JP4790352B2 - Rotary developer - Google Patents

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a complex machine using an electrophotographic process, and more particularly to a so-called rotary type developing device.

  In general, in a color image forming apparatus, a developer for each color is supported on a cylindrical rotary rack configured to be rotatable by using a one-component developer, and a developing roller of each color developer is a photosensitive drum or the like. In some cases, a so-called rotary type developing device that sequentially develops the image bearing member is used, and each color developing device includes a developing chamber in which a developing roller is disposed, a developer accommodating chamber in which a developer is accommodated, and a developer accommodating chamber. Is provided.

  In such a rotary type developing device, when the rotary type rack rotates, the vertical relationship between the developing chamber and the developer containing chamber changes, causing an excessive developer supply, and fogging may occur. A developer having a large particle size in the developing chamber may be returned to the developer containing chamber or the developer cartridge. Even if the developing chamber and the developer cartridge are separated from each other, only the developer having a small particle size is used for development first, and the developer having a large particle size remains, so that the image quality of the formed image is gradually deteriorated. May end up.

  In addition, when new developer enters the developer chamber from the developer storage chamber or developer cartridge during development, the powder pressure changes greatly, and the already charged developer and new developer are mixed, resulting in poor charging and image quality degradation. Sometimes. Even when the developing device is rotated, there is a developer that is partially retained and cannot be used or discharged. When the developer cartridge is empty and replaced with a developer cartridge containing new developer. A new developer and a deteriorated developer may be mixed to cause a charging failure, resulting in a decrease in image quality.

  In order to prevent such problems, a regulated space is formed by a housing, a supply roller, a developing roller, and a regulating member that is in contact with the supply roller. When the deteriorated developer can pass through the regulating member by gravity due to the rotation of the rotary so that the developer does not enter from the developer reservoir, the developer is returned to the developer reservoir and mixed with the new developer. In some chambers, excessive accumulation of deteriorated developer and its harmful effects are suppressed (see Patent Document 1).

JP 2002-189346 A

  However, in the rotary type developing device described in Patent Document 1, the regulated space is formed by the housing, the supply roller, the development roller, and the regulation member in contact with the supply roller, but the powder pressure is kept constant in the development chamber. If the powder pressure is not constant, the developer charge amount and the transport amount on the developing roller will fluctuate greatly.

  Further, in Patent Document 1, although the gap between the developer supply roller and the development housing is reduced and the inflow of new developer is prevented by a developer inflow prevention valve or the like, the ability to discharge deteriorated developer is poor, and many When printing on a sheet, the developer powder pressure in the restricting portion may increase, which may cause adverse effects such as developer leakage. Further, in Patent Document 1, there is a problem that the developing device and the developer storage portion (developer storage chamber) cannot be divided, and the developer cartridge must be replaced when the developer cartridge is replaced. is there.

  In order to solve the above-described problems, an object of the present invention is to provide a developing device that can keep the powder pressure constant and can replace only the developer cartridge.

In order to solve the above-described problems, the present invention provides a rotatable rotary rack that includes a plurality of development chambers and a developer storage chamber that is disposed adjacent to and corresponding to the development chambers and that stores a developer. A rotary roller provided in the developing chamber for developing an electrostatic latent image formed on the image bearing member; and a supply roller arranged in the developing chamber for supplying a developer to the developing roller. In the rotary type developing apparatus in which the developing roller is positioned at a developing position that sequentially faces the image carrier by the rotation of the developer container , the developer storage chamber is detachable from the rotary type rack, and is mounted on the rotary type rack. In this state, the rotation of the rotary rack extends from the track drawn by the developing roller toward the center of the rotary rack from the supply roller. Partition between the developing chamber by, and by said rotary rack and the partition wall, and the developing chamber wherein by rotation of the rotary rack than trajectory developing roller draws the center side of the rotary rack A partition wall provided so as to have an opening communicating with the developer accommodating chamber, wherein the developing chamber is located above the corresponding developer accommodating chamber at the developing position, and defines the opening; A holding wall is formed on one end side of the partition wall so as to extend above the extending direction of the partition wall at the developing position.

