JP2000089559A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain an excellent image by preventing metallic powder produced in the inside of an image forming device from entering the inside of a developing unit and preventing an image defect from being caused. SOLUTION: This image forming device is provided with an image carrier 1 whose image carrying surface is moved and a developing container 73 having a developer carrier facing the carrier 1 and carrying developer so as to develop the image at the moving image carrying surface and holding the developer supplied to the carrier 1. Besides a member 100 having magnetic force is proximately arranged at a more upstream side where the image carrying surface is moved than the position of the container 73 where the developer carrier and the carrier 1 are opposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a developer carrier for carrying a developer for developing an image on an image carrier and a developing container for holding a developer to be supplied to the image carrier. Related to an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, as an example of an image forming apparatus provided with an image carrier, a developer carrier and a developing container, as shown in FIG. 6, an electrostatic latent image is formed on an image carrier composed of a photoreceptor. An electrophotographic color image forming apparatus has been proposed in which a full-color image is formed by developing this electrostatic latent image and transferring it to a recording material.

In an image reading section, the original 30 is placed on an original platen glass 31 and is exposed and scanned by an exposure lamp 32, so that a reflected light image from the original 30 is reflected on a mirror 33.
The light is condensed on a full-color sensor 35 by a, 33b, 33c and a lens 34 to obtain a color separation image signal. The color-separated image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown) and sent to an image forming unit.

At this time, in the image forming section, the photosensitive drum 1 as an image carrier is connected to a drum shaft 37 as holding means, and is driven to rotate in a direction indicated by an arrow by a driving means (not shown). A pre-exposure lamp 1 is provided around the photosensitive drum 1.
1, a corona charger 2, a laser exposure optical system 3, which is an exposure means, a potential sensor 12, and four developing devices 4y and 4 having different colors.
c, 4m, 4Bk, the on-drum light amount detecting means 13, the transfer device 5, and the cleaning device 6 are arranged.

In the laser exposure optical system 3, an image signal from an image reading unit is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by a rotary polygon mirror 3a, and the lens 3b The light is projected on the cylindrical surface of the photosensitive drum 1 through the mirror 3c.

At the time of image formation, the photosensitive drum 1 is rotated in the direction of the arrow, and the photosensitive drum 1 after having been neutralized by the pre-exposure lamp 11 is uniformly charged by the corona charger 2 so that the light image E To form an electrostatic latent image.

Next, a predetermined developing device is operated to develop the latent image on the photosensitive drum 1 to form a toner image on the photosensitive drum 1 using a resin as a base. The developing device has an eccentric cam 24.
The operations of y, 24c, 24m, and 24Bk make it possible to selectively approach the photosensitive drum 1 in accordance with each separation color.

Further, the toner image on the photosensitive drum 1 is
The image is transferred from a recording material cassette 7 to a recording material supplied to a position facing the photosensitive drum 1 via a transport system and a transfer drum 5. The transfer drum 5 includes a transfer charger 5b, an attraction charger 5c for electrostatically attracting a recording material, and an inner static elimination charger 5d, all of which are in urging contact with the photosensitive drum 1. The transfer drum 5 on which the recording material is electrostatically attracted transfers the toner image on the photosensitive drum 1 onto the recording material by the transfer charger 5b according to the rotation.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the transfer drum 5 to form a full-color image.

In the case of forming a full-color image, when the transfer of the four color toner images is completed in this manner, the recording material is separated from the separation claw 8.
a, the sheet is separated from the transfer drum 5 by the action of the separation push-up roller 8b, and is discharged to the tray 10 via the heat roller fixing device 9.

As shown in FIG. 7, the developing device has a partition wall 7 inside.
0, a developing container 73 partitioned by a stirring chamber 71 and a developing chamber 72
In the stirring chamber 71 and the developing chamber 72, developer conveying screws 74 and 75 are rotatably provided, respectively. The developer transport screw 74 in the stirring chamber 71 is driven to rotate by a drive system (not shown),
3 is conveyed while being stirred with the non-magnetic toner supplied into the stirring chamber 71 from a toner supply port (not shown) provided on the front side of the developing container 73, and the developer is opened at the end of the partition 70. To the developing chamber 72.

