JP2003330268A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrences of toner spilling and image staining in a developing device in the case of reusing residual toner after transfer recovered by a cleaning device for image forming by recycling to reflux to the developing device. <P>SOLUTION: In an image forming apparatus comprising the developing device 4, the cleaning device 6 and a toner recycling device, the shape of a bottom surface wall on the lower side of the developing roller 41 of a developing device main body 40 housing the developing roller 41 is formed into a surface having a difference in level in which an interval between outer peripheral surfaces near both ends of the developing roller 41 in a longitudinal direction and the bottom surface wall 40D is larger than an interval between an outer peripheral surface near the image forming area of the developing roller 41 and the bottom surface wall 40C. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner image formed on a surface of an electrostatic latent image carrier by a developing device, the toner image being transferred to a recording sheet by a transfer device, and the image carrier having passed through a transfer position. The present invention relates to an image forming apparatus in which a transfer residual toner adhering to the surface of a body is removed by a cleaning device, and the removed transfer residual toner is returned to a developing device by a toner recycling device for reuse.

[0002]

2. Description of the Related Art In recent years, the need for high-quality, high-speed image forming apparatuses based on digital technology has increased with the progress of advanced information technology. Further, the amount of hard copies printed on paper tends to increase more and more, and social demand for an image printing apparatus capable of printing with energy saving and resource saving is increasing. In order to meet these demands, the following technologies have been developed and introduced, and further problems have been created.

A developer having a smaller particle diameter is used for higher image quality, and printing is performed at high speed. The problem that occurs here is that as the toner surface area increases with the reduction in particle size, the developer charge amount rises insufficiently due to frictional charging with the carrier, and if printing is performed at higher speeds, replenishment is replenished. Since the developer is used for image formation in a short time, the proportion of the developer whose charge amount of the developer does not rise sufficiently tends to increase.

To save energy and resources, the developer used once for image formation is recycled and repeatedly used for image formation. The problem that occurs here is that the recycled developer causes fluidity deterioration and electrical property deterioration once it is used for image formation, and the developer charge amount does not rise sufficiently due to frictional charging property deterioration. Easy to increase.

As a result of the above-mentioned problems, the electrostatic attraction between the carrier and the toner weakens, the toner is released from the carrier in the developing device, and the free toner accumulates at the bottom of the developing device main body and accumulates. Problems such as "toner spilling" in which toner spills out of the developing device main body and "image dirt" in which spilled toner adheres to an image occur.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems and retains free toner in the developing device main body or sucks the developer by suction means until the developer is replaced in the developing device. Therefore, even when the developer is recycled and used, it is an object of the present invention to provide an image forming apparatus capable of preventing “spilling of toner” and “dirt of image” and realizing high image quality, high productivity, energy saving and resource saving. To do.

[0007]

The above-mentioned problems can be solved by the following image forming apparatus of the present invention.

(1) The electrostatic latent image formed on the electrostatic latent image bearing member is developed and visualized by using the developer layer carried on the developer bearing member of the developing device, and the visualized image is formed. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by a transfer device and the image is repeatedly formed, a developing process for accommodating the developer carrier is carried out. The shape of the bottom wall below the developer carrier of the apparatus main body is such that the distance between the outer peripheral surface near both ends in the longitudinal direction of the developer carrier and the bottom wall is near the image forming area of the developer carrier. An image forming apparatus, wherein the stepped surface is formed to be larger than the distance between the outer peripheral surface and the bottom wall.

(2) The electrostatic latent image formed on the electrostatic latent image carrier is developed and visualized by using the developer layer carried on the developer carrier of the developing device, and the visualized image is displayed. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by a transfer device and the image is repeatedly formed, a developing process for accommodating the developer carrier is carried out. The shape of the bottom wall below the developer carrier of the apparatus main body is such that the distance between the outer peripheral surface near both ends in the longitudinal direction of the developer carrier and the bottom wall is near the image forming area of the developer carrier. An opening for connecting to a suction duct is formed in the bottom wall of the developing device main body, which is formed on a step surface larger than the distance between the outer peripheral surface and the bottom wall and faces the outer peripheral surface near both ends in the longitudinal direction of the developer carrier. Image form characterized by having Equipment.

(3) The electrostatic latent image formed on the electrostatic latent image carrier is developed and visualized by using the developer layer carried on the developer carrier of the developing device, and the visualized image is formed. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by a transfer device and the image is repeatedly formed, a developing process for accommodating the developer carrier is carried out. An image forming apparatus having an opening connected to a suction duct at a bottom portion of the developing device main body from a lower portion of the developer carrying body of the apparatus main body to a tip of the developer carrying body opening portion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an image forming apparatus equipped with a developing device and a toner recycling device of the present invention will be described with reference to the drawings.

