JP2001092254A - Image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the faulty carrying of developer and the packing of developer from being caused by the faulty carrying in a developing machine. SOLUTION: An aperture part, forming the path of developer between developer stirring and carrying means provided plurally, is formed so that an interval between a carrying member provided to face to the aperture part, and the aperture part is secured to be 3 mm or larger.

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 for forming an image by an electrophotographic system, and more particularly to a structure of a developing device and a control of toner supply in the image forming apparatus.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus using a two-component developer composed of a toner and a carrier, toner consumed by image formation is replenished so that the toner concentration of the developer is kept constant. It is controlled so that an image with an appropriate density is formed. In addition to this control, the developing device containing the two-component developer is provided with a stirring and conveying means for stirring and conveying the developer, and the stirring and conveying means uniformly mixes the supplied toner with the developer. In addition, the toner concentration of the developer is made uniform and the toner is sufficiently charged. In many cases, the stirring and conveying means is constituted by a plurality of screws for conveying the developer in opposite directions in order to sufficiently stir the developer in a compact developing device.

[0003] To supply toner to the developing device in order to maintain the toner concentration of the developer constant, the toner replenishing device is operated based on the output of a toner concentration sensor for detecting the toner concentration in the developing device. This is done by letting In normal toner supply control, the operation time of the toner supply device is controlled based on the output of the toner density sensor.

Further, the developing device is provided with a scattering prevention device for scattering toner. Toner scattering is a phenomenon in which toner scattered due to agitation or conveyance of a developer leaks out of the developing device and causes contamination in the image forming apparatus. In order to prevent such toner scattering, a scattering prevention device such as a toner suction means is provided at a place outside the developing device where the toner is likely to be scattered.

[0005]

The problem of the conventional stirring and conveying means will be described with reference to FIG. 3 showing a developing device according to an embodiment of the present invention.

[0006] A plurality of screws 4 as stirring and conveying means
Reference numerals 5 and 46 convey the developer in the opposite directions as indicated by white arrows by the respective rotations. Screw 45, 4
6 are provided in transfer chambers 40b and 40c separated by a wall 40a, and the wall 40a has openings 47 at both ends thereof.
A and 47B are provided. The developer is screw 45, 4
6 by the rotation of the stirring and conveying members 45B and 46B, as shown by the white arrows, and the openings 47A and 4B.
At 7B, one screw moves to the other screw. In order to ensure the movement of the developer in the openings 47A and 47B, paddles 45C and 46C as auxiliary conveyance members are respectively attached to the screws 45 and 46, respectively.
It is provided facing the openings 47A and 47B.

[0007] The developer is supplied to a screw 45,
Due to the meandering, the toner is conveyed while being agitated and agitated, and the toner and the carrier are mixed and the toner is charged efficiently in the narrow developing device.

[0008] However, it has been found that the following problems have been encountered in the developer stirring and conveying means as described above.

Since the developer carrying force at the openings 47A and 47B is relatively weaker than the carrying force at the screw blades 45B and 46B (stirring / conveying member), the developer stays at these openings. However, there is a case where a conveyance failure such as a packing state occurs. Such a conveyance failure causes various obstacles in image formation. For example, the sensitivity of the toner density sensor provided in the vicinity of the opening changes, and the toner density fluctuates. As a result, an image defect occurs.

An object of the present invention is to solve such a problem in the conventional stirring and conveying means.

In the conventional toner supply control, as described above, the time for replenishing a fixed amount of toner is controlled based on the output of the toner density sensor. In the case of forming an image having a high rate and a large amount of toner consumption, there is a problem that the toner supply cannot follow the consumption and the image density is reduced.

Another object of the present invention is to solve the above-described problem of the decrease in image density in the conventional toner supply.

Further, in the conventional developing device, as described above, since the toner scattered outside the developing device is sucked, the toner scattered outside the developing device cannot be sufficiently collected. This causes the inside of the image forming apparatus to become dirty.

Still another object of the present invention is to improve a countermeasure against in-machine contamination of an image forming apparatus, which has been insufficient in the past.

[0015]

The object of the present invention is as follows.
The present invention is achieved by any of the following inventions.

