JP4794772B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system or an electrostatic recording system.
[0002]
[Prior art]
When developing an electrostatic latent image on an electrophotographic photosensitive member as an image carrier in a conventional electrostatic recording type or electrophotographic type image forming apparatus, in particular, an image forming apparatus that forms a chromatic image, among others, 2. Description of the Related Art A two-component developing system that uses a non-magnetic toner and a magnetic carrier as a two-component developer is widely used.
[0003]
The two-component development method has advantages such as image quality stability and device durability compared to other currently proposed development methods, while developer deterioration, especially carrier deterioration, due to long-term durability. Is unavoidable, and the developer needs to be replaced.
[0004]
As a method other than the two-component development method, the one-component jumping development method (one-component development method) using magnetic toner does not use a carrier, so that it is not necessary to control the toner concentration in the developer, and the carrier is deteriorated. Since there is no problem, there is no need to replace the developer, and a stable image can be obtained over a long period of time. On the other hand, there is a problem that it is difficult to use as a color toner because of mixing magnetic materials.
[0005]
For this reason, as an image forming apparatus having the advantages of the two developing methods, an image forming apparatus using a one-component developing method for black and a two-component developing method for color has been proposed.
[0006]
[Problems to be solved by the invention]
However, the above-described image forming apparatus having the first developing device adopting the color two-component developing method and the second developing device adopting the one-component developing method using magnetic toner has the following problems.
[0007]
In general, the configuration of an image forming apparatus that employs this method is such that an electrophotographic photosensitive member (photosensitive member), which is an image carrier, is compared with a fixed second developing device that includes a developing unit containing magnetic toner. On the downstream side in the rotation direction, there is provided a first developing device of a rotation switching type in which a plurality of developing devices containing two-component developers are provided in a rotation support device, and the development of the first developing device The developing sleeve, which is a developer carrying member that transports the developer in the developing device to the photosensitive member, provided in each of the developing devices, is rotated in a direction following the photosensitive member, that is, in a direction opposite to the rotating direction of the photosensitive member. Yes.
[0008]
In this configuration, the scattered magnetic toner scattered from the fixed developing device that is the second developing device on the upstream side is on the developing sleeve of the two-component developing device provided in the rotary developing device that is the first developing device. It will adhere to the developer surface.
[0009]
Although the amount of scattered magnetic toner from the fixed developing device is small, it adheres intensively to a part of the coating surface of the two-component developer on the developing sleeve of the two-component developer, so the magnetic toner concentration in that part is It will be quite expensive. When a developing operation is attempted with the two-component developing device in which the magnetic toner scattered from the fixed developing device adheres to the developing sleeve, the magnetic toner on the developing sleeve is developed together with the non-magnetic toner in the two-component developer. As a result, there has been a case in which a black toner, which is a magnetic toner, is mixed in a color image by a two-component developer.
[0010]
In order to prevent this problem, there is a method in which a fixed developing device is arranged downstream of a rotary developing device equipped with a two-component developing device. In this case, the carrier in the two-component developer is mixed in the fixed developing device. As a result, problems such as white streaks due to blade clogging may occur.
[0011]
Accordingly, an object of the present invention is to provide a color image including a second developing device that employs a one-component developing method using magnetic toner, and a first developing device that employs a two-component developing method using toner and a carrier. In the forming apparatus, an image forming apparatus that prevents the scattered magnetic toner from the second developing device from being mixed in the image formed by the first developing device and realizes stabilization of the image quality of the color image with a simple configuration. Is to provide.
[0012]
[Means for Solving the Problems]
The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention includes a rotating image carrier, and a first developing device and a second developing device that develop an electrostatic latent image formed on the image carrier. One developing device includes a plurality of two-component developers containing toner and a carrier. Color A plurality of developing devices; Color Each of the developing devices includes a developer carrier that is a rotating member that faces the image carrier and conveys the toner to the image carrier, and the second developing device includes the image carrier. Provided upstream of the first developing device along the rotation direction of the body. And disposed above the first developing device. In addition, a one-component developer containing magnetic toner is accommodated. black An electrophotographic image forming apparatus, which is a developing device having a developing unit,
The rotation direction of the developer carrying member included in the first developing device is the same direction as the rotation direction of the image carrier,
Using both the first developing device and the second developing device Full color When forming an image, the first developing device Depending on each color toner After the developing operation is performed, the second developing device By black toner An image forming apparatus characterized in that a developing operation is performed.