[Embodiment of Image Forming Apparatus] FIG. 1 is an overall configuration diagram of the image forming apparatus A.

In the image forming apparatus A, a charging device 2 is provided around a rotating electrostatic latent image carrier (hereinafter referred to as an image carrier) 1.
Image exposure device (image writing unit) 3, developing device 4, transfer device 5
It has an image forming unit in which A, the static eliminator 5B, and the cleaning device 6 are arranged. The image forming unit uniformly charges the surface of the image carrier 1 by the charging device 2 and then performs exposure scanning based on the image data read from the original by the laser beam of the image exposure device 3 to form a latent image. Then, the latent image is reversely developed by the developing device 4 to form a toner image on the surface of the image carrier 1.

On the other hand, the sheet feeding cassettes 7A, 7B arranged in the middle stage of the image forming apparatus A, the large-capacity sheet feeding trays 7C, 7D arranged in the lower stage, the manual sheet feeding tray 7E arranged at the side, and the like are supplied. Recorded recording paper (hereinafter referred to as paper) S
Is sent to the transfer position via the registration roller 7F.

At the transfer position, the toner image is transferred onto the paper S by the transfer device 5A. After that, the electric charge on the back surface of the sheet S is erased by the static eliminator 5B and the image carrier 1
The sheet is separated from the sheet, is heated and fixed by the fixing device 8, is conveyed by the reverse conveying section 9C, and is discharged by the sheet discharge roller 9A.

When images are formed on both sides of the paper S,
The sheet S heat-fixed by the fixing device 8 is branched from the normal sheet discharge path by the conveyance path switching plate 9B, switched back and turned upside down in the reversing conveyance section 9C, and then passes through the image forming section again. Form an image on the back of S,
After passing through the fixing device 8, the paper is ejected outside the device by the paper ejection roller 9A.

On the other hand, the surface of the image carrier 1 after image processing is
The cleaning device 6 removes the developer remaining on the surface to prepare for the next image formation.

FIG. 2 is a sectional view showing an embodiment of the image forming portion arranged around the image carrier 1.

[Developing Device] In FIG. 2, the developing device 4
Is a developing device main body 40 that contains a two-component developer composed of toner and a carrier, and a developer bearing member that is rotatably supported by the developing device main body 40 and rotates in a counterclockwise direction (hereinafter referred to as a developing roller). 41, a paddle-shaped developer supply member (hereinafter, referred to as a paddle wheel) 42 that is driven to rotate to supply the developer to the developing roller 41, and a screw shape that drives and rotates to stir the developer and convey the developer to the paddle wheel 42 A developer stirring / conveying member (hereinafter referred to as a stirring screw) 43, 44, a developer layer thickness regulating member (hereinafter referred to as a regulating blade) 45 for regulating the developer layer thickness on the developing roller 41 to a predetermined amount, A toner replenishing device 47 for replenishing new toner into a developer stirring chamber 46 having a stirring screw 44 is constituted.

The developer contained in the developing device main body 40 is agitated by the agitating screws 43 and 44, so that the toner and the carrier are triboelectrically charged in opposite polarities. This developer is carried and conveyed on the developing roller 41 to which a bias voltage having the same polarity as the charging polarity of the toner is applied. The developer whose layer thickness is regulated by the regulation blade 45 is carried to the developing area between the developing roller 41 and the image carrier 1. In this developing area, the toner in the developer is electrostatically transferred to the electrostatic latent image formed on the surface of the image carrier 1, and the electrostatic latent image is visualized as a toner image.

When a toner concentration sensor 48 detects that the toner concentration of the developer contained in the developing device main body 40 has decreased, the toner replenishing device 47 is operated and the toner contained in the toner container is removed. It is replenished in the main body 40.

[Cleaning Device] Cleaning Device 6
Is a cleaning blade 61 and a toner guide roller 6
2. The toner conveying screw 63.

The transfer residual toner adhering to the surface of the image bearing member 1 is removed from the surface of the image bearing member 1 by the cleaning blade 61 of the cleaning device 6, guided by the toner guide roller 62, and the toner conveying screw 63. The collected toner is further conveyed to the developing device 4 by the toner recycling device.