(1) Developing means for transporting the developer to the development area and developing the electrostatic latent image, a plurality of agitating and transporting members for agitating and transporting the developer, and A developing device having a plurality of agitating and conveying means having an auxiliary conveying member for assisting the conveying, and an opening for forming a developer passage between the plurality of agitating and conveying means, and a wall separating the plurality of agitating and conveying means; In the image forming apparatus, the auxiliary transporting member is provided facing the opening, and the opening is formed such that a distance of 3 mm or more is formed between the auxiliary transporting member and an edge of the opening. An image forming apparatus comprising:

(2) The image forming apparatus according to (1), wherein a toner concentration sensor for detecting a toner concentration of the developer is provided near the opening.

(3) A toner density sensor for detecting the toner density of the developer in the developing device, a toner replenishing device for replenishing the developing device with toner, and a toner replenishing ratio for the toner replenishment by the toner replenishing device. An image forming apparatus provided with a toner replenishing device having control means for performing control based on the output of the toner replenishing device, when the toner concentration does not recover even after replenishing the toner by the toner replenishing means, An image forming apparatus that performs control to reduce a process speed.

(4) Developing means for transporting the developer to the developing area to develop the electrostatic latent image, forming a suction port facing the developing means passing through the developing area, and a suction path following the suction port. An image forming apparatus comprising: a suction box; a filter provided in the suction box; and a developing device having a suction unit for sucking air through the suction port and the filter.

(5) A magnet device having a plurality of magnetic poles and fixedly arranged inside the developing means, wherein the suction port is
The image forming apparatus according to (4), wherein in the flow of the developer on the developing unit, the magnet device is formed downstream of the developing region and upstream of a portion that forms a repulsive magnetic field. .

(6) The image forming apparatus according to the above (5), wherein the developing means, the suction box, and the filter are provided as a unit so as to be detachable from the image forming apparatus.

[0022]

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention.

The original is placed on the original feeder table 1 of the automatic original feeder 1.
1 with the image surface facing upward, and a delivery roller 1
The sheet is sent out one by one by the operation of the registration roller 1
After the document is temporarily stopped by 3 and the leading end is adjusted, the document is conveyed to the conveyance drum 14, and the image reading unit 2 reads the image surface while the document is integrally rotated counterclockwise along the surface of the conveyance drum 14. After that, the sheet is branched from the drum surface at a position substantially halfway around and is discharged to the sheet discharge table 15. The automatic document feeder 1 has a transport function for double-sided reading in addition to the transport function for single-sided reading, but this operation is omitted.

In the image reading section 2, a first mirror unit 23 having a light source 23a and a mirror 23b sequentially illuminates and reads passing documents at a position immediately below the transport drum 14 so as to be orthogonal to the moving direction of the documents. The second mirror unit 24 including the arranged mirrors 24a and 24b
And forms an image on a linear imaging element 26 via an imaging lens 25 to become image information. Further, the image reading section 2 places the original on the stationary original platen 27, and the mirror unit 23,
24 also has the function of moving and reading.

The image information of the document read by the image reading section 2 is subjected to image processing by image processing means and is temporarily stored in a memory as image information.

When the image forming section 3 operates, the image information is read from the memory and input to the image writing section 33,
A laser beam modulated according to image information from a laser light source (not shown) performs main scanning exposure by rotating a polygon mirror. Then, main scanning exposure in the axial direction of the photoconductor drum 31 and sub-scanning by rotation of the photoconductor drum 31 are performed on the photoconductor drum 31 to which a charging potential has been previously applied by the charging device 32, and the photoconductor drum 31 receives image information based on image information. An electrostatic latent image is formed. The electrostatic latent image is reversely developed by the developing device 40 to be a toner image. This developer is, for example, a two-component developer obtained by mixing a carrier composed of magnetic powder having an average particle diameter of about 15 to 50 μm and a toner composed of colored particles having an average particle diameter of about 3 to 9 μm. A layer of about 0.1 to 1.0 mm is formed thereon and developed to form a toner image. In parallel with the formation of the toner image on the photosensitive drum 31, recording paper is fed from the manual paper feed unit 19 or the paper feed tray 7 containing the recording paper. The paper feed tray 7 has, for example, three stages of 7a, 7b, and 7c, and one of the paper feed rollers 51A, 51B, and 51C is operated to carry out the recording paper, and the paper is fed to the transport rollers 55 and 56 and the timing roller 39. The sheet is fed and fed to the photosensitive drum 31 in synchronization with the toner image on the photosensitive drum 31.

