JP2003263026A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a development ghost, to always secure stable image density, and to obtain an image of high image quality by making developer smoothly flow inside a developing device. <P>SOLUTION: The developing device is provided with a developer carrier 41, a transport screw 43, a stirring screw 44, a peeling roller 45 and a recovering roller 46. A recovering wall member 405 for transporting the developer recovered by the peeling roller 45 to the recovering screw 46 is arranged under the peeling roller 45. The shortest distance d1 in a developer transport area where the member 405 and the roller 45 face each other and the shortest distance d2 in an area where the member 405 and the developer carrier 41 face each other satisfy a condition [d1≥d2]. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, and a multifunctional machine having these functions, and more particularly to an electrostatic latent image formed on an image carrier. The present invention relates to improvement of a developing device for developing an image.

[0002]

2. Description of the Related Art Conventionally known image forming apparatuses such as electrophotographic copying machines charge and expose an image carrier.
Form an electrostatic latent image. The latent image formed on the image carrier becomes a toner image by the developing device, and is transferred onto the sheet by the transfer means. After that, the image is formed by heat fixing with a fixing device.

The developing device develops and visualizes the electrostatic latent image formed on the image carrier using a two-component developer composed of toner and carrier.

The developer whose toner has been consumed after finishing the developing process in the developing area is collected and mixed with the toner to be replenished,
The mixture is agitated and then subjected to development again. The developer used in the developing device having such a structure needs to maintain a constant toner concentration and a constant charge amount in order to obtain a stable toner image. The toner density is determined by the toner consumed in the development and the replenishment toner distribution. The amount of charge is determined by triboelectric charging when the carrier and toner are mixed. The developing device sufficiently stirs the two-component developer consisting of toner and carrier,
The toner image is stabilized by making the toner density distribution uniform and saturating the charge amount applied to the toner.

Consume in a developing screw between a developer carrying member (developing roller) and a conveying screw for supplying the developer to the developing screw, a stirring screw for supplying the developer to the conveying screw by stirring. A developer collecting and conveying roller for peeling and carrying the used developer, which has been used, and a collecting screw for returning the used developer collected by the developer collecting and conveying roller to the stirring screw again.
In a conventional circulation type developing device having a recovery wall member for separating the conveying screw and the developer collecting and conveying roller, and a toner replenishing device, the replenishment toner is introduced into either the stirring screw or the conveying screw, and the stirring screw is used. And the developer is agitated by the transport screw to a uniform concentration and supplied to the developer carrier, and the spent developer consumed in the developing area between the developer carrier and the image carrier is recovered and transported by the developer roller. The toner is peeled off from the developer carrying body by means of, collected by the collecting screw, and returned to the carrying screw to thereby constantly supply the developer carrying the stable toner concentration to the developer carrying body to obtain a toner image.

[0006]

When the used developer on the developer carrying member is peeled off and transferred to the developer collecting / conveying roller, the wall surface of the collecting wall member and the outer peripheral surface of the developer carrying member are removed. If the gap between the wall surface of the collecting wall member and the outer peripheral surface of the developer collecting and conveying roller is not sufficient, the flow of the developer will be stagnated, and the developer of the used low toner concentration will be Part of the material may pass through the gap between the wall surface of the recovery wall member and the outer peripheral surface of the developer carrying member, be carried again on the developer carrying member, and be conveyed to the developing area.

When the used developer is conveyed to the developing area with a low toner concentration, a defect such as a development ghost that affects the image quality occurs.

The present invention solves the above problems and provides a developing device and an image forming apparatus for forming a stable image.

That is, in the developing device of the present invention, in the developing device forming the circulation system of the developer, the distance between the developer collecting roller and the collecting wall member is set to the distance between the developer carrying member and the collecting wall member. By sufficiently ensuring that the developer recovery amount of the developer recovery roller is equal to the developer transport amount of the developer carrier, unused developer is not recovered by the recovery roller, It is prevented from passing through the gap between the developer carrying member and the recovery wall member and being conveyed to the developing area.