  As described above, the present invention includes a partition wall that partitions the developing chamber and the developer storage chamber, and the partition wall and the rotary rack have a rotary type rather than the track drawn by the developing roller by the rotation of the rotary rack. An opening communicating with the developing chamber and the developer accommodating chamber is defined on the center side of the rack, and the developing chamber is positioned above the corresponding developer accommodating chamber at the developing position, and one end of the partition wall defining the opening. Since a holding wall extending above the extending direction of the partition wall at the developing position is formed on the side, the toner in the developing chamber is regulated by the holding wall, so that the toner reliably remains on the partition wall. Therefore, the toner can be reliably stored in the developing chamber regardless of the fluidity of the toner, and the powder pressure of the developer can be kept constant, as well as the developer cartridge. There is an effect that it is possible to carry out the exchange of only.

  In the present invention, since the partition wall extends toward the center of the rotary rack, the sliding-off of the toner from the rear end (center side end) of the partition wall is suppressed, and the toner is reliably transferred to the developing chamber. In addition to being able to store, there is an effect that the developer in the developer storage chamber and the developer in the development chamber can be reliably mixed.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

Referring to FIG. 1, an illustrated image forming apparatus includes a laser scanning unit (exposure device) 1, a photosensitive drum (image carrier) 2, a charging device 3, a rotary developing device 4, a cleaning rubbing member 5, The apparatus includes a cleaning device 6, an intermediate transfer unit 7, a fixing device 8, a paper feed cassette 9, a secondary transfer roller 10, and a discharge unit (discharge tray) 11. The intermediate transfer unit 7 includes intermediate transfer belts 71 and 1. The intermediate transfer belt 71 including the next transfer roller 72 is cleaned by the cleaning device 12. The rotary developing device 4 includes a developing chamber 41 (developing housing) indicated by black (BK) 41 ₁ , magenta (M) 41 ₂ , cyan (C) 41 ₃ , and yellow (Y) 41 ₄ , and developing chambers of the developing chamber 41. black provided corresponding to (BK) 42 _1, magenta (M) 42 _2, cyan (C) 42 _3, yellow (Y) 42 ₄ of the developer (toner) containing chamber have a (developer cartridge) 42 is doing.

At the time of image formation, the photosensitive drum 2 is uniformly charged by the charging device 3, and the photosensitive drum 2 is exposed by the exposure device according to the image data, and an electrostatic latent image is formed on the photosensitive drum 2. It is formed. Then, the rotary developing device 4 is rotationally driven by a driving unit (not shown), and the developing roller 47 disposed in the developing chambers 41 _{1 to} 41 ₄ is sequentially set to a developing position facing the photosensitive drum 2. Then, the electrostatic latent image on the photosensitive drum 2 is developed. Each color toner image on the photosensitive drum 2 is transferred to the intermediate transfer belt 71 by the primary transfer roller 72, and a color toner image is formed on the intermediate transfer belt 71. The color toner image on the intermediate transfer belt 71 is transferred to the recording paper conveyed from the paper feed cassette 9 by the secondary transfer roller 10 at the secondary transfer position. Thereafter, the recording paper is sent to the fixing device 8, where the color toner image is fixed on the recording paper and discharged onto the paper discharge tray 11.

2 and 3, the rotary type developing device 4 includes a cylindrical rotary type rack 40, and the space formed between the front and rear side walls 40 a and 40 b having a substantially disk shape and the front and rear side walls is divided into four. A partition wall 40c having a cross-shaped cross section for equally dividing the space for color development is provided. The four developing chambers of black (BK) 41 ₁ , magenta (M) 41 ₂ , cyan (C) 41 ₃ , and yellow (Y) 41 ₄ described above are arranged in each space thus partitioned.

  Referring to FIG. 4, a developing chamber (developing housing) 41 is disposed on the upper side of the space defined by the partition wall 40 c, and a developer storage chamber (developing) that can be replaced below the developing chamber 41. Agent cartridge) 42 is positioned. The developer accommodating chamber 42 has an outer shape shown in FIG. 2, and includes a substantially fan-shaped front and rear side wall portion 42a, a curved surface portion 42b along the circumference of the front and rear side walls 40a and 40b of the rotary rack, and a rotary. The side wall 42c is in contact with the partition wall 40c of the mold rack and the remaining side wall 42d, and a developer (single component developer) 45 is accommodated therein.

  A substantially convex fan-shaped side wall portion 42 a of the developer accommodating chamber is provided with a guide convex portion 421 for fixing the developer accommodating chamber (developer cartridge) 42 to the cylindrical rotary rack 40.