The toner image on the photosensitive drum 31 is transferred to the transfer device 3
The recording paper carrying the toner image is transferred and transferred to the recording paper to which the charge of the opposite polarity to the toner has been applied by 5, and the recording paper carrying the toner image is discharged by the discharger 36 to be separated from the photosensitive drum 31, and the transport belt is moved. After being conveyed to the fixing device 38 and subjected to a fixing process by heating and pressing, the sheet is discharged from the fixing discharge roller 61 of the discharge section 6 and discharged to the discharge tray 64.

On the other hand, the photosensitive drum 31 from which the recording paper is separated
After the residual potential is removed, the residual toner is removed and cleaned by the cleaning device 37.

FIG. 2 is an enlarged vertical sectional view of the developing device 40 of FIG. 1, FIG. 3 is a horizontal sectional view of the developing device, and FIG. 4 is a partially enlarged view of an end portion of the screw. FIG. 5 is a perspective view of the developing device showing the rotating member.

In FIG. 2, a developing sleeve 41 as a developing means rotates as shown by an arrow, and
The developer is transported to a developing area DS formed between the photosensitive drum 31 and the photosensitive drum 31. A fixed magnet 42 as a magnet device for generating a magnetic field is provided inside the developing sleeve 41. The magnetic poles of the magnet 42 are, for example, S1, S2, S3.
And five poles of N1 and N2. The same magnetic pole S adjacent to each other
1 and S2 form a repulsive magnetic field to peel off the developer D after the developing process on the developing sleeve 41,
Delete the above image history. The thickness of the developer D supplied on the peripheral surface of the developing sleeve 41 is regulated to a predetermined amount by the developer regulating plate 43, and is conveyed to the developing area DS. The developer D, which has developed the electrostatic latent image on the photosensitive drum 31 in the developing area DS, is peeled off from the developing sleeve 41 by a repulsive magnetic field generated by the stripping magnetic poles S1 and S2, and is conveyed by an impeller 44 described later. The first and second screws 45 and 46 as agitating / conveying means make the toner replenishing unit 8
The toner T supplied from 0 is added and stirred.

Next to the developing sleeve 41, there is an impeller 44 for stirring and supplying the developer. The impeller 44 has a rotating shaft 4
4A and a plurality of blades 44B extending in parallel with the rotation axis, next to which are a first screw 45 as a stirring / transporting means for stirring the developer and a second screw as a stirring / transporting means via a wall 40a. A screw 46 is provided. The first screw 45 includes a rotating shaft portion 45A connected to a driving source, a spiral wing portion 45B as a stirring and carrying member for carrying the developer in the rotating shaft direction while stirring the developer, and an auxiliary carrying member provided at an end portion. And a paddle 45C. Similarly,
The second screw 46 is a rotating shaft 46A connected to a driving source.
And a spiral wing portion 46B as a stirring and conveying member for conveying the developer in the rotation axis direction while stirring, and a paddle 46C as an auxiliary conveying member for assisting the stirring and conveying. The paddles 45C and 46C are composed of a plurality of plates provided at the ends of the rotating shaft portions 45A and 46A in parallel with the shafts.
The paddle 46C transports the developer D from the second screw 46 to the first screw 45, respectively.

The arrows in FIGS. 2 and 4 indicate the developing sleeve 41, impeller 44, and two screws 45, 46, which are the respective rotating members.
, And the white arrow in FIG. 3 indicates the moving direction of the developer. As shown in FIGS. 3 and 4, these rotations are transmitted from a driving source (not shown) to the screws 45 and 46, and are performed.

The first screw 45 is disposed adjacent to the impeller 44, collects and transports the developer after the development, and supplies a new developer to the impeller 44. The second screw 46 is disposed with the wall 40a separated from the first screw 45. The end of the first screw 45 is provided with a paddle 45C and an opening 47A in a wall near the paddle 45C.
The developer D is conveyed to the second screw 46 while being stirred from 7A. Similarly, paddle 4 is also provided at the end of second screw 46.
There is an opening 47B in the wall near 6C, and the developer D is conveyed to the first screw 45 while being stirred. At the bottom near the opening 47A of the first screw, a toner density sensor Z for detecting the toner density of the developer D by measuring the magnetic permeability is provided. The toner density sensor Z is a commercially available toner density sensor that detects toner density by detecting a change in the magnetism of a developer in a two-component developer composed of a magnetic carrier and a toner depending on the toner density.