On the other hand, a developer conveying screw 75 in the developing chamber 72 is driven to rotate by a drive system (not shown),
The developer transferred from 1 into the developing chamber 72 is transported in the opposite direction, and the developer is returned into the stirring chamber 71 through the opening at the opposite end of the partition 70. A developing sleeve 77 serving as a developer carrier is provided in an upper opening 76 in the developing chamber 72.
Are rotatably supported by the developing container 73, and are disposed to face the photosensitive drum 1 serving as an image carrier. The developing sleeve 77 is driven to rotate with respect to the rotating photosensitive drum 1 in the direction of the arrow in the drawing, and draws up the developer conveyed by the developer conveying screw 75 in the developing chamber 72. The developer is regulated by a blade 78 close to the developing sleeve 77 to form a developer layer having a predetermined thickness. Then, the developer layer is applied to the developing sleeve 77.
With the rotation of the photosensitive drum 1, the toner is conveyed to a portion facing the photosensitive drum 1 so that toner adheres to the electrostatic latent image formed on the surface of the photosensitive drum 1, and the electrostatic latent image is visualized as a toner image.

A voltage is applied to the developing sleeve 77 from a power supply unit (not shown) for the purpose of improving contrast or preventing fogging of a bright portion.

[0014]

However, the following problems may occur in the conventional image forming apparatus.

That is, there are many metal parts in the image forming apparatus, and the metal parts may come into sliding contact with each other at the time of assembling, operation, service maintenance, and the like to generate metal powder. When one of these metal powders, which greatly exceeds the particle size of the developer, adheres to the surface of the developer carrier, as shown in FIG. 8, the surface of the image carrier and the developer carrier to which a voltage is applied are separated. It may cause bridging and cause a local and fine leak phenomenon. This minute leak may cause a small ring-shaped black spot image defect on the image.

Further, when metal powder that does not directly adhere to the developer carrying member enters the developing container, it is conveyed together with the developer through the developing container, and is eventually pumped up by the developer carrying member, and the same result as described above is obtained. Becomes

An object of the invention according to the present application is to provide an image forming apparatus capable of preventing an image defect due to a metal powder entering a developing device and maintaining a good image for a long time.

[0018]

As a first configuration for realizing the object of the invention according to the present application, an image carrier whose image carrier surface moves, and an image carrier that moves opposite to the image carrier. An image forming apparatus comprising: a developer container for supporting a developer so as to develop an image on a support surface; and a developing container holding a developer to be supplied to the image carrier. A member having a magnetic force is arranged close to the upstream side where the image bearing surface moves from the position of the developing container facing the body.

According to the above-described structure, metal powder generated inside the image forming apparatus, in particular, one approaching the developing device along the surface of the image carrier can be collected beforehand, and the metal powder to the developing device can be collected. It is possible to prevent an image defect due to the entry and maintain a good image for a long time.

As a second configuration for realizing the object of the invention according to the present application, the member having the magnetic force is provided so as to be movable between an approach position and a retracted position with respect to the image carrier. It is characterized by the following.

According to the above arrangement, when the image forming apparatus is not operating, the member having magnetic force can be brought closer to the surface of the image carrier, and more reliable collection of metal powder can be realized. Can be.

According to a third configuration for realizing the object of the present invention, the member having a magnetic force is a magnet plate member or a magnet roller provided integrally with the developing container. I do.

According to the above-described structure, more reliable collection of metal powder can be realized at a stable position with respect to the developing container by using a magnetic member such as a magnet plate member or a magnet roller.

As a fourth configuration for realizing the object of the invention according to the present application, an image carrier having an image bearing surface that moves and an image is developed on the image carrier surface that moves and faces the image carrier. An image forming apparatus having a developer carrier for carrying a developer to carry the developer and a developing container for holding the developer to be supplied to the image carrier; A member having a magnetic force is arranged close to at least one of the possible paths.

According to the above configuration, metal powder generated during service or the like can be collected.

According to a fifth aspect of the invention for realizing the object of the present invention, the member having a magnetic force is provided at at least one position on a path through which foreign matter can fall toward the developer carrier or the developing container. It is characterized by having been done.

According to the above configuration, it is possible to prevent the metal powder generated in a state where the image forming apparatus is not operating at the time of maintenance or the like from directly dropping into the developer carrier or the developing container.