[0013]
According to an embodiment of the present invention, further, a developer supply container containing the two-component developer for supplying the first developing device, and the developer supply container to the first developing device A developer supply mechanism for supplying a two-component developer; and a developer discharge mechanism for discharging the two-component developer from the first developing device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.
[0015]
Example 1
An electrophotographic image forming apparatus as a first embodiment of the present invention will be described with reference to FIG. The present invention can also be applied to an electrostatic recording type image forming apparatus.
[0016]
In the electrophotographic image forming apparatus according to the present invention, as shown in FIG. 2, a photosensitive drum 1 which is an image bearing member in which a photosensitive layer made of an organic photosensitive member is formed on a cylindrical substrate is an arrow A in FIG. It is rotatably attached with a predetermined peripheral speed in the direction. In this embodiment, a photosensitive layer made of an organic photosensitive material is formed on an aluminum cylindrical substrate having an outer diameter of 50 mm to further improve the releasability of toner as a developer and prevent the photosensitive layer from being scraped. The surface protective layer is provided.
[0017]
The peripheral surface of the photosensitive drum 1 is charged to a predetermined polarity and potential by a corona charger 2 as a charging unit.
[0018]
Then, an output laser beam 4 is generated from the exposure means 3. The output laser beam 4 is modulated (on / off conversion) in response to a pixel signal of image information input from an image reading device (not shown) or an image signal generator such as a personal computer via a print interface, and the laser beam The photosensitive drum 1 is exposed by being deflected by the reflection mirror 5. By scanning exposure of the charged surface of the photosensitive drum 1 with the output laser light 4, an electrostatic latent image of image information is formed on the photosensitive drum 1.
[0019]
The developing device 6 includes a switchable rotary developing device 6a in which a yellow developing device 6Y, a magenta developing device 6M, and a cyan developing device 6C, which are first developing devices, and a black developing device, which is a second developing device. And a fixed developing device 6b having a black developing device 6B.
[0020]
The yellow developing device 6Y, the magenta developing device 6M, and the cyan developing device 6C provided in the rotary developing device 6a contain a two-component developer containing a negative non-magnetic toner of each color and a magnetic carrier. The mixing ratio is about 9: 1 by weight, and toner containing a small amount of carrier is replenished from the replenishment path (not shown) by the consumed amount. The rotary developing device 6a is supported by a rotation support device 6c so as to be rotatable in the direction of arrow B in FIG. 2, and the color developing devices 6Y, 6M, 6C described above sequentially face the photosensitive drum 1 and develop with each color toner. It has come to be.
[0021]
On the other hand, the black developing device 6B provided in the fixed developing device 6b contains magnetic toner (negative polarity). The magnetic toner is a black toner that consumes a large amount of toner, and the developing device 6B containing the toner is configured to be detachable from the image forming apparatus main body 7. When the fixed developing device 6b is mounted on the image forming apparatus main body 7, as shown in FIG. 2, the developing sleeve 621, which is a rotatable developer carrying member, has a small gap (this embodiment) In the embodiment, a developing region for supplying toner held on the developing sleeve 621 toward the photosensitive drum 1 is formed.
[0022]
Further, in the developing container 622 constituting the black developing device 6B, a conveying means 623 for sending magnetic toner to the developing sleeve 621 side is provided, and the toner sent by the conveying means 623 is supplied to the developing sleeve 621. A supply roller 624 is provided inside the container 622 so as to form a nip with the developing sleeve 621. The supply roller 624 is preferably made of a rubber foam material such as polyurethane or silicone in order to achieve stable supply to the developing sleeve 621 and uniform toner application. Further, in the developing container 622, the supply roller 624 is brought into contact with the developing sleeve 621 and rotated in the direction of arrow C in FIG. 2, which is the same direction as the rotating direction of the developing sleeve 621, with a difference in peripheral speed. Is preferred.