Further, with respect to the peripheral linear velocity of the developer carrying member,
Sufficient peripheral linear velocity of the developer collection roller prevents the developer from staying between the developer carrier and the developer collection roller, and the developer on the developer carrier is collected by the developer. Continuously maintain the state of being smoothly transferred to the roller.

As described above, in the developing device for achieving high-speed and high-quality image formation, and in the tandem type color image forming device in which a plurality of developing devices are arranged in a row in the height direction, the image forming unit is made thin by making the developing device thin The purpose is to achieve miniaturization.

[0012]

The above problems can be achieved by the following developing device and image forming apparatus.

(1) A developer carrying member facing an image carrying member carrying an electrostatic latent image, a carrying screw carrying the developer to the developer carrying member, and a developer being stirred by the carrying screw. A stirring screw to be supplied, a developer collecting / conveying roller that collects and conveys the developed developer on the developer carrier, and a developer that has been subjected to the developing treatment collected by the developer collecting / conveying roller. And a recovery screw that conveys the developer to a downstream portion of the non-image forming area of the conveyance screw, and the developer collected by the developer collection conveyance roller is below the developer collection conveyance roller. A recovery wall member that conveys to the recovery screw is installed, and the shortest distance d1 of the developer recovery region where the recovery wall member and the developer recovery transport roller face each other, the recovery wall member and the A developing device characterized in that the shortest distance d2 of the region facing the developer carrying member satisfies the following condition.

D1 ≧ d2 (2) A developer carrying body facing the image carrying body carrying the electrostatic latent image, a carrying screw carrying the developer to the developer carrying body, and a developer carrying the carrying screw. A stirring screw for stirring and supplying, a developer collecting / conveying roller for collecting and conveying the developer having undergone the developing treatment on the developer carrying member, and a developing-processed developer collected by the developer collecting / conveying roller. In a developing device having a collecting screw that collects and conveys the developer to a downstream portion of the non-image forming region of the conveying screw, a linear velocity V1 of the outer peripheral surface of the developer collecting and conveying roller and a developer carrying member Peripheral surface linear velocity V
2 is a developing device characterized by satisfying the following conditions.

V1 ≧ V2 (3) In the above (1) or (2) containing a plurality of charging means for forming an electrostatic latent image on the image bearing member, a plurality of exposing means, and developers of different colors, respectively. A plurality of developing devices described above, a transfer unit that transfers toner images of a plurality of colors formed by the plurality of developing devices to a recording sheet, a sheet feeding unit that feeds the recording sheet to the transfer unit, and a recording sheet on the recording sheet. An image forming apparatus comprising: a fixing unit configured to fix the transferred image formed on the image forming apparatus.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Prior to the description of an embodiment of a developing device of the present invention, the structure of a color copying machine, which is an example of an image forming apparatus in which a plurality of developing devices of the present invention are mounted, will be described.

[Arrangement of Image Forming Apparatus] FIG. 1 is an overall arrangement view of a color copying machine including an image forming apparatus 100 and an image reading apparatus 200.

The image forming apparatus 100 is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C and 10K, a belt-shaped intermediate transfer member 6, a sheet feeding / conveying means and a fixing unit. And a device 24.

Image forming section 1 for forming a yellow image
0Y is a charging unit 2 arranged around the image carrier 1Y.
Y, exposure means 3Y, developing device 4Y, cleaning means 8
Have Y. Image forming unit 1 for forming a magenta image
0M is an image carrier 1M, a charging unit 2M, an exposure unit 3M,
It has a developing device 4M and a cleaning means 8M. The image forming unit 10C that forms a cyan image is the image carrier 1
C, charging means 2C, exposure means 3C, developing device 4C, and cleaning means 8C. The image forming unit 10K that forms a black image includes an image carrier 1K, a charging unit 2K, an exposing unit 3K, a developing device 4K, and a cleaning unit 8K.
The intermediate transfer body 6 is wound by a plurality of rollers and is rotatably supported.