[Toner Recycling Device] The transfer residual toner collected by the toner carrying screw 63 is carried diagonally upward by the collected toner carrying screw 65 rotating in the collected toner guide tube 64 connected to the toner carrying screw 63, and developed. It is sent to the recycled toner supply port 40A of the apparatus main body 40.

[Examples] -Developer: polymerized toner (styrene-acrylic, particle size 6,
9, 11, 14 μm) Ferrite carrier (silicone resin coat, particle size 6
Image forming apparatus: Experimental machine Konica 7065 remodeling machine (monochrome, digital copier / printer, 600 dpi (where dpi indicates the number of dots per 2.54 cm),
Laser beam diameter main scanning 55 μm / sub scanning 80 μm),
Toner recycling mechanism available ・ Experimental environment: Temperature 20 ° C ・ Humidity 50% RH ・ Paper type: Plain paper Konica Copy J Paper (registered trademark), A4 size paper original A4 size paper, characters with blackening rate 6% Chart / Evaluation Method (1) Toner Spill: Check for toner spill from the opening near the developing roller 41 of the developing device body 40. After the image forming process was performed up to the life of the developer (about 250,000 sheets printed), the state of occurrence of toner spill from the opening of the developing device main body 40 was visually judged. About 50 if necessary
After performing the image forming process up to the printing of 10,000 sheets, the state of occurrence of toner spill was confirmed.

No toner spillage from the developing device 4; “◯” Scattered toner adhered to the outside of the outer wall of the developing device body 40, but no toner spilling outside the developing device 4; “Δ” Occurrence of toner spill on the outside; “×” (2) Image stain: The image sample during image formation was visually confirmed, and the visual check was intermittently continued up to 250,000 sheets of the maintenance cycle for determination.

(3) Reproducibility of isolated dot: An isolated dot image of 1 dot is formed and evaluated by visually observing the dot shape and diameter with a magnifying glass.

First Embodiment Developing Device FIG. 3 (a) is a front sectional view of a conventional developing device, FIG. 3 (b).
FIG. 6 is a sectional view taken along line AA.

The bottom wall 40B of the developing device main body 40 of the conventional developing device 4 is formed in the same gap parallel to the outer peripheral surface of the developing roller 41 in the axial direction.

FIG. 3C is a front sectional view of the developing device of the present invention, and FIG. 3D is a sectional view taken along line AA.

In the bottom wall of the developing device main body 40 of the developing device 4 of the present invention, the distance between the outer peripheral surface near the axial ends of the developing roller 41 and the bottom wall 40D is the outer circumference near the image forming area of the developing roller 41. The groove shape is larger than the distance between the surface and the bottom wall 40C. An opening 40E connected to the suction duct is formed near both ends of the bottom wall 40D.

Experimental equipment: Digital copier / printer Si
thios7065 (registered trademark) remodeling machine (see FIG. 1).

Experimental conditions: Linear velocity ratio (V _S / V _P ) between the developing roller 41 and the image carrier 1 at the time of image output = 2.0, toner density: 4.5 to 5.2%, toner Particle size: 6 μm, recycled toner is continuously returned to the developing device 4 while the image carrier 1 is rotating, experimental environment: normal temperature, normal humidity (20 ° C., 50% RH), 6% printing rate character chart Then, the image stain was evaluated by visually confirming the image sample by intermittently continuing the image forming process until the developer life of 250,000 copies.

Experimental results of the first embodiment Different bottom walls 40B, 40C, 40 of the developing device main body 40
Table 1 shows the results of actual measurement of toner spills and image stains with respect to D.

[0035]

[Table 1]

In the case of the conventional developing device 4 in which the bottom wall 40B of the developing device main body 40 has a uniform gap (no concave groove) (see FIG. 3A), before the life of the developer reaches 250,000 copies. At the same time, toner spills and image stains occurred (marked with X).

That is, in the developing device 4, the free toner released from the carrier rides on the wind from the vicinity of the center of the bottom of the developing device main body 40 and advances in the direction of the arrow shown in FIG. Collect near the section. As copying progresses, the amount of accumulated toner increases, and the toner flows out through the opening on the developing roller 41 side of the developing device main body 40 to the outside. Occur.

Bottom walls 40C and 40D of the developing device main body 40
In the case of the developing device 4 of the present invention in which the gaps (concave grooves) differ in the axial direction of the developing roller 41 to form a step (FIG. 3C)
(Refer), toner spills and image stains do not occur by the developer life of 250,000 copies (marked with a circle). That is, by accumulating the free toner in a wide space portion having a large gap between both ends of the developing roller 41, it is possible to prevent the occurrence of problems such as toner spill and image stain.