[0023]
Further, a regulation for regulating the layer thickness of the toner carried on the developing sleeve 621 above the developing sleeve 621 along the opening of the developing container 622 facing the photosensitive drum 1, which is an installation portion of the developing sleeve 621. A developing blade 625 as a member is provided, and a blowout prevention sheet 626 is provided below the developing sleeve 621 to prevent the toner from blowing out from the lower portion of the toner container 622. A developing bias for the black toner image by the fixed developing device 6 b is applied from the power supply 16.
[0024]
The image forming operation will be described. First, the surface of the photosensitive drum 1 is charged by the corona charger 2. Next, exposure scanning is performed by the exposure unit 3 that is ON / OFF controlled in accordance with image data of the first color (for example, yellow), and an electrostatic latent image of the first color is formed on the photosensitive drum 1. At this time, the yellow developing device 6Y containing the first color yellow toner housed in the rotary developing device 6a is brought into a state facing the photosensitive drum 1, and the first color electrostatic latent image is formed by the yellow developing device 6Y. Developed and visualized. A developing bias is also applied to the rotary developing device 6a from the power source 16 to perform a developing operation. The visualized first toner image is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force. In FIG. In the embodiment, it is driven at 100 mm / s), and is transferred onto the surface of the intermediate transfer drum 8 at the nip portion with the intermediate transfer drum 8 that is rotationally driven in the direction of arrow D.
[0025]
In this embodiment, as the intermediate transfer drum 8, a surface layer made of urethane resin in which carbon, fluororesin, etc. are dispersed is formed on the surface of a conductive elastic layer made of NBR rubber on an aluminum cylinder. Forming a resistance value of about 10 ^Five -10 ^Ten It uses Ωcm and has an outer diameter of 153 mm.
[0026]
When transferring to the intermediate transfer drum 8, a preset voltage is applied to the drum 8 with a polarity opposite to the charging polarity (negative electrode) of the toner. The toner remaining on the photosensitive drum 1 without being transferred to the intermediate transfer drum 8 at the time of this transfer is scraped off by a cleaning blade 9a which is a cleaning means 9 pressed against the photosensitive drum 1, and is disposed in a waste toner container. It is recovered in 9b.
[0027]
Then, after the image formation with the first color yellow toner, the developer that faces the photosensitive drum 1 is moved from the first color yellow developer 6Y to the second color by the rotational movement of the rotation support device 6c of the rotation developing device 6a. In the same manner as in the first color, the second magenta electrostatic latent image formed on the photosensitive drum 1 is developed with the magenta toner. Then, the second color magenta toner image is transferred onto the yellow toner image on the intermediate transfer drum 8. In this manner, the cyan toner images are similarly superimposed and transferred onto the intermediate transfer drum 8, and after the color image is formed by the rotary developing device 6a, a black color image is formed by the fixed developing device 6b.
[0028]
In this way, the exposure process, the development process, and the transfer process are similarly repeated for the four color toners (yellow, magenta, cyan, and black), and each time the color contained in each of the developing devices 6Y, 6M, 6C, and 6B is determined. By sequentially transferring and laminating toner images of different toners to the intermediate transfer drum 8, a color image is synthesized and formed.
[0029]
The cleaning unit 9 brings the cleaning blade 9 a into contact with the surface of the photosensitive drum 1, scrapes the toner remaining on the surface of the drum 1, and after transferring the toner image to the intermediate transfer drum 8, Clean the surface.
[0030]
Further, in FIG. 2, the toner remaining without being transferred from the intermediate transfer drum 8 to the transfer material P is removed from the intermediate transfer drum 8 by the cleaner 10.
[0031]
A transfer material P as a recording material is fed from the feeding cassette 11 to the intermediate transfer drum 8 one by one by a feeding roller 12a and a conveying roller 12b, and transferred to the transfer roller 13 of the secondary transfer unit. By applying a voltage having a polarity opposite to that of the toner from the back side of P, a full color toner image on the intermediate transfer drum 8 side is transferred and formed on the transfer material P.