Image forming units 10Y, 10M, 10C, 10
The image of each color formed by K is rotated by the intermediate transfer member 6
The transferred color images are sequentially transferred (primary transfer) by the transfer units 7Y, 7M, 7C, and 7K to form a combined color image. The paper P stored in the paper feed cassette 20 is fed by the paper feed means 21 and fed by the paper feed rollers 22A, 22B, 2
The color image is transferred to the transfer unit 7A via the 2C, the registration roller 23 and the like, and the color image is transferred onto the paper P (secondary transfer). The paper P on which the color image is transferred is fixed by the fixing device 24.
Then, the sheet is fixed by the sheet ejection roller 25, is sandwiched by the sheet ejection rollers 25, and is placed on the sheet ejection tray 26 outside the apparatus.

On the other hand, after the color image is transferred onto the paper P by the transfer means 7A, the intermediate transfer body 6 is obtained by separating the curvature of the paper P.
The residual toner is removed by the cleaning unit 8A.

5Y, 5M, 5C and 5K are developing devices 4.
It is a toner replenishing means for replenishing Y, 4M, 4C, and 4K with new toner.

An image reading device 200 including an automatic document feeding device 201 and a document image scanning exposure device 202 is installed above the image forming apparatus 100.

[Structure of Developing Device] FIG. 2 is a central sectional view of the developing device according to the present invention, FIG. 3 is a perspective view of the developing device, and FIG.
FIG. 4A is a plan view of the upper mechanism of the developing device, FIG. 4B is a plan view of the lower mechanism of the developing device, and FIG. 5 is a schematic diagram showing the circulation of the developer in the developing device. Hereinafter, the developing device 4Y,
4M, 4C, and 4K are typically called the developing device 4.

The developing device 4 includes a developing device main body 40, a developer carrying member (developing roller) 41, a developer regulating member (ear cutting plate) 42, a conveying screw 43, a stirring screw 44,
Developer recovery transport roller (hereinafter referred to as peeling roller)
45, a recovery screw 46, a toner concentration sensor (toner concentration detecting means) 47 and the like.

The developing device main body 40 includes a developer carrier 41,
Lower main body 40A supporting the conveying screw 43 and the stirring screw 44, the peeling roller 45, and the recovery screw 4
It is composed of a middle body 40B that supports 6 and an upper lid 40C that closes the upper opening of the middle body 40B.

The lower main body 40A comprises a developer supplying section 401 for accommodating the conveying screw 43 and a developer stirring section 402 for accommodating the stirring screw 44. Developer supply section 4
01 and the developer stirring section 402 are formed on both sides with the first partition wall 404 standing upright from the bottom of the lower body 40A.

A second partition wall (also referred to as a recovery wall member) 405 formed at the bottom of the main body 40B for rotatably supporting the recovery screw 46 partitions the developer supply section 401 and the developer recovery section 403. Further, a part of the middle main body 40B closes the upper opening of the developer stirring section 402.

The developer carrying member 41 consisting of the developing sleeve 41A and the magnetic field generating means (magnet roll) 41B is
It is arranged so as to face the image carrier 1 that carries the electrostatic latent image, and is rotatably supported.

The magnetic field generating means 41B is a developing sleeve 41.
A plurality of magnetic poles N1, N2, N3, N arranged inside A
4, S1, S2, S3. Two magnetic poles N3 and N4 that are adjacent to each other among the plurality of magnetic poles of the magnetic field generating means 41B.
Are arranged with the same polarity and form a repulsive magnetic field. The developer stripping magnetic pole N3 strips and scatters the developer on the developer carrier 41. Magnetic pole N4 for receiving developer
Sucks the developer supplied by the conveying screw 43 and attaches it onto the developer carrier 41.

The conveying screw 43 is the stirring screw 4
The developer conveyed from No. 4 is stirred and conveyed, and is uniformly supplied to the developer carrying member 41.

The stirring screw 44 is the conveying screw 43.
And the new toner replenished from the toner replenishing means 5 and the developer recirculated from the recovery screw 46 are mixed, stirred, and conveyed to the upstream portion of the conveyance screw 43.

A stripping roller 45 is arranged near the magnetic pole N3 for stripping the developer on the developer carrying member 41. The stripping roller 45 is composed of a rotatable rotating member (sleeve) 45A and a cylindrical magnet roller (magnet body) 45B housed inside the rotating member 45A and fixed to the developing device main body 40. The magnet body 45B is composed of, for example, three magnetic poles N1, S1, and S2, and the magnetic pole S1 faces the magnetic pole N3 for stripping the developer of the developer carrier 41.