As described above, the first screw 45 and the second screw 46 are connected to the first transfer chamber 4 formed on both sides of the partition wall 40a standing upright from the bottom of the developing device 40.
0b and the second transfer chamber 40c, respectively, and are rotated in opposite directions, so that the developer D is transferred in the opposite direction. The upper portions of the transfer chambers 40b and 40c are closed with a top plate 48. A toner receiving port 40f is provided at one corner of the upper top plate 48 of the second transfer chamber 40c to receive the replenished toner T. A toner replenishing unit 80 is disposed above the toner replenishing unit 80. The toner T in the toner replenishing unit 80 is, for example, based on the detection result of the toner density sensor Z,
Toner supply roller 80 rotating in toner supply port 80b
The toner T is electrostatically attached to the toner supply port 80b, is scraped off by a brush member provided at the rotation downstream of the toner supply roller 80a of the toner supply port 80b, and transfers the toner T to the second transfer chamber 40c through the toner receiving port 40f. Replenished. Since the toner adheres to the toner replenishing roller 80a to a substantially constant thickness, the amount of the replenished toner is accurately controlled by the rotation amount of the toner replenishing roller 80a. When the toner supply container (hopper) 81 is mounted on the image forming apparatus, the toner supply port 81a is connected to the toner supply section 80, and the toner supply port 81a is opened.

As shown in FIG. 2, the developing device 40 has an air suction port 49C and a suction path 4 connected to the suction port 49C.
A suction box 49D forming 9A is provided. The suction passage 49A
Is provided with a filter F, and a suction unit (not shown) is connected to the exhaust port 49B of the suction box 49D. The suction box 49D is formed integrally with the developing device 40,
Is detached from the image forming apparatus as a unit. The suction port 49C faces the developing sleeve 41 downstream of the developing region DS and upstream of the repulsive magnetic field formed by the magnetic poles N2 and N3 in the flow of the developer when the developer is transported by the developing sleeve 41. Formed. With the arrangement of the suction ports 49C, it is possible to effectively prevent the toner from scattering outside the developing device 40.

The structure of the developing device 40 and the toner supply operation have been described above. As described above, the wall 40a exists between the first and second screws 45 and 46, but the paddle 45C is provided at both ends. , 46C, the toner moves between the screws through openings 47A and 47B which are opened to a degree slightly larger than the width of the screws. When the first and second screws 45 and 46 transport the developer D in the axial direction of the screw and transport it to the end of the screw, the transport force in the axial direction disappears, and the transport force for the developer D weakens and the developer stays. Resulting in.
For this reason, if the delivery of the developer between the screws is insufficient, the developer D sent later may be in a packing state. This state affects the toner density sensor Z, making it impossible to detect a correct density. Therefore, as shown in FIG. 4, the length from the side plate Q to the paddle end which is the paddle width is J, and the length from the side plate Q to the end of the wall of the opening 47A is K, and L = K−J ≧ The opening 47A is widened to 3 mm. That is, the edge of the opening 47A and the paddle 45
C so that the distance L between the opening 47
Form A. Note that the upper limit of the interval L is set under this condition because it is not desirable to widen the opening 47A beyond the installation position of the toner density sensor Z. This is because the detection value of the toner density sensor Z is not affected.

The opening 47B is formed similarly to the opening 47A in relation to the paddle 46C.

The openings 47A and 47B are connected to paddles 45C,
By forming the developer D wider by 3 mm or more from the end of 46C, the developer D is smoothly transported through the openings 47A and 47B, and stagnation and packing are eliminated. as a result,
Undesirable phenomena such as a change in the sensitivity of the toner density sensor Z installed near the opening 47A are prevented.

Next, control of toner supply will be described.

The toner density sensor Z has a density boundary value of, for example, 2.0 V, and the output voltage R of the toner density sensor Z is R ≦ R.
If 2.0V, the toner concentration is determined to be sufficiently high and toner replenishment is not performed. However, if R> 2.0V, the toner concentration is determined to have decreased, and the toner replenishing roller 80a as a toner replenishing unit is driven to release toner. The toner is supplied from the supply unit 80. For example, when the output voltage R of the toner density sensor Z is 2.1V, 2.2V, 2.3V, 2.4V,.
As the voltage increases by 5 V and 0.1 V, the control is performed stepwise in five steps corresponding to the voltage changes in five steps. That is, the toner supply time is controlled by the CPU as control means so that the toner supply time becomes longer as the toner concentration becomes lower.