[0032]
The transfer material P that has received the transfer of the full-color toner image is separated from the intermediate transfer drum 8 and introduced into the fixing unit 14, and is heated and fixed on the toner image and discharged to the discharge tray 15. Yes.
[0033]
As a feature of the present invention, the developing devices 6Y, 6M, and 6C of the rotary developing device 6a containing the two-component developer as the first developing device are provided in the developing devices 6Y, 6M, and 6C. That is, the rotation direction of the developing sleeve 611 conveyed to the drum 1 is the same as the rotation direction of the photosensitive drum 1.
[0034]
Each of the developing devices 6Y, 6M, and 6C provided in the rotary developing device 6a includes at least a developing sleeve 611 and a developing container 612 as in the developing device shown in FIG. 4 described later in the second embodiment. Yes. In this embodiment, a stirring member 616 is provided in the developing container 612.
[0035]
The developing sleeves 611 provided in the developing units 6Y, 6M, and 6C are rotatable, and are held with a slight gap (50 μm to 500 μm in this embodiment) from the photosensitive drum 1 when in the developing position. Thus, a developing region for supplying the toner carried on the developing sleeve 611 toward the photosensitive drum 1 is formed.
[0036]
Therefore, with reference to FIGS. developing The rotation direction of the developing sleeve 611 attached to each of the two-component developing devices 6Y, 6M, and 6C provided in the apparatus 6a and the behavior of the scattered magnetic toner from the fixed rotating apparatus 6b will be described.
[0037]
FIG. 5 shows the behavior of the developer in the conventional example in which the rotating direction of the two-component developing sleeve 611 provided in the developing devices 6Y, 6M, and 6C of the rotating developing device 6a is opposite to the rotating direction of the photosensitive drum 1. Show.
[0038]
The scattered magnetic toner T from the fixed developing device 6b of the second developing device located upstream in the rotation direction of the photosensitive drum 1 is on the developing sleeve 611 of the rotating developing device 6a of the first developing device located downstream thereof. When the conventional image forming apparatus tries to perform a developing operation with the two-component developing devices 6Y, 6M, and 6C of the rotary developing device 6a, the rotation direction of the developing sleeve 611 provided in the developing device 611 is changed to the photosensitive member. Since the rotating direction of the drum 1 is the reverse direction, the scattered magnetic toner T from the developing device B is immediately conveyed to the developing nip portion of the rotating developing device 6a, and together with the nonmagnetic toner in the two-component developer, the magnetic toner T Will also be developed.
[0039]
Since the scattered magnetic toner T moves from the fixed developing device 6b positioned upstream in the rotation direction of the photosensitive drum 1, as shown in FIG. The scattered magnetic toner T adhering to the developer is immediately conveyed to the developing nip portion as the developing sleeve 611 rotates, and is developed on the photosensitive drum 1 as shown in FIG.
[0040]
Therefore, when the developing sleeve 611 is rotated in the same direction as the photosensitive drum 1 as in this embodiment, the scattering that has moved from the upstream with respect to the photosensitive drum 1 can be understood with reference to FIG. The magnetic toner T is not immediately carried to the developing nip portion, but the adhering portion of the scattered magnetic toner T is rotated once according to the rotation of the developing sleeve 611 and then carried to the developing nip portion facing the photosensitive drum 1. It becomes the composition to be.
[0041]
When the scattered magnetic toner T is rotated once in accordance with the rotation of the developing sleeve 611 and conveyed to the developing nip portion, it is sufficiently stirred by the stirring member 616 provided in the developing devices 6Y, 6M, and 6C. As shown in FIG. 1B, the density of the magnetic toner T with respect to the two-component developer is very low, and there is almost no influence of the black toner of the magnetic one-component developer on the color image of the two-component developer.