A sixth configuration for realizing the object of the invention according to the present application is as follows. A toner supply having a path for supplying a non-magnetic toner to a developing container holding a developer to be supplied to an image carrier is provided. In the developing device having the means, a member having a magnetic force is provided in at least one portion of the toner supply path of the toner supply means.

According to the above-described configuration, even if the metal powder enters the hopper or the like and is conveyed together with the non-magnetic toner into the developing container, the metal powder is collected before entering the developing container. This can prevent image defects and maintain a good image for a long time.

According to a seventh aspect of the present invention, there is provided an image forming apparatus having a developing device according to the present invention.

According to the above configuration, it is possible to provide an image forming apparatus capable of preventing an image defect and maintaining a good image for a long time.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described. FIG. 6 is a schematic configuration diagram of an electrophotographic color image forming apparatus according to the present embodiment.

In the image reading section, the original 30 is placed on an original platen glass 31 and exposed and scanned by an exposure lamp 32 so that a reflected light image from the original 30 is reflected on a mirror 33.
The light is condensed on a full-color sensor 35 by a, 33b, 33c and a lens 34 to obtain a color-separated image signal. The color-separated image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown) and sent to an image forming unit.

At this time, in the image forming section, the photosensitive drum 1 as an image carrier is connected to a drum shaft 37 as holding means, and is driven to rotate in a direction indicated by an arrow by a driving means (not shown).

Around the photosensitive drum 1, a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system 3 as exposure means, a potential sensor 12, and four developing devices 4 of different colors.
y, 4c, 4m, 4Bk, on-drum light amount detecting means 13,
A transfer drum 5 as a transfer device and a cleaning device 6 are arranged.

In the laser exposure optical system 3, an image signal from the image reading unit is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by the rotary polygon mirror 3a, and the lens 3b The light is projected on the cylindrical surface of the photosensitive drum 1 through the mirror 3c.

At the time of image formation, the photosensitive drum 1 is rotated in the direction of the arrow, and the photosensitive drum 1 after having been neutralized by the pre-exposure lamp 11 is uniformly charged by the corona charger 2 so that the light image E To form an electrostatic latent image.

Next, a predetermined developing device is operated to develop the latent image on the photosensitive drum 1 to form a toner image on the photosensitive drum 1 using a resin as a base. The developing device has an eccentric cam 24.
The operations of y, 24c, 24m, and 24Bk make it possible to selectively approach the photosensitive drum 1 in accordance with each separation color.

Further, the toner image on the photosensitive drum 1 is
The image is transferred from a recording material cassette 7 to a recording material supplied to a position facing the photosensitive drum 1 via a transport system and a transfer drum 5. The transfer drum 5 includes a transfer charger 5b, an attraction charger 5c for electrostatically attracting a recording material, and an inner static elimination charger 5d, all of which are in urging contact with the photosensitive drum 1. The transfer drum 5 on which the recording material is electrostatically attracted transfers the toner image on the photosensitive drum 1 onto the recording material by the transfer charger 5b according to the rotation.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the transfer drum 5 to form a full-color image.

In the case of forming a full-color image, when the transfer of the four color toner images is completed in this manner, the recording material is separated from the separation claw 8.
a, the sheet is separated from the transfer drum 5 by the action of the separation push-up roller 8b, and is discharged to the tray 10 via the heat roller fixing device 9.

After the transfer of the toner image to the photosensitive drum 1, the cleaning device 6 cleans the toner remaining without being transferred, that is, the residual toner, and is supplied to the image forming apparatus again.

As shown in FIG. 7, the developing device has a partition 7 inside.
0, a developing container 73 partitioned by a stirring chamber 71 and a developing chamber 72
In the stirring chamber 71 and the developing chamber 72, developer conveying screws 74 and 75 are rotatably provided, respectively. The developer transport screw 74 in the stirring chamber 71 is driven to rotate by a drive system (not shown),
3 is conveyed while being stirred with the non-magnetic toner supplied into the stirring chamber 71 from a toner supply port (not shown) provided on the front side of the developing container 73, and the developer is opened at the end of the partition 70. To the developing chamber 72.