The developer released from the surface of the developer carrying member 41 by the developer removing magnetic pole N3 of the developer carrying member 41 is sucked by the magnetic pole S1 in the removing roller 45, and rotates the rotating member 45A. And is conveyed on the inclined second partition wall 405 in the developer collecting section 403.

The collecting screw 46 rotatably arranged in the developer collecting section 403 receives and collects the developer which is peeled off by the peeling roller 45 and falls, and the stirring screw in the developer stirring section 402. The toner is conveyed to the outside of the developing area of the developer carrying member 41 on the downstream side of the conveying direction of 44.
Note that the developer recovered by the recovery screw 46 may be returned to the upstream portion of the developer supply unit 401 at a position where the developer does not directly return to the developer carrier 41.

Conveying screw 43, stirring screw 4
4. The recovery screw 46 is a spiral screw-shaped member, and conveys the developer in the direction of the rotating shaft and releases the developer in the direction substantially perpendicular to the rotating shaft.

The developer transporting portion downstream side of the developer collecting portion 403 and the developer transporting downstream portion of the developer supplying portion 401 are the second
The first opening 406 is formed in the vicinity of the end of the partition wall 405 to communicate with each other.

A second opening 407 is formed in the vicinity of one end of the first partition wall 404 on the downstream side of the developer transport of the developer supply section 401 and on the upstream side of the developer transport of the developer stirring section 402.
Are in communication with each other.

The developer transporting downstream side of the developer stirring section 402 and the developer transporting upstream side of the developer supply section 401 are provided with a third opening 408 formed near the other end of the first partition wall 404.
Are in communication with each other.

A toner concentration sensor 47 provided at the bottom of the developer supply unit 401 on the downstream side of the developer transport detects the toner concentration of the transported developer. In response to the toner concentration detection signal, the control unit drives the toner replenishment unit 5 to replenish new toner to the toner replenishment opening 409 provided near the developer transport upstream side of the developer stirring unit 402. The toner replenishing means 5 can also optically detect the image density after the development processing and perform toner replenishment control according to the detection result of the image density.

The developer stripped off by the stripping roller 45 is recovered in the developer recovery section 403, and the recovered developer is transported to the downstream side of the developer transport by the recovery screw 46, and the second partition wall 405 is perforated. The flow is returned from the first opening 406 thus formed to the downstream side of the developer transport inside the developer supply unit 401.

The developer in the developer supply unit 401 is transported from the second opening 407 formed at one end of the first partition 404 by the transport screw 43 to the developer transport upstream side in the developer stirring unit 402. Be transported to.

The developer conveyed into the developer agitating section 402 is supplied to the toner replenishing opening 4 by the agitating screw 44.
09, the new toner replenished by the developer and the developer are mixed and agitated and conveyed, discharged from the third opening 408 formed at the other end of the first partition wall 404, and supplied to the developer supply unit 40.
It is refluxed in 1. In the developer supply unit 401, the developer is radiated while being transported in the axial direction by the transport screw 43 and is supplied to the developer carrier 41.

Developer collecting section 403 and developer supplying section 401
The first partition provided near the end of the second partition 405 for partitioning
The opening 406, the second opening 407 and the third opening 408 provided near both ends of the first partition wall 404 that divides the developer supply unit 401 and the developer stirring unit 402 are both the developer carrier. It is preferably arranged in 41 non-image forming areas.

Conveying screw 43 and stirring screw 44
The rotational direction of the developer carrying member 41 is the same as the rotating direction of the developer carrying member 41, so that not only efficient developer supply to the developer carrying member 41 but also stable developer Supply is possible, and good images can be obtained.