[0042]
That is, as the developing device, an image including a rotary developing device using a two-component developer of toner and carrier, and a fixed developing device using a magnetic one-component developer positioned upstream of the rotary developing device along the image carrier. In the forming apparatus, the two-component developer on the developer carrier is rotated by rotating the developer carrier opposite to the image carrier in the same direction as the image carrier in the rotary developing device using the two-component developer. The magnetic toner scattered from the fixed developing device adhering to the developer is once transported into the developing device provided in the rotary developing device before being transported to the developing nip, and is sufficiently stirred with the two-component developer in the developing device. Then, the magnetic toner is diffused into the two-component developer, and then the magnetic toner is conveyed onto the developer carrying member with the magnetic toner concentration in the two-component developer being very low. Therefore, the influence of the scattered magnetic toner hardly affects the formed image, and good image formation can be maintained.
[0043]
Here, the dimensions, materials, shapes, and relative arrangements of components other than the developing device and the image carrier described in this embodiment do not limit the scope of the present invention.
[0044]
Example 2
In the configuration of the first embodiment, although the amount of scattered toner from the fixed developing device 6b is very small, when a long-term image forming operation is performed, the developing devices 6Y in the rotary developing device 6a, which is the first developing device, are gradually added. The scattered toner T from the fixed developing device 6b, which is the second developing device located upstream of the rotary developing device 6a, accumulates in 6M and 6C. As a result, there may be a problem of color mixing in the end.
[0045]
Therefore, in this embodiment, in addition to the configuration of the first embodiment, a developer supply container containing toner and a carrier that are developers for supplying to the two-component developing devices 6Y, 6M, and 6C, and a developer supply container Developer supplying mechanism for supplying two-component developer to the two-component developing devices 6Y, 6M, 6C, developer discharging mechanism for discharging the developer from the two-component developing devices 6Y, 6M, 6C, and discharged waste development A developer collection container for storing the developer, so-called trickle development method is used, and the developer in the two-component developer is automatically replaced to newly develop the developer mixed with the accumulated scattered toner T. In this case, the accumulated toner T is prevented from being accumulated.
[0046]
In the following, with reference to FIG. 3 and FIG. 4, the two-component developer supplying mechanism, developer discharging mechanism, and developer discharging mechanism in the rotary developing device 6 a, which are characteristic parts of such an image forming apparatus, are used. The collection of the discharged waste developer will be described in detail. However, the configuration and arrangement of the devices and members described below are not limited to this.
[0047]
In this embodiment, the developer supply container 20a and the developer recovery container 20b are provided with an integrated developer supply mechanism and developer discharge mechanism as shown in FIG. The cartridge 20 is configured and can be easily detached from the rotary developing device 6a.
[0048]
In the present embodiment, the developer cartridge 20 is configured in a state in which a box-shaped developer recovery container 20b is aligned along the peripheral surface of the cylindrical developer supply container 20a. The configuration of is not limited to this.
[0049]
FIG. 4 is a cross-sectional view from the front of the image forming apparatus showing a portion where the developer cartridge 20 is attached to the rotary developing device 6a. The developer cartridge 20 is installed in a state as shown in FIG. 4 for each of the developing devices 6Y, 6M, and 6C of each color of the rotary developing device 6a. In this embodiment, the rotary developing device 6a is disposed inside the developing devices 6Y, 6M, and 6C in the radial direction with respect to the rotation support device 6c, and is connected to the developing container 612 of each developing device.
[0050]
When the developer cartridge 20 shown in FIG. 3 is inserted into the rotary developing device 6a from the front side, the shutter mechanism 21 provided on the surface of the developer recovery container 20b slides, the developer recovery port 22 opens, and further toward the front. By twisting the side handle 23 to the right side, the developer supply container 20a rotates while the developer recovery container 20b is fixed to the image forming apparatus main body 7, and is provided on the peripheral surface of the developer supply container 20a to rotate. The developer supply port 24 that has been sealed up to the previous position is in contact with the developer supply container 20b.
[0051]
When the developer cartridge 20 is detached from the rotary developing device 6a, the openings 23 and 24 are closed by twisting the handle 23 to the left side, so that the powder of toner or the like contained does not come out to the outside. .