FIG. 6 shows a cycle of the toner supply control in this embodiment. In FIG. 6, the horizontal axis indicates the time of toner replenishment, and toner replenishment is performed with H0, for example, 2 seconds as one cycle. Of the replenishment cycle H0, the first h1,
For example, the density detection by the toner density sensor Z is performed in 0.1 seconds, and the subsequent time h is allocated to toner supply. The time h is, for example, 5 based on the output of the toner density sensor Z.
At this stage, the toner supply roller 80a operates to supply the toner T. FIG. 6 shows the toner replenishing roller 80 within the time h.
An operation time during which a operates, that is, an example h2 of a replenishment time is shown. The supply time h2 is, for example, 0.3, 0.7, 1.1, 1.5,
The toner supply time is selected from five steps of 1.9 seconds. In the present embodiment, the number of toner supply cycles shown in FIG. 6 is determined based on the output of toner density sensor Z, and the toner supply time h2 per cycle is determined based on the output of toner density sensor Z. Controlled. As a result, the control range of toner replenishment becomes extremely wide, and it is possible to cope with a wide range of density changes of an image to be developed. Therefore, even when the development of an image having a high blackening ratio is continued, the toner density does not decrease.

In the present embodiment, a measure is taken to reduce the image forming speed in order to prevent a decrease in image density in the development of an image having a high blackening rate. That is, when the toner density sensor Z detects that the toner density has decreased in image formation, the toner consumption rate is reduced by reducing the image forming speed, thereby preventing the image density from decreasing.

The control for lowering the image forming speed is performed by changing the interval between the recording sheets while keeping the speed of the image forming process, that is, the rotation speed of the photosensitive drum 31 and the conveying speed of the recording sheets constant. It is desirable to control the number of images to be formed per time. By changing the image forming speed while keeping the toner replenishment constant, the ratio of the amount of the replenished toner to the amount of the toner consumed by the image formation is increased, so that the lowered toner density can be recovered. Of course, as the control for changing the image forming speed, it is also possible to perform control for changing the speed of the image forming process, that is, the conveying speed of the photosensitive drum 31 and the recording paper.

FIG. 7 is a flowchart of the control for lowering the image forming speed.

In the flowchart of FIG. 7, first, at 100, density information is output from the toner density sensor, and at 101, it is determined whether the toner density is high or low. If thin, 1
In step 02, toner supply is started. The toner replenishment at 102 is a replenishment under the control of controlling the number of replenishment cycles and the replenishment time per one cycle based on the output of the toner density sensor Z as described above. Further, the process proceeds to 103 to determine whether the replenishment time is the maximum (1.9 seconds). 103
If the replenishment time is within the maximum value, the toner density detection 100
If it exceeds the maximum, the process proceeds to step 106, where it is determined whether the toner density has been restored to an appropriate density value. If it has recovered, the process returns to the toner density detection 100, but if it has not recovered, toner supply is continued, and the image forming speed is reduced at 107 to form an image. In the image formation performed with the image forming speed reduced in this way, the toner forming speed is reduced with respect to the toner replenishment performed under the same control as before the image forming speed is reduced. On the other hand, the toner consumption rate decreases, and as a result, the toner concentration of the developer in the developing device increases, and the decrease in the toner concentration recovers.

In step 107, the image forming speed may be reduced to the initial value of 100 in a state where the image formation is performed (YES in 104). Therefore, when the toner density is recovered (NO in 101). Then, a step (105) of restoring the reduced image forming speed to the original speed is executed. As described above, even if toner supply is performed with the toner supply time being maximized, if there is a decrease in the toner density, the image formation speed is controlled to prevent the image density from decreasing, and the image having the appropriate density is controlled. Is formed.

Next, toner collection by suction in the image forming apparatus will be described with reference to FIG.

As described above, the developing sleeve 41 shown in FIG.
A suction port 49C is provided opposite to the suction port, a suction path 49A is provided following the suction port C, a suction means (not shown) is connected, and the suction is performed by the suction means to bring the inside of the developing device 40 into a negative pressure state. In addition, the developer causing the stain is sucked, and the toner is not scattered from the developing device 40 to the outside of the device. The installation position of the suction port 49C is downstream of the development region DS in the flow of the developer on the development sleeve 41, and the portion of the repulsive magnetic field that peels off the developer that has contributed to the development from the development sleeve 41, ie, the magnetic poles S1 and S2. A position that is upstream with respect to the portion in between is desirable. The suction box 4 that forms the suction port 49C and the suction path 49A and houses the filter F
9D is formed integrally with the developing device 40 at the bottom of the developing device 40 so that the suction box 49D can be replaced at the same time when the unit of the developing device 40 is replaced, so that the unit of the developing device 40 is simple and always clean. Is configured.