  Next, referring to FIG. 5, a part of the side wall 42d is formed with a shutter 43 (not shown in FIG. 4) that opens and closes in conjunction with attachment to and removal from the cylindrical rotary rack 40. The developer accommodating chamber 42 is configured to be openable and closable around a rotation shaft 422 positioned at a ridge 42e where two side walls 42c and 42d are in contact. The shutter 43 may incorporate a spring (not shown) that closes the shutter 43 when the developer accommodating chamber (developer cartridge) 42 is removed from the cylindrical rotary rack 40.

  The shutter 43 is opened and closed by an opening / closing protrusion 431, a guide groove 401 is provided in the cylindrical rotary rack 40, and the guide convex portion 421 of the developer storage chamber 42 is inserted. A shutter opening / closing groove 402 is provided in the cylindrical rotary rack 40 and guides an opening / closing protrusion 431 provided in the shutter 43. Although not shown in the drawing, a guide convex portion 421 is also formed on the rear side wall portion 42a, and an opening / closing projection 431 is formed on the rear side of the shutter 43, and a guide groove 401 and a shutter opening / closing portion are also formed on the inner side of the front side wall 40a. A groove 402 is formed.

  Returning to FIG. 4 again, the configuration of the developing chamber 41 will be described. A developing roller 47 is positioned in the developing chamber 41 so as to face the photosensitive drum 2. As described above, the electrostatic latent image formed on the surface of the photosensitive drum 2 is held on the surface of the developing roller 47. Develop with the one-component developer. A supply roller 46 is positioned on the opposite side of the photosensitive drum 2 with respect to the developing roller 47. The supply roller 46 and the developing roller 47 may or may not be in contact with each other. However, in this embodiment, the supply roller 46 is in contact with the developing roller 47 while being in contact with the developing roller 47 in the counter direction. Rotate.

  Between the developing roller 47 and the partition wall 40c of the rotary rack 40 adjacent to the roller 47, a regulating blade 48 for regulating the developer layer thickness on the developing roller 47 and charging the developer is provided. . In the illustrated example, it is directly attached to the partition wall 40 c of the rotary rack 40. The regulation blade 48 may be provided with a thin metal plate-like member such as stainless steel or phosphor bronze, or an elastic member such as rubber or a resin member at the tip of the metal plate-like member.

  The regulating blade 48 is fixed to the wall of the developing chamber 41 in a so-called counter state so that the leading end (free end) of the regulating blade is positioned upstream of the fixed end in the rotation direction of the developing roller 47. Although the tip of the regulation blade 48 is not bent, the tip may be bent to adjust the toner conveyance amount, and the tip shape is not particularly defined. The regulating blade 48 is in elastic contact with the surface at the contact position with the developing roller 47. Therefore, depending on the contact state of the regulating blade 48, more specifically, the toner formed on the surface of the developing roller 47 by the protruding amount from the contact portion to the tip, the regulating pressure, the tip shape, the free length of the regulating blade 48, etc. The thickness of the layer is finally determined, and the toner on the developing roller 47 is charged to a predetermined polarity by rubbing against the regulating blade 48 at this contact position.

  In FIG. 4, a side wall 41 a is provided below the developing roller 47 so as to be attached to the front and rear side walls 40 a and 40 b of the rotary rack 40 so that the developer 44 does not spill from the developing chamber 41. A surface parallel to the tangential direction with respect to the roller surface of the developing roller 47 is formed at the end of the developing chamber side wall 41a, and the developer does not leak to the outside from between the developing roller 47 and the developing chamber side wall 41a. In addition, a static elimination seal 49 for eliminating static electricity is provided.

  In the state where the developing roller 47 as shown in FIG. 4 is positioned so as to be developable with respect to the photosensitive drum 2, the side wall 42d of the developer accommodating chamber 42 is directed toward the rotation center of the rotary rack. The developer reservoir 44 can be formed in cooperation with the adjacent developing chamber side wall 41a, and a part of the supply roller 46 described above is in this state. A portion thereof is positioned at 44.

  Thus, the developer in the developer reservoir 44 is supplied to the developing roller 47 as the supply roller 46 rotates, and the developer on the developing roller 47 is in the state of a predetermined amount of toner thin layer by the regulating blade 48. It can be carried to the electrostatic latent image formed on it. In the following description, the present invention will be described using a non-magnetic developer as an example, but the present invention can also be applied to a developing device using a magnetic developer.