[Second Embodiment] In the case of the conventional developing device 4 having the bottom wall 40B of the developing device main body 40 formed in the same gap parallel to the outer peripheral surface of the developing device developing roller 41 in the axial direction. Then, the influence of the toner particle size in the case of the developing device 4 of the present invention in which the opening 40E connected to the suction duct is formed near both ends of the developing roller 41 in the axial direction was comparatively examined.

-Experimental machine: Digital copier / printer Si
thios7065 (registered trademark) remodeling machine (see FIG. 1).

Experimental Conditions In the conventional example and the first embodiment, the reproducibility of toner spills and isolated dots was investigated by changing the toner particle size.

The developing roller 41 and the image carrier 1 at the time of image output.
And linear velocity ratio (V _S / V _P ) = 1.5, toner concentration: 4.5 to 5.2%, toner volume average particle diameter: 6, 9, 11, 14 μm, recycled toner is the developing device 4 To the image carrier 1 continuously during rotation, experimental environment: normal temperature, normal humidity (20 ° C., 50% RH), copy a 6% printing rate character chart, and image stains with the image sample as a developer. The life count was visually confirmed up to 250,000 copies and up to 500,000 copies.

Toner spills were visually confirmed after every 50,000 sheets, and finally, the in-machine stain was visually confirmed and judged continuously until the life of the developer reached 250,000 sheets.

Experimental Results of the Second Embodiment Table 2 shows the results of examining the reproducibility of toner spills and isolated dots depending on the presence or absence of the opening 40E on the bottom wall of the developing device main body 40.

[0045]

[Table 2]

In the case of the conventional developing device 4 in which the bottom wall 40B of the developing device main body 40 has a uniform gap (see FIG. 3A), a small particle size (6 to 11 μm) which is disadvantageous in charging rise.
In the case of the toner of No. 3, toner spillage is likely to occur (x mark, △
mark).

In the case of the developing device 4 of the present invention which has an opening 40E near the bottom wall 40D of the developing device main body 40 and is connected to a suction duct (see FIG. 3C), a small particle size (6 to 14).
It is possible to prevent the occurrence of toner spill by sucking and removing the free toner even for the toner of (μm) (marked with ◯).

In particular, when the toner particle size is 9 μm or less, the toner spill will occur even if 500,000 copies, which is twice as long as the developer life of 250,000 sheets, are carried out by duct suction. No limit on the number of copies
We obtained the prospect that toner spill prevention could be achieved almost permanently (marked with ◎).

The reproducibility of isolated dots is as follows: toner particle size 9 μm
The following were good (marked with a circle). In particular, the toner particle size was 6 μm or less, which was excellent (⊚ mark). However, if it is 14 μm or more, reproducibility is poor.

[Third Embodiment] Developing Device FIG. 4 (a) is a front sectional view showing the developing device of the third embodiment, and FIG. 4 (b) is an AA sectional view.

In this developing device 4, the bottom wall 40D of the developing device main body 40 forms a space with a wider gap than the bottom wall 40C at the center at both axial ends of the developing roller 41, and a suction device near the center. 49 is provided.

The suction device 49 includes a suction duct 4 which is connected to an opening 40E formed in the inner side wall of the bottom wall 40D.
9A, a suction fan 49B connected to the end of the suction duct 49A. The air sucked by the suction fan 49B passes through the opening 40E and the suction duct 49A, passes through the dust collecting filter 49C, and is discharged to the outside of the machine.

The bottom wall 40C having a narrow gap facing the outer peripheral surface near both ends in the longitudinal direction of the developing roller 41 has a structure which also serves as the top plate of the suction duct 49A. Also, the developing roller 4
All or a part of the bottom plate portion of the developing device main body 40, 1 of which faces the bottom wall 40C, also serves as the bottom plate of the suction duct 49A.

Experimental machine: Digital copier / printer Si
thios7065 (registered trademark) remodeling machine (see FIG. 1).

Experimental conditions Linear velocity ratio (V _S / V _P ) = 2.0 between the developing roller 41 and the image carrier 1 at the time of image formation. Toner density: 4.5 to 5.2%, recycled toner Is continuously returned to the developing device 4 while the image carrier 1 is rotating. Experimental environment: normal temperature, normal humidity (20 ° C., 50% RH).

A character chart with a 6% printing rate was copied, and image stains were recorded on the image sample with a developer life count of 25.
It was visually confirmed up to 10,000 copies and 500,000 copies.