[0049]

According to the first aspect of the present invention, the poor conveyance of the developer in the developing device is eliminated, and a good image is always formed.

According to the second aspect of the present invention, the uneven toner concentration of the developer at the position where the toner concentration sensor is provided is eliminated, and the accurate toner concentration is always detected.
As a result, a good image is always formed.

According to the third aspect of the present invention, even when images having a high blackening ratio are continuously formed, the toner density is kept constant and a good image is always formed.

According to the fourth aspect of the present invention, leakage of toner from the developing device is extremely effectively prevented, and contamination in the image forming apparatus is prevented.

According to the fifth aspect of the present invention, toner leakage from the developing device is particularly well prevented.

According to the sixth aspect of the present invention, when the developing device is attached / detached, the toner collecting portion is also integrally attached / detached, so that the toner collecting portion is cleaned, the filter of the toner collecting portion is replaced, or the toner collecting portion is replaced. It is easy to exchange and so on.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention.

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

FIG. 3 is a horizontal sectional view of the developing device according to the embodiment of the present invention.

FIG. 4 is a partially enlarged view of the developing device according to the embodiment of the present invention.

FIG. 5 is a perspective view of a developing device according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating a toner supply cycle according to the embodiment of the present invention.

FIG. 7 is a flowchart of a toner supply cycle control according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Automatic document feeder 2 Image reading unit 3 Image forming unit 6 Discharge unit 7 Paper feed tray 40 Developing device 40 f Toner receiving port 41 Developing sleeve 44 Impeller 45 First screw 46 Second screw 45C, 46C Paddle 47A, 47B Opening 49A Suction path 49B Exhaust port 49C Suction port 49D Suction box 80 Toner supply unit 81 Toner supply container CPU control means F Suction filter Z Toner density sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/00 384 G03G 21/00 538 538 15/08 507E F-term (Reference) 2H027 DD05 DD07 DE04 DE10 EA04 EA06 EC06 EC09 ED02 ED08 ED16 ED17 EE02 EE03 EE04 EF09 JA03 JB03 JC06 ZA10 2H031 AA01 AA12 AA17 AB02 AB03 AC02 AC39 BA04 BC03 2H077 AA12 AA15 AB02 AB13 AB14 AB15 AC03 AD06 AD13 DB08 DA12 DA13

Claims (6)

[Claims] A developing means for conveying the developer to a developing area to develop an electrostatic latent image; a plurality of stirring and conveying members for stirring and conveying the developer; and a conveyance of the developer by the plurality of stirring and conveying members. A plurality of agitating and conveying means having an auxiliary conveying member for assisting the developing, and a developing device having an opening for forming a passage for the developer between the plurality of agitating and conveying means and having a wall separating the plurality of agitating and conveying means. In the image forming apparatus, the auxiliary transport member is provided facing the opening, and 3 m is provided between the auxiliary transport member and an edge of the opening.
An image forming apparatus, wherein the opening is formed so as to have an interval of at least m. 2. The image forming apparatus according to claim 1, wherein a toner density sensor for detecting a toner density of the developer is provided near the opening. 3. A toner density sensor for detecting a toner density of a developer in the developing device, a toner replenishing unit for replenishing toner to the developing device, and a toner replenishment ratio by the toner replenishing unit. An image forming apparatus comprising a toner replenishing device having control means for controlling based on an output, the control means comprising: An image forming apparatus that performs control to reduce the speed. 4. A developing means for transporting a developer to a developing area to develop an electrostatic latent image, a suction port facing the developing means passing through the developing area, and a suction path forming a suction path following the suction port. An image forming apparatus comprising: a box; a filter provided in the suction box; and a developing device having a suction unit for sucking air through the suction port and the filter. 5. A magnetic device having a plurality of magnetic poles and fixedly disposed inside the developing means, wherein the suction port is provided downstream of the developing area in a flow of the developer on the developing means. The image forming apparatus according to claim 4, wherein the magnet device is formed upstream of a portion that forms a repulsive magnetic field. 6. The image forming apparatus according to claim 5, wherein the developing unit, the suction box, and the filter are detachably provided as a unit in the image forming apparatus.