  Such a rotary type developing device 4 has a rotary type developing device as shown in FIG. 4 in which the structure of one color developing chamber 41 facing the photosensitive drum 2 and the replaceable developer containing chamber 42 is shown. When the developing chamber 41 is fixed to the cylindrical rack 40 in FIG. 4 and the developing roller 47 provided in the developing chamber 41 faces the photosensitive drum 2, it is adjacent to the developing chamber 41 and is on the lower side. The developer accommodating chamber 42 is detachably supported by a cylindrical rotary rack 40 or each developing chamber 41 by a positioning member and a coupling member (not shown).

  As will be described later, the developer containing chamber 42 for each color is replaced from the position where the developing roller 47 of the developing chamber 41 faces the photosensitive drum 2 from the position where the developing roller 47 of the developing chamber 41 for the next color is the photosensitive drum 2. When the developing roller 47 in the developing chamber 41 is on the upper side and the developer containing chamber 42 is also on the upper side, the upper cover of the image forming apparatus can be opened to perform the above operation. In addition, a coupling member (not shown) is fixed by a stopper member linked to the rotary rotation position so as to be detachable only at this position.

  When the developer storage chamber 42 is removed from the cylindrical rotary rack 40, the shutter 43 is closed by a spring force (not shown) as shown in FIG. There is no spillage of the developer. Then, the guide convex portion 421 in the developer storage chamber (developer cartridge) 42 is put into a guide groove 401 provided in the front and rear side walls 40a and 40b of the cylindrical rotary rack 40 shown in FIG. When the opening / closing protrusion 431 of the shutter 43 is inserted into the shutter opening / closing groove 402 of the cylindrical rotary rack 40 and inserted into the cylindrical rotary rack 40, the shutter opening / closing groove 402 is bent halfway, so that the shutter 43 is shown in FIG. 5 opens and communicates with the developing chamber 41 in the central direction of the cylindrical rotary rack 40, so that the developer inside can freely move between the developing chamber 41 and the developer containing chamber 42. You can come and go.

In the rotary developing device 4 described above, when there is a sufficient amount of developer stored, the developer moves as shown in FIG. First, in the developing position where the developing roller 47 ₁ is facing the photosensitive drum 2, as shown, the partition walls 40c cross section cross-shaped rotary rack 40, the partition wall 40c is horizontal or vertical direction As shown in FIG. 4, the side wall 42d of the developer storage chamber 42 has an inclined surface that rises toward the rotation center of the rotary rack, as shown in FIG. The developer reservoir 44 can be formed in cooperation with the side wall 41a.

As a result, in the developing position, leaving only the developer 44 ₁ stored in the 42d side walls of the developer accommodating chamber 42, mostly, are stored in the positioned under developing chamber developer accommodating chamber 42 ₁ Yes. Thus, the developer 44 ₁ in the developing chamber 41 ₁ is the optimum amount to the developer, other developers have been stored in such a state that the developer accommodating chamber 42 ₁ to 45 _1.

Then, due to the rotation of the cylindrical rotary rack 40 immediately after the end of the development in the counterclockwise direction in the drawing, the developing roller 47 ₁ in the developing chamber 41 ₁ comes to the upper position and the developing chamber comes to the position indicated by _{4 14} in FIG. When the developer 44 ₁ in the developing chamber shown in ₄₁₁ is dropped toward the center of the cylindrical rotary rack 40 is at the position of the 41 _4, also developer chamber (developer cartridge) 42 in the _first developer Similarly, they gather in the central direction of the cylindrical rotary rack 40.

Then, when the cylindrical rotary rack 40 is further rotated to the positions indicated by 41 ₃ and 42 ₃ in FIG. 3, the developer in the developing chamber 41 ₁ in the middle is new to the developer containing chamber 42 ₁ . now while mix with the developer flows into the developing chamber 41 _3, further when by rotating the cylindrical rotary rack 40 becomes the position shown in FIG. 3 to 41 _2, 42 _2, of the developer to the developing chamber 41 ₂ The flow stops.

When the further rotation of the cylindrical rotary rack 40, the developer that has been in the developing chamber 41 ₂ on the way to the development position shown in 41 _1, 42 ₁ in Figure 3, leaving the optimum amount developing developing spills containing chamber (developer cartridge) 42 ₁ side, when it reaches the development position, the developer 44 ₁ in the developing chamber 41 ₁ is the optimum amount to the developer.

