 to 3, wherein the second blade has an outer diameter smaller than the outer diameter of the first blade. The conveying mechanism according to any one of claims 1 to 4, wherein the thickness of the second blade along the axial direction is greater than the thickness of the first blade along the axial direction. 5. Any one of claims 1 to 4, wherein the second blade has a space between the blades along the axial direction shorter than a space between the blades of the first blade along the axial direction. A transport mechanism according to the above paragraph. The conveying mechanism according to any one of claims 1 to 6, wherein the first blade is formed continuously with the second blade. The conveying mechanism according to any one of claims 1 to 7, wherein the first blade is formed so as to reach the outer peripheral surface of the portion of the shaft portion immediately downstream of the large diameter portion. The conveying mechanism according to claim 8, wherein the first blade reaches the downstream side of the downstream end of the projecting portion. The conveying mechanism according to any one of claims 1 to 9, wherein the axial length of the projecting portion is greater than or equal to the axial length of the large diameter portion. 11. The conveying mechanism according to claim 10, wherein at least one of the upstream end and the downstream end of the projecting portion extends further in the axial direction than at least one of the upstream end and the downstream end of the large diameter portion. 12. The conveying mechanism according to any one of claims 1 to 11, further comprising: a holding body arranged along the shaft above the immediately upstream portion and holding the powder stagnating in the immediately upstream portion on an outer periphery thereof. . The second blade is
13. The conveying mechanism according to claim 12, wherein the holding body is arranged at least in an area from the center in the axial direction to the downstream end in the holding area for holding the powder. The transport mechanism according to any one of claims 1 to 13, wherein the toner as the powder is replenished into the housing on the upstream side with respect to the large diameter portion, and the developer containing the toner is transported;
a supply body for supplying the developer conveyed by the conveying mechanism to the latent image;
Developing device. 14. The transport mechanism according to claim 12 or 13, wherein the transport mechanism is replenished with the toner through a passage,
15. The developing device according to claim 14, wherein the holding member conveys the held developer to the passage, blocks the passage with the developer, and stops the replenishment of the toner. a latent image holder that holds a latent image;
16. The developing device according to claim 14 or 15 for developing the latent image;
a transfer unit that transfers the image developed by the developing device to a recording medium;
An image forming apparatus comprising:

Images