[0052]
Further, a stirring member 25 for stirring the developer to be supplied is built in the supply developer accommodating portion 20a. As shown in FIG. 3, the agitating member 25 inside the replenishment developer accommodating portion 20a is such that an agitating spring 25a in which a resin film or the like is spirally driven and rotated by a rigid shaft 25b, and rotates appropriately. As a result, the developer in the replenishment developer container 20a is agitated, and the replenishment of the developer is assisted.
[0053]
On the other hand, as shown in FIG. 4, the developing containers 612 included in the developing devices 6Y, 6M, and 6C are developed at portions facing the developer cartridge 20 in order to deliver the developer to the developer supply cartridge 20. A replenishment conveyance path 613 that can communicate with the developer replenishment port 24 of the developer cartridge 20 and a developer discharge port 614 that coincides with the developer recovery port 22 are provided, and these are provided when the developer cartridge 20 is attached. The openings are opened together with the openings of the developer supply port 24 and the developer recovery port 22, and are closed together with the sealing of the openings 22 and 24 when the cartridge 20 is removed. A replenishment screw 615 is provided in the replenishment conveyance path 613.
[0054]
As a function of the developer replenishing mechanism, the toner consumed by the image formation passes through the developer replenishing port 24 from the replenishing developer accommodating portion 20a by the rotational force and gravity of the stirring member 25 in the developer replenishing container 20a. Then, it passes through the replenishment conveyance path 613 and is conveyed to the replenishment screw 615 disposed in the replenishment conveyance path 613, and is replenished to the developing containers 612 of the developing devices 6 Y, 6 M, and 6 C according to the rotation of the replenishment screw 615.
[0055]
In this way, the replenishment developer is replenished from the developer cartridge 20 to the developing device 6a. The toner / carrier mixing ratio of the replenishment developer is about 9: 1 by weight, but is not particularly limited to this value.
[0056]
That is, the toner amount is overwhelmingly larger than the ratio of the toner and carrier of the two-component developer in the developing container 6a, and considering the volume ratio, it is considered that a small amount of carrier is mixed in the toner. You can also. That is, a small amount of carrier is gradually replenished when the toner consumed by the image formation is supplemented. If the ratio of the developer carrier to be replenished increases, the amount of carrier replacement increases with the same amount of toner replenishment, and the two-component developer in the rotary developing device 6a approaches a fresh state. Consumption increases. For this reason, it is preferable to separately determine an appropriate mixing ratio in each apparatus.
[0057]
The toner (and carrier) replenishment amount is roughly determined by the rotational speed of the replenishment screw 25. This rotational speed is determined by a toner replenishment amount control means (not shown). The toner replenishment amount can be controlled by optically or magnetically detecting the toner density of the two-component developer in the developing devices 6Y, 6M, 6C, or by developing a reference latent image on the photosensitive drum 1 Various methods such as a method for detecting the density of a toner image are known, and any one of the methods can be selected as appropriate.
[0058]
When the toner consumption due to image formation and the replenishment by the developer replenishment mechanism and the toner replenishment amount control means are repeated, the number of carriers replenished at the time of toner replenishment increases in the developing containers 612 constituting the developing devices 6Y, 6M, and 6C. . Since the toner concentration of the two-component developer is kept substantially constant by the toner replenishment amount control means, the total developer amount in the developer container 612 increases.
[0059]
The excess two-component developer is recovered by dropping into the recovered developer accommodating portion 20b the amount that reaches the position of the developer discharge port 614 that coincides with the developer recovery port 22 as a developer discharge mechanism. . It is the stirring member 616 in the developing container 612 that transports the waste developer from the developing container 612 to the developer discharge port 614.
[0060]
A developer discharge restriction valve (not shown) that can be opened and closed is attached to the developer container 612 side of the developer discharge port 614. When the developer container 612 is positioned above the development cartridge 20, the restriction valve described above is provided. Since the developing devices 6Y, 6M, and 6C are rotated to change the attitude of the developing container 612 and the lying developing container 612 is positioned above the developer cartridge 20, the developing device 6Y, 6M, and 6C rotates. As long as the amount of developer in the container 612 does not become excessive, the developer does not move from the developer container 612 to the developer recovery container 20b. Further, even when the developer cartridge 20 is lying on the upper side of the developer container 612, the developer discharge regulating valve is similarly closed, so that the waste developer does not move to the developer container 612.