The direction of rotation of the recovery screw 46 is
By rotating the developer carrier 41 in the opposite direction to the rotation direction, it is possible to reduce the reverse flow of the developer in the developer collecting section 403. Further, the developer carrying force of the recovery screw 46 is set to be smaller than the developer carrying force of the carrying screw 43. This allows the recovery screw 4
It is possible to prevent the occurrence of developer packing on the downstream side of the developer transporting direction of 6, and it is possible to stably supply the developer to the developer carrier 41 without impairing the durability of the developer.

In the developer, the amount of magnetization in 1 kilo-oersted magnetic carrier is in the range of 20 to 70 emu / g, and the particle size of the magnetic carrier is in the range of 30 to 80 μm, and the particle size is 3. Is a two-component developer having a non-magnetic toner in the range of ˜8 μm.
A developing bias in which an alternating electric field is superimposed on 1 is applied, and the image carrier 1 having an electrostatic latent image is developed using the non-magnetic toner.

[Conveyance Circulation of Developer] The circulation of the developer will be described with reference to the schematic diagram of FIG.

(1) On the upstream side of the developer stirring section 402, the developer refluxed from the developer supply section 401 and the developer recovery section 403 and the new toner are carried in and stirred and mixed by the stirring screw 44. , And is conveyed in the developer moving direction indicated by arrow X1.

(2) The mixed developer passes through the third opening 408 on the downstream side of the developer stirring section 402 and is introduced on the upstream side of the developer supply section 401. Developer supply unit 40
In 1, the developer is carried by the carrying screw 43 in the developer moving direction shown by the arrow X2, and is carried as shown by the arrow X3.

(3) The conveying screw 43 conveys the developer in the rotation axis direction and discharges the developer to the developer carrier 41 as shown by an arrow X4.

(4) The developer on the developer carrying member 41 is
Development processing is performed in the developer region facing the image carrier 1. The developer whose toner concentration has decreased after the development processing is removed by the peeling roller 45 from the developer carrying member 41 in the direction of arrow X5.
It is stripped and moved as shown in.

(5) The collected developer on the stripping roller 45 descends along the inclined surface of the second partition wall 405, and the arrow X
As shown in FIG.

(6) The recovered developer contained in the developer recovery section 403 is conveyed by the rotating recovery screw 46 as shown by arrow X7.

(7) The recovered developer is stored in the developer recovery section 40.
3 is discharged from the first opening 406 on the downstream side, and is carried in outside the image area on the downstream side of the developer supply unit 401 as shown by an arrow X8.

(8) The developer supplied to the first opening 406 of the developer supply unit 401 is conveyed as shown by an arrow X9, and after the toner density is detected by the toner density sensor 47, the second opening is opened. After passing through the section 407, it is introduced to the upstream side of the developer stirring section 402 as shown by an arrow X10.

(9) In the developer stirring section 402, the toner replenishment means 5 replenishes the toner by the toner concentration detection signal of the toner concentration sensor 47, and the developer is indicated by the arrow X.
Merge into 1.

The developer is conveyed by the circulation system as described above, but a part of the developer is circulated between the developer supply section 401 and the developer stirring section 402 as indicated by arrows X1, X2, X9, and X10. To do.

[Recovery Wall Member] Below the stripping roller 45, a recovery wall member 405 for transporting the developer collected by the stripping roller 45 to the recovery screw 46 is installed. The upper surface side of the recovery wall member 405 is formed as an inclined surface. The developer stripped off by the stripping roller 45 descends on the inclined surface in the direction of the white arrow and advances toward the recovery screw 46.

The shortest distance d1 of the developer collecting area where the upper surface of the collecting wall member 405 and the outer peripheral surface of the stripping roller 45 face each other is the shortest distance of the area where the collecting wall member 405 and the developer carrier 41 face each other. It is set larger than d2 (see FIG. 2, d1 ≧ d2).

FIG. 6A is a characteristic diagram of the amount of developer recovered by the recovery screw 46. When the developer carrying amount of the developer carrying member 41 is Q [g / min] and the developer carrying amount of the recovery screw 46 is q1 [g / min], FIG.
As shown in (a), d1 / d2 ≧ 1, that is, d1 ≧ d
By setting it to 2, q1 / Q = 1, that is, the developer carrying member 4
The used developer that has been conveyed by 1 is collected by the recovery wall member 4
05 and the developer carrying member 41 do not flow in a region where they oppose each other, and the stripping roller 45 smoothly collects the recovery screw 46.
It is prevented that the developing agent flows to the used developer, and the used developing agent whose toner concentration is lowered is not used again for the direct development, and a stable and uniform high quality image is obtained.