  This is exactly the same when the amount of developer in the developer accommodating chamber 42 is reduced, and the developer accommodating chamber 42 and the developing chamber 41 communicate with each other in the central direction of the cylindrical rotary rack 40. The developer is always filled in the developing chamber 41 by the rotation of the cylindrical rotary rack 40, and then unnecessary developer is spilled into the developer containing chamber (developer cartridge) 42. Only the developer remains.

FIG. 6 shows the movement of the developer and the position where the developer storage chamber (developer cartridge) 42 is replaced when the amount of the developer in the developer storage chamber 42 decreases. That is, in FIG. 6, but the developing roller 47 ₁ is at the development position that faces the photosensitive drum 2, the developer 44 ₁ in the developing chamber 41 ₁ is in the optimum amount to the developer, the developer accommodating chamber 42 ₁ of the developer is very small as 45 _1.

Then, drawing counterclockwise cylindrical rotary rack 40 is rotated as described above, when the developing chamber 41 ₁ comes to the position shown in 41 _4, the developer 44 ₁ in the developing chamber 41 ₁ of the 41 ₄ in the position falls in the center of the cylindrical rotary rack 40, a small mountain 45 ₄ shown in the center direction of the cylindrical rotary rack 40 by the dotted line together with the developer accommodating chamber 42 ₁ in the developer.

Further rotating the cylindrical rotary rack 40 rotates, at a position indicated by reference numeral 41 _3, 42 ₃ 6, the developer 45 ₄ as it flows into the developing chamber 41 _3, further a cylindrical rotary rack 40 If _is, 41 2, 42 positions from ₄₁ 1 shown in _2, 42 on the way to the development position indicated by _1, the developer that has been in the developing chamber 41 _2, developer, leaving only the optimum amount to the developer spill chamber 42 ₁ side, when it reaches the development position, the developer 44 ₁ in the developing chamber 41 ₁ is in the optimum amount for development.

When the exchange is less developer in the developer accommodating chamber 42 is required, as shown in FIG. 6, when trying to retrieve the developer chamber from the cylindrical rotary rack 40 at the position of 42 _4, 2 the shutter opening and closing grooves 402 shown closing projection 431 of the shutter 43 is moved in the direction of closing between the shutter 43 to reach the bent portions, the mountain of the developer the developer accommodating chamber 42 ₄ shown in 45 ₄ 6 to captured, it is possible to replace the developer accommodating chamber 42 ₄ without causing the developer spills.

  By the way, in this rotary type developing device 4, as shown in FIG. 4, the rear end (that is, the radial center side end) of the side wall (partition wall) 42d is extended upward from the extending direction of the partition wall 42d. A member (holding wall) 81 is formed (the holding wall 81 is not shown in FIG. 3). In other words, in the illustrated example, the partition wall 42 d extends toward the center of the rotary developing device 4, while the holding wall 81 extends away from the center of the rotary developing device 4.

  Specifically, when the developing chamber 41 is positioned at the developing position (state shown in FIG. 4), the angle α between the horizontal line L and the holding wall 81 with respect to the horizontal line (horizontal direction) L is 0 degree <α The holding wall 81 is provided so as to be <90 degrees. If such a holding wall 81 is formed at the rear end of the partition wall 42d, the toner in the developing chamber 41 is regulated by the holding wall 81, so that the toner is reliably left on the partition wall 42d. The toner can be reliably stored in the developing chamber 41 regardless of the fluidity of the toner.

  In order to reliably store toner in the developing chamber 41, it is desirable to increase the frictional resistance value of the holding wall 81. For example, the surface of the holding wall 81 may be a nonwoven fabric, a woven fabric, a short flange-like member, or a sponge. These members may be pasted. Further, when the holding wall 81 is resin-molded, the surface of the holding wall 81 may be roughened using a texture process or the like to increase the frictional resistance value.

  Furthermore, if the length of the holding wall 81 is adjusted, a large amount of toner can be stored even when a large amount of BK toner is consumed, for example, when a monochrome image is formed. The frequency at which the toner is allowed to flow from the developer storage chamber 42 into the developing chamber 41 by rotating the rotary type developing device 4 again can be reduced. Further, since a large amount of toner can be stored in the developing chamber 41, the toner can be conveyed to the developing roller 47 side by the pressure of the toner itself.

  Further, as described above, when 0 degree <α, toner slippage from the rear end of the partition wall 42d is suppressed, and the toner can be reliably stored in the developing chamber 41. If α <90 degrees, when the rotary developing device 4 is driven to rotate, toner can be prevented from being caught on the rear end side, and the toner in the developer accommodating chamber 42 and the toner in the developing chamber 41 can be reliably Can be mixed.