On the other hand, the developer conveying screw 75 in the developing chamber 72 is driven to rotate by a drive system (not shown),
The developer transferred from 1 into the developing chamber 72 is transported in the opposite direction, and the developer is returned into the stirring chamber 71 through the opening at the opposite end of the partition 70. A developing sleeve 77 serving as a developer carrier is provided in an upper opening 76 in the developing chamber 72.
Are rotatably supported by the developing container 73, and are disposed to face the photosensitive drum 1 serving as an image carrier. The developing sleeve 77 is driven to rotate with respect to the rotating photosensitive drum 1 in the direction of the arrow in the drawing, and draws up the developer conveyed by the developer conveying screw 75 in the developing chamber 72. The developer is regulated by a blade 78 close to the developing sleeve 77 to form a developer layer having a predetermined thickness. Then, the developer layer is applied to the developing sleeve 77.
With the rotation of the photosensitive drum 1, the toner is conveyed to a portion facing the photosensitive drum 1 so that toner adheres to the electrostatic latent image formed on the surface of the photosensitive drum 1, and the electrostatic latent image is visualized as a toner image.

A voltage is applied to the developing sleeve 77 from a power supply unit (not shown) for the purpose of improving the contrast or preventing the light portion from being fogged.

On the upstream side in the moving direction of the surface of the photosensitive drum 1 of the developing sleeve 77, a magnet plate member 100 such as a magnet is provided as a member having a magnetic force.
Are supported by the developing container 77 so as to maintain a predetermined interval on the surface of the photosensitive drum 1 over the entire area in the longitudinal direction of the photosensitive drum 1.

With this configuration, the metal powder-like foreign matter which is generated in the image forming apparatus and adheres to the image carrier or approaches the surface of the image carrier, as shown in FIG. The magnetic force of the magnet plate member 100 causes the magnet plate member 100 to collect the toner, thereby preventing the adhesion to the developing sleeve 77 as a developer carrier and the entry of foreign matter into the developing container 73.

As described above, in the image forming apparatus according to the present embodiment, the metal powder-like foreign matter generated during the assembly of the image forming apparatus, the operation of the image forming apparatus, the maintenance of the image forming apparatus, and the like. It is possible to prevent image defects and to form a good image over a long period of time.

(Second Embodiment) A second embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram of an electrophotographic color image forming apparatus according to the present embodiment.

In the image reading section, the original 30 is placed on an original platen glass 31 and is exposed and scanned by an exposure lamp 32 so that the reflected light image from the original 30 is reflected on a mirror 33.
The light is condensed on a full-color sensor 35 by a, 33b, 33c and a lens 34 to obtain a color separation image signal. The color-separated image signal is processed by a video processing unit (not shown) through an amplification circuit (not shown) and sent to an image forming unit.

At this time, in the image forming section, the photosensitive drum 1 as an image carrier is connected to a drum shaft 37 as a holding means, and is driven to rotate in a direction indicated by an arrow by a driving means (not shown).

Around the photosensitive drum 1, a pre-exposure lamp 11, a corona charger 2, a laser exposure optical system 3 as exposure means, a potential sensor 12, and four developing devices 4 of different colors.
y, 4c, 4m, 4Bk, on-drum light amount detecting means 13,
A transfer drum 5 as a transfer device and a cleaning device 6 are arranged.

In the laser exposure optical system 3, the image signal from the image reading unit is converted into an optical signal by a laser output unit (not shown), and the converted laser light is reflected by the rotary polygon mirror 3a, and the lens 3b The light is projected on the cylindrical surface of the photosensitive drum 1 through the mirror 3c.

At the time of image formation, the photosensitive drum 1 is rotated in the direction of the arrow, and the photosensitive drum 1 after having been neutralized by the pre-exposure lamp 11 is uniformly charged by the corona charger 2 so that the light image E To form an electrostatic latent image.

Next, a predetermined developing device is operated to develop the latent image on the photosensitive drum 1 to form a toner image on the photosensitive drum 1 using a resin as a base. The developing device has an eccentric cam 24.
The operations of y, 24c, 24m, and 24Bk make it possible to selectively approach the photosensitive drum 1 in accordance with each separation color.

Further, the toner image on the photosensitive drum 1 is
The image is transferred from a recording material cassette 7 to a recording material supplied to a position facing the photosensitive drum 1 via a transport system and a transfer drum 5. The transfer drum 5 includes a transfer charger 5b, an attraction charger 5c for electrostatically attracting a recording material, and an inner static elimination charger 5d, all of which are in urging contact with the photosensitive drum 1. The transfer drum 5 on which the recording material is electrostatically attracted transfers the toner image on the photosensitive drum 1 onto the recording material by the transfer charger 5b according to the rotation.