Here, the shortest distance d1 is 1.0 to 3.0.
mm, the shortest distance d2 is preferably 0.5 to 1.5 mm. In the present embodiment, for example, d1 is 2.0
By setting mm and d2 to 1.0 mm, it was confirmed that the above effect was obtained.

By setting the shortest distances d1 and d2 as described above, the developer carrying member 4 is removed by the stripping roller 45.
The developer peeled off from No. 1 is conveyed by the rotating member 45A of the rotating peeling roller 45, and is collected by the collecting wall member 40.
It was confirmed that the recovery screw 46, which descends along the upper surface side of the rotating member 45A of No. 5, can be recovered by the rotating recovery screw 46.

Further, the rotating member 45 of the stripping roller 45
The linear velocity V1 of the outer peripheral surface of A is set to be higher than the linear velocity V2 of the outer peripheral surface of the developing sleeve 41A of the developer carrier 41 (V
1 ≧ V2).

FIG. 6B is a characteristic diagram of the amount of developer collected by the stripping roller 45. When the developer carrying amount of the developer carrying member 41 is Q [g / min] and the developer carrying amount of the peeling roller 45 is q2 [g / min], FIG.
As shown in (b), V1 / V2 ≧ 1, that is, V1 ≧ V
By setting it to 2, q2 / Q = 1, that is, the developer carrier 4
The used developer conveyed by 1 is the developer carrier 4
1 is smoothly conveyed by the stripping roller 45 without staying between the stripping roller 45 and the stripping roller 45, and the occurrence of defects such as depletion of the developer is prevented.

The linear velocity V1 of the outer peripheral surface of the peeling roller 45 is 330 to 610 mm / sec, and the developer carrier 4 is
The linear velocity V2 of the outer peripheral surface of No. 1 is 330 to 510 mm / sec
In the present embodiment, for example, V1
It was confirmed that the above-mentioned effects were obtained by setting V.sub.2 to 460 mm / sec and V2 to 460 mm / sec.

By setting the shortest distances V1 and V2 in this way, the developer does not stay in the developer stripping area, and almost all the stripped developer is conveyed by the stripping roller 45. And is collected by the collecting screw 46.

Further, by making the rotating direction of the developer carrying member 41 and the rotating direction of the rotating member 45A of the peeling roller 45 opposite to each other, the developer carrying member 41 and the peeling roller 45 face each other. Development sleeve 4 in the take-off area
1A and the rotating member 45A are driven in the same tangential direction,
The developer can be stripped off and transported smoothly.

In this embodiment, for example, d1 is 2.0
mm, d2 is 1.0 mm, and V1 is 460 mm
/ Sec, V2 is 460 mm / sec, V1 ≧ V
By setting the value to 2, it is possible to smoothly convey and collect the used developer whose toner concentration has decreased even at high speed and during continuous printing, and prevent problems such as toner concentration reduction and image concentration reduction. The effect was confirmed.

That is, the shortest distance of the developer transport area is d1 ≧
In d2, the linear velocity is set to V1 ≧ V2, and the rotational tangential directions in the stripping region of the developer carrying member 41 and the stripping roller 45 are made the same, so that the developer of the circulation type developing device 4 is The stripping and conveyance of the toner are carried out smoothly, and a part of the used low-toner-concentration developer is partially recovered.
It is prevented that an image defect such as a development ghost is generated by passing through the gap between the wall surface of the developer carrier 41 and the outer peripheral surface of the developer carrier 41, being supplied again onto the developer carrier 41 and conveyed to the developing area. It is possible to form high quality images.

[0071]

The developing device and the image forming apparatus of the present invention have the following effects.

(1) Unused developer is prevented from being supplied to the developer carrier while the toner concentration remains low, the developer transport amount is secured regardless of the printing rate, and the image density is always stable. Therefore, it is possible to always obtain a stable and uniform high-quality image without causing a problem of uneven density such as a development ghost.