Toner spills were visually inspected after every 50,000 sheets, and finally, the in-machine stain was visually inspected continuously until the developer life reached 250,000 sheets.

Experimental Results of the Third Embodiment The developing device 4 of the present invention in which a bottom wall 40D having a concave groove and a suction device 49 are provided on the bottom of the developing device main body 40, and a flat (no concave groove) bottom surface. According to the conventional developing device of the wall 40B,
Tables 3 and 4 show the results of comparative examinations regarding toner spills and image stains.

[0059]

[Table 3]

[0060]

[Table 4]

In the case of the conventional developing device in which the bottom wall 40B of the developing device main body 40 is uniform and flat, toner spillage and image contamination occur when a small particle size toner which is disadvantageous in charging rise is used.

In the case of the developing device 4 of the present invention in which the bottom wall 40D in the shape of a groove and the suction device 49 are provided on the bottom of the developing device main body 40, the toner spills because even the small particle size toner is firmly caught and sucked. It was possible to prevent the occurrence of image stains.

Furthermore, by adding suction by the suction device 49, the life of the developer is 5 times twice as long as 250,000 copies.
Toner spills did not occur even after performing a copy of 0,000 sheets, and it was expected that the prevention of toner spills would be achieved almost permanently without the limit of the number of copies.

The reproducibility of the isolated dot is 9 μm in toner particle size.
The following were good. However, if it is 14 μm or more, reproducibility is poor.

[Fourth Embodiment] Developing Device FIG. 5 (a) is a front sectional view of the developing device of the present invention.
(B) is AA sectional drawing.

In the developing device 4, a plurality of openings 49E are formed in the bottom wall 49D below the developing roller 41 of the developing device main body 40.
And the suction device 49 is connected to the opening 49E.

The suction device 49 comprises an opening 49E formed in the bottom wall 49D, a suction duct 49F connected to the opening 49E, and a suction fan 49B connected to the end of the suction duct 49F. The air sucked by the suction fan 49B passes through the opening 49E and the suction duct 49F, passes through the dust collecting filter 49C, and is discharged to the outside of the machine.

In the case of the conventional developing device without the suction device 49 (see FIGS. 3A and 3B), the bottom wall 49
The effects of toner spillage and image stains were compared and examined in the case of the developing device of the present invention including the suction fan 49B connected to the suction duct 49F by forming the opening 49E in D.

Experimental equipment: Digital copier / printer Si
thios7065 (registered trademark) remodeling machine (see FIG. 1).

Experimental conditions: Linear velocity ratio (V _S / V _P ) of the developing roller 41 and the image carrier 1 at the time of image output = 2.0, toner density: 4.5 to 5.2%, toner Particle size: 6 μm, recycled toner is continuously returned to the developing device 4 while the image carrier 1 is rotating, experimental environment: normal temperature, normal humidity (20 ° C., 50% RH), copy of 6% printing character chart The image smear was visually confirmed on the image sample up to the developer life count of 250,000 copies and 500,000 copies.

Toner spills were visually confirmed every 50,000 sheets, and finally, the in-machine stains were visually confirmed and judged intermittently until the life of the developer reached 250,000 sheets.

Experimental Results of Fourth Embodiment Table 5 shows the results of examination of toner spills and image stains depending on whether the suction device 49 is provided in the developing device main body 40.

[0073]

[Table 5]

In the case of the conventional developing device 4 in which the bottom wall 40B of the developing device main body 40 has a flat and uniform gap (see FIG. 3).
(See (a)), toner spillage, and image smear occurred. That is, the loose toner winds from around the bottom wall 40B and gathers and accumulates near the lower ends of the developing roller 41. As copying progresses, the amount of accumulated toner increases and leaks from the lower portion of the developing device 4.

The developing device 4 provided with the suction device 49 of the present invention sucks the free toner and secures it in the suction duct 49F by suction suction, so that the life of the developer is reduced.
It was possible to prevent the occurrence of toner spillage and image stain defects by the time 50,000 copies were made.

[0076]

As is apparent from the above description, the image forming apparatus of the present invention has the following effects.

(1) The transfer residual toner collected by the cleaning device is recycled and returned to the developing device,
In an image forming apparatus that is reused for image formation, toner spillage and image stains are prevented by compensating for rising deterioration of the charge amount of the developer, and isolated dot reproducibility is improved.
An image forming apparatus that achieves high image quality, high production, energy saving, and resource saving is realized.