  In this way, in the illustrated rotary type developing apparatus, the developer amount at the development position where the developing roller 47 faces the photosensitive drum 2, whether the developer amount in the developer storage chamber 42 is large or small. The developer is mixed with the new developer by the rotation of the cylindrical rotary rack 40 and then supplied to the developing chamber, so that there is no adverse effect caused by accumulation of the deteriorated developer.

  In addition, since the powder pressure in the developing chamber 41 does not fluctuate at all, the developer powder pressure increases when the developer remaining amount is large as in the prior art, and conversely the developer powder pressure when the developer remaining amount is small. None of the decrease occurs, and problems such as instability of the developer amount on the developing roller 47 and fluctuations in the developer conveyance amount do not occur. Further, since there is no developer leakage from the restricting part or the seal part, which occurs when the developer remaining amount is large, it is not necessary to increase the seal pressure to cope with them.

  A holding wall that extends upward from the extending direction of the partition wall at the developing position is formed on one end side of the partition wall that defines an opening that communicates the developing chamber and the developer storage chamber. The wall regulates the toner in the developing chamber and ensures that the toner remains on the partition wall, so that the toner can be reliably stored in the developing chamber regardless of the fluidity of the toner. As a result of keeping the powder pressure constant, the present invention can be applied to a color image forming apparatus using a rotary developing device.

1 is a diagram illustrating a schematic configuration of an image forming apparatus including a rotary developing device according to Embodiment 1 of the present invention. FIG. 3 is a perspective view showing a shutter opening / closing mechanism of a developer storage chamber that is detachable in the rotary developing device according to the first embodiment of the present invention. FIG. 10 is a diagram for explaining the movement of the developer in the developing chamber and the developer containing chamber due to rotation of the rotary rack when there is sufficient developer in the developing device. FIG. 2 is an enlarged view showing a developing unit in the rotary type developing apparatus according to Embodiment 1 of the present invention. FIG. 6 is a perspective view showing a state in which a shutter of a developer storage chamber that is made detachable in the rotary type developing device according to Embodiment 1 of the present invention is opened. FIG. 10 is a diagram for explaining the movement of the developer in the developing chamber and the developer accommodating chamber by the rotation of the rotary rack when the developer is reduced in the developing device, and the position where the developer accommodating chamber is replaced.

Explanation of symbols

2 Photosensitive drum 40 Cylindrical rotary rack 41 Developing chamber (developing housing)
41 ₁ Black (BK) developing chamber 41 ₂ Magenta (M) developing chamber 41 ₃ Cyan (C) developing chamber 41 ₄ Yellow (Y) developing chamber 42 Developer accommodating chamber (developer cartridge)
42 ₁ Black (BK) developer accommodating chamber 42 ₂ Magenta (M) developer accommodating chamber 42 ₃ Cyan (C) developer accommodating chamber 42 ₄ Yellow (Y) developer accommodating chamber 43 Shutter 44 Developer 45 Developer Developer 46 in the cartridge Supply roller 47 Development roller 48 Restriction blade 49 Static elimination seal 42d Partition wall 81 Holding wall

Claims (1)

A rotatable rotary rack that is disposed adjacent to and corresponding to a plurality of developing chambers and that contains a developer containing chamber containing a developer, and is disposed on the image carrier disposed in the developing chamber. A developing roller that develops the formed electrostatic latent image; and a supply roller that is disposed in the developing chamber and supplies developer to the developing roller. The developing roller sequentially rotates the image by rotating the rotary rack. In the rotary type developing device positioned at the development position facing the carrier,
The developer storage chamber is detachable from the rotary rack, and is attached to the rotary rack, and the rotation of the rotary rack causes a rotation path of the developing roller to draw the rotary rack from the supply roller. The rotary type is separated from the developing chamber by extending toward the center side, and the rotary type is more than the trajectory drawn by the developing roller by the rotation of the rotary type rack by the partition wall and the rotary type rack. A partition wall provided on the center side of the rack so as to have an opening communicating with the developing chamber and the developer accommodating chamber;
In the development position, the development chamber is located above the corresponding developer storage chamber,
A rotary type developing device, wherein a holding wall is formed on one end side of the partition wall defining the opening at the developing position so as to extend above the extending direction of the partition wall.

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