(2) The flow of the developer in the circulation type developing device becomes smooth, and problems such as developer packing and developer depletion are prevented.

(3) Problems such as toner density reduction and image density reduction that occur during continuous large volume printing or high speed printing are solved.

(4) The image density of each color in the color image forming apparatus can be kept uniform and a high quality color image can be obtained.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a color copying machine including an image forming apparatus and an image reading apparatus.

FIG. 2 is a central sectional view of a developing device according to the present invention.

FIG. 3 is a perspective view of a developing device.

FIG. 4 is a plan view of an upper mechanism of the developing device and a plan view of a lower mechanism of the developing device.

FIG. 5 is a schematic diagram showing circulation of a developer in a developing device.

FIG. 6 is a characteristic diagram of a developer recovery amount by a recovery screw,
And FIG. 9 is a characteristic diagram of the amount of developer collected by the stripping roller.

[Explanation of symbols] 4,4Y, 4M, 4C, 4K Developing device 10Y, 10M, 10C, 10K Image forming unit 100 image forming apparatus 40 Developing device main body 40A lower body 40B main body 401 developer supply unit 402 developer stirring section 403 Developer Collection Section 405 Second partition wall (collection wall member) 41 developer carrier (developing roller) 41A developing sleeve 41B Magnetic field generating means (magnet roll) 43 Conveyor screw 44 stirring screw 45 Developer Recovery Conveying Roller (Stripping Roller) 45A rotating member (sleeve) 45B Magnet roller (magnet body) 46 Recovery screw d1, d2 shortest distance

Claims (5)

[Claims] 1. A developer carrying member facing an image carrying member carrying an electrostatic latent image, a carrying screw carrying the developer to the developer carrying member, and a developer being stirred and supplied to the carrying screw. A stirring screw, a developer collecting / conveying roller that collects and conveys the developed developer on the developer carrying member, and collects the developing-processed developer collected by the developer collecting / conveying roller. And a recovery screw which conveys the developer to a downstream portion of the non-image forming area of the conveyance screw, and the developer collected by the developer collection and conveyance roller is collected below the developer collection and conveyance roller. A recovery wall member that conveys to the screw is installed, and the shortest distance d1 of the developer recovery area where the recovery wall member and the developer recovery transport roller face each other, the recovery wall member and the developer A developing device characterized in that the shortest distance d2 of the region facing the carrier satisfies the following condition. d1 ≧ d2 2. The developing device according to claim 1, wherein the rotation direction of the developer carrying member and the rotation direction of the developer collecting and conveying roller are opposite to each other. 3. A developer carrying member facing an image carrying member carrying an electrostatic latent image, a carrying screw carrying the developer to the developer carrying member, and a developer being stirred and supplied to the carrying screw. A stirring screw, a developer collecting / conveying roller that collects and conveys the developed developer on the developer carrying member, and collects the developing-processed developer collected by the developer collecting / conveying roller. In a developing device having a collecting screw that conveys to the downstream portion of the non-image forming area of the conveying screw, a linear velocity V1 of the outer peripheral surface of the developer collecting and conveying roller and a line of the outer peripheral surface of the developer carrying member. A developing device characterized in that the speed V2 satisfies the following conditions. V1 ≧ V2 4. The rotation direction of the developer carrying member and the rotation direction of the developer collecting and conveying roller are oppositely driven and rotated, and the following condition is satisfied. The developing device described. V1 ≧ V2 where V1 is the linear velocity of the outer peripheral surface of the developer collecting / conveying roller, and V2 is the linear velocity of the outer peripheral surface of the developer carrier. 5. A plurality of charging means for forming an electrostatic latent image on an image bearing member, a plurality of exposing means, and developers of different colors are housed, respectively. A plurality of developing devices, a transfer unit that transfers the toner images of the plurality of colors formed by the plurality of developing devices onto a recording sheet, a sheet feeding unit that feeds the recording sheet to the transfer unit, and a forming unit formed on the recording sheet. An image forming apparatus comprising: a fixing unit configured to fix the transferred image.