As described above, a desired number of color images are transferred to the recording material sucked and conveyed to the transfer drum 5 to form a full-color image.

In the case of forming a full-color image, when the transfer of the four color toner images is completed in this way, the recording material is separated from the separation claw 8.
a, the sheet is separated from the transfer drum 5 by the action of the separation push-up roller 8b, and is discharged to the tray 10 via the heat roller fixing device 9.

Four developing units 4y, 4c, 4m, 4Bk4
Among them, a magnet roller 110 is disposed above the developing device 4y located on the upstream side in the rotation direction of the photosensitive drum 1.

In this embodiment, the magnet roller 1
10 is arranged only above the developing device 4y located on the upstream side in the rotation direction of the photosensitive drum 1, other than this, for example, between the developing devices 4y and 4c, between the developing devices 4c and 4m,
It may be provided at least at any one position between the developing devices 4m and 4Bk.

As shown in FIG. 4, the magnet roller 110 is formed so that the cam 111 can approach or retract from the surface of the photosensitive drum 1.
When the image forming apparatus is not in the image forming operation, the magnet roller 110 is close to the surface of the photosensitive drum 1 as an image carrier while maintaining a predetermined interval. For this reason, even if metal powder is generated by service maintenance or the like and falls along the surface of the photosensitive drum 1, it can be collected by the magnetic force of the magnet roller 110 before approaching the developing device 4.

On the other hand, when the image forming apparatus starts an image forming operation, the photosensitive drum 1 starts rotating, but writing of the latent image is not performed until the rotation is stabilized. In the meantime, the magnet roller 110 is rotationally driven at a position close to the photosensitive drum 1 so that the surface of the photosensitive drum 1 and the surface of the magnet roller 110 have the same speed. During this time the magnet roller 1
By 10, the metal powder attached to the surface of the photosensitive drum 1 is collected. Thereafter, when the rotation of the photosensitive drum 1 is stabilized,
The magnet roller 110 is moved by the action of the cam 111 as shown in FIG.
To the position indicated by the alternate long and short dash line shown in FIG.

With this configuration, it is possible to arrange a member having magnetic force close to the surface of the photosensitive drum 1 without adversely affecting the formation of a latent image, and to more reliably collect foreign matter as metal powder. Becomes possible.

As described above, the image forming apparatus according to the present embodiment can maintain a good image without image defects.

(Third Embodiment) A third embodiment of the present invention will be described. FIG. 5 is a schematic configuration diagram of a toner supply mechanism to a developing device of the electrophotographic color image forming apparatus according to the present embodiment.

In the figure, the non-magnetic toner, which is a resin powder, is stored in a hopper container 120, and a replenishment operation is performed as needed so that the toner concentration of the developer in the developing container 73 falls within a predetermined range. The replenishment is performed by the operation of the drive motor 128 and the clutch 129, and the hopper container 12
0 is first sent to the conveyance path 122 through the opening 124 by the rotation of the screw 121,
3 is conveyed to the opening 126 by rotation. A toner supply port 127 of the developing container 73 is disposed below the opening 126, and the toner is supplied into the developing container 73. The ring-shaped magnet 1 is inserted into the opening 124 of the hopper container 120.
25, and even if foreign matter which is a metal powder is mixed in the hopper container 120, the foreign matter is not conveyed together with the toner and is caught in front of the toner supply port 127 of the developing container 73 as shown in FIG. Can be gathered.

With the above configuration, the developing container 7
It is possible to prevent an image defect due to the entry of the metal powder into the inside 3 beforehand. In the present embodiment, the ring-shaped magnet 125 is disposed in the opening 124 of the hopper container 120. However, if the toner supply path is used, another form, for example, a method in which the screw itself has a magnetic force or the hopper container 12
Even if a magnetic force is given to the bottom of the zero, the same operation and effect as in the present embodiment can be obtained.

[0068]

According to the first aspect of the invention, it is possible to collect metal powder generated inside the image forming apparatus, in particular, metal powder which approaches the developing device along the surface of the image carrier. It is possible to prevent image defects due to metal powder entering the container and maintain a good image for a long time.