(2) In particular, when an image forming apparatus capable of high-speed printing is used to process a large amount of printing at a high speed and a large amount of toner is consumed, toner spills, image stains,
It was possible to prevent stains inside the machine and prevent toner spills and image stains from reaching the life of the developer.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus.

FIG. 2 is a cross-sectional view showing an embodiment of an image forming unit arranged around an image carrier.

FIG. 3 is a front sectional view, AA sectional view, and FIG.
Also, a front sectional view and a sectional view taken along the line AA of the developing device according to the first and second embodiments of the present invention.

FIG. 4 is a front sectional view showing a developing device according to a third embodiment of the invention, and an AA sectional view.

FIG. 5 is a front sectional view and an AA sectional view of a developing device according to a fourth embodiment of the invention.

[Explanation of symbols]

4 Developing device 40 Developing device main body 40A Recycled toner supply port 40B, 40C, 40D Bottom wall 40E opening 41 developer carrier (developing roller) 49 Suction device 49A, 49F Suction duct 49B suction fan 49C dust collection filter 49D bottom wall 49E opening A image forming apparatus

Claims (11)

[Claims] 1. An electrostatic latent image formed on an electrostatic latent image carrier is visualized by developing using a developer layer carried on the developer carrier of a developing device, and the visualized image is transferred. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by an apparatus, and a repetitive image is formed, a developing device containing the developer carrier. The shape of the bottom wall below the developer carrying member of the main body is such that the distance between the outer peripheral surface near both ends in the longitudinal direction of the developer carrying member and the bottom wall is the outer circumference near the image forming area of the developer carrying member. An image forming apparatus, wherein the stepped surface is formed to be larger than the distance between the surface and the bottom wall. 2. The image forming apparatus according to claim 1, wherein the developer removed by the cleaning device is returned to the developing device and repeatedly used for image formation. 3. An electrostatic latent image formed on an electrostatic latent image carrier is visualized by using a developer layer carried on the developer carrier of a developing device, and the visualized image is transferred. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by an apparatus, and a repetitive image is formed, a developing device containing the developer carrier. The shape of the bottom wall below the developer carrying member of the main body is such that the distance between the outer peripheral surface near both ends in the longitudinal direction of the developer carrying member and the bottom wall is the outer circumference near the image forming area of the developer carrying member. A stepped surface that is larger than the distance between the surface and the bottom surface wall, and has an opening that connects to the suction duct in the bottom surface wall of the developing device body that faces the outer peripheral surface near both ends in the longitudinal direction of the developer carrying member. Image forming apparatus characterized in that . 4. The image forming apparatus according to claim 3, wherein the developer removed by the cleaning device is returned to the developing device and repeatedly used for image formation. 5. The bottom wall having a narrow gap facing the outer peripheral surface near both ends in the longitudinal direction of the developer carrier and the wide gap facing the outer peripheral surface near the image forming area of the developer carrier. The image forming apparatus according to claim 3, wherein an opening that is connected to the suction duct is provided near a boundary with the bottom wall. 6. The structure according to claim 3, wherein the bottom wall having a narrow gap facing the outer peripheral surface near both ends in the longitudinal direction of the developer carrier has a structure also serving as a top plate of the suction duct. Or the image forming apparatus according to item 5. 7. The structure according to claim 3, wherein all or part of the bottom plate portion of the developing device main body where the developer carrier faces the bottom wall has a structure which doubles as a bottom plate of the suction duct. The image forming apparatus according to any one of 5, 5 and 6. 8. An electrostatic latent image formed on an electrostatic latent image bearing member is visualized by developing using a developer layer carried on the developer bearing member of a developing device, and the visualized image is transferred. In an image forming apparatus in which the transfer residual developer on the electrostatic latent image carrier is removed by a cleaning device after being transferred to a recording sheet by an apparatus, and a repetitive image is formed, a developing device containing the developer carrier. An image forming apparatus, comprising: an opening connected to a suction duct at a bottom portion of the developing device main body from below the developer carrying member of the main body to a tip of the developer carrying member opening. 9. The image forming apparatus according to claim 8, wherein the developer removed by the cleaning device is returned to the developing device and repeatedly used for image formation. 10. The developer according to claim 1, wherein a part or all of the developer is produced by a polymerization method, and the toner has a particle size of 9 μm or less, preferably 8 μm or less. The image forming apparatus according to item 1. 11. The one-component developer according to claim 1, wherein the developer is a two-component developer including a toner and a carrier.
The image forming apparatus according to any one of 0.