According to the second aspect of the present invention, when the image forming apparatus is not operating, the member having magnetic force can be brought closer to the surface of the image carrier, so that metal powder can be collected more reliably. Can be realized.

According to the third aspect of the present invention, a more reliable collection of metal powder can be realized at a stable position with respect to the developing container by a member having magnetic force such as a magnet plate member or a magnet roller. .

According to the fourth aspect of the invention, it is possible to collect metal powder and the like generated during service.

According to the fifth aspect of the present invention, it is possible to prevent the metal powder generated in a state where the image forming apparatus is not operating at the time of maintenance or the like from directly dropping into the developer carrier or the developing container. .

According to the sixth aspect of the invention, even if the metal powder enters the hopper or the like and is conveyed together with the non-magnetic toner into the developing container, the metal powder may enter the developing container immediately before entering the developing container. It is possible to collect, prevent image defects, and maintain a good image for a long time.

According to the seventh aspect of the present invention, it is possible to provide an image forming apparatus capable of preventing an image defect and maintaining a good image for a long time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a developing container according to a first embodiment of the present invention according to the present application.

FIG. 2 is a cross-sectional view around a magnet plate member of the developing container according to the first embodiment of the present invention;

FIG. 3 is a schematic configuration diagram of a color image forming apparatus according to a second embodiment of the present invention;

FIG. 4 is a schematic configuration diagram around a magnet roller in a second embodiment of the invention according to the present application.

FIG. 5 is a schematic configuration diagram of a toner supply mechanism to a developing device of an image forming apparatus according to a third embodiment of the present invention;

FIG. 6 is a schematic configuration diagram of a color image forming apparatus in a conventional example.

FIG. 7 is a sectional view of a developing container in a conventional example.

FIG. 8 is a cross-sectional view around a developing container showing a state when a leak occurs in a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Corona charger 3 ... Laser exposure optical system 4y, 4c, 4
m, 4Bk developing device 5 transfer drum 6 cleaning device 7 recording material cassette 8a separating claw 8b separating and pushing up roller 9 heat roller fixing device 10 tray 11 pre-exposure lamp 12 potential sensor 30 document 31 … Platen glass 32… Exposure lamps 33a, 33
b, 33c Mirror 34 Lens 35 Full color sensor 37 Drum shaft 70 Partition chamber 72 Stirring chamber 72 Developing chamber 73 Developing container 74, 75 Screw 76 Opening 77 Developing sleeve 78 Blade 100 Magnet Plate member 110: magnet roller 120: hopper container 121: screw 122: transport paths 124, 126
.., Opening 125, ring-shaped magnet 128, drive motor 129, clutch 127, toner supply port

Claims (7)

[Claims] An image bearing member having an image bearing surface that moves, and a developer bearing member that faces the image bearing member and carries a developer so as to develop an image on the moving image bearing surface; In an image forming apparatus having a developing container holding a developer to be supplied to an image carrier, a magnetic force is applied to an upstream side where an image bearing surface moves from a position of the developing container where the developer carrier and the image carrier oppose each other. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the member having a magnetic force is provided so as to be movable between a proximity position and a retreat position with respect to the image carrier. 3. The image forming apparatus according to claim 1, wherein the member having a magnetic force is a magnet plate member or a magnet roller provided integrally with the developing container. 4. An image bearing member having an image bearing surface that moves, and a developer bearing member that faces the image bearing member and carries a developer to develop an image on the moving image bearing surface. In an image forming apparatus having a developing container holding a developer to be supplied to an image carrier, a member having a magnetic force is disposed in proximity to at least one portion of a path where foreign matter can fall toward the developer carrier or the developing container. An image forming apparatus comprising: 5. The apparatus according to claim 1, wherein the member having the magnetic force of the developer is provided at at least one position of a path which can be formed at one position toward the developer carrier or the developing container. The image forming apparatus according to any one of the above. 6. A developing device having a toner supply unit provided with a path for supplying a non-magnetic toner into a developing container holding a developer to be supplied to an image carrier, the toner supply path of the toner supply unit being A developing device comprising a member having a magnetic force in at least one of the portions. 7. An image forming apparatus comprising the developing device according to claim 6.