[0061]
With the above configuration, the magnetic toner mixed in the two-component developing device is sequentially discharged out of the developing device as the developer is discharged. Therefore, in the image forming apparatus of the present embodiment, a large amount of magnetic toner is not accumulated in the developing device of the rotary developing device, so that the image forming by the two-component developer in the rotary developing device can be performed for a long time. Therefore, it is possible to provide a good image with almost no influence of the scattered magnetic toner from the fixed developing device.
[0062]
The developer replenishing mechanism and developer discharging mechanism in the rotary developing device are not limited to the configuration described in this embodiment, and the developer replenishing container and the developer collecting container are not integrated, and are separated. Can be good. The developer recovery container is not always provided, and may be discharged outside the image forming apparatus by the developer discharge mechanism. Further, the developer cartridge may have another configuration.
[0063]
【The invention's effect】
As described above, the image forming apparatus of the present invention is The rotating image carrier and the electrostatic latent image formed on the image carrier are developed. A first developing device and a second developing device, wherein the first developing device includes a plurality of two-component developers containing toner and a carrier. Color With a developer unit, Color Each developing device faces the image carrier and conveys the toner to the image carrier. It is a rotating body The developer carrying member is provided, and the second developing device is provided upstream of the first developing device along the rotation direction of the image carrier. And disposed above the first developing device. In addition, a one-component developer containing magnetic toner is accommodated. black An electrophotographic image forming apparatus which is a developing device having a developing unit Because The rotation direction of the developer carrying member included in the first developing device is the same as the rotation direction of the image carrier, and both the first developing device and the second developing device are used. Full color When forming an image, use the first developing device. Depending on each color toner After the developing operation is performed, the second developing device By black toner Since the developing operation is performed, the influence of the scattered magnetic toner scattered from the second developing device to the developer carrying member of the first developing device hardly affects the formed image, and good image formation can be continued.
[0064]
A developer supply container containing a two-component developer for supplying the first developing device; a developer supply mechanism for supplying the two-component developer from the developer supply container to the first developing device; And a developer discharging mechanism for discharging the two-component developer from one developing device, so that the scattered magnetic toner from the second developing device is not accumulated in the first developing device and can be used for a long time. Thus, good image formation can be maintained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the behavior of scattered magnetic toner T in a developing sleeve 611 of a rotary developing device 6a according to the present invention.
FIG. 2 is a schematic configuration diagram showing a configuration of an image forming apparatus of the present invention.
FIG. 3 is a perspective view showing a developer cartridge 20 according to the present invention.
FIG. 4 is a schematic configuration diagram showing a rotary developing device 6a to which a developer cartridge 20 according to the present invention is attached.
FIG. 5 is an explanatory diagram showing the behavior of scattered magnetic toner T in a developing sleeve 611 of a conventional rotary developing device 6a.
[Explanation of symbols]
1 Photosensitive drum (image carrier)
6 Development device
6a Rotating developing device (first developing device)
6b Fixed developing device (second developing device)
6c Rotation support device
6Y, 6M, 6C Two-component developer (developer)
6B One-component developer (developer)
7 Image forming device
20 Developer cartridge (Developer supply mechanism, discharge mechanism)
20a Developer supply container
20b Developer collection container
21 Shutter mechanism
22 Developer recovery port
23 Handle
24 Developer supply port
25 Stirring member
611, 621 Development sleeve (developer carrier)
612 Developer container
613 Supply transport path
614 Developer outlet
615 Replenishment screw
616 Stirring member
T scattering magnetic toner

Claims (2)

A rotating image carrier, and a first developing device and a second developing device for developing an electrostatic latent image formed on the image carrier, wherein the first developing device comprises toner, A plurality of color developing units containing a two-component developer containing a carrier, each of the plurality of color developing units being a rotating member that faces the image carrier and conveys the toner to the image carrier; A developer carrying member, and the second developing device is provided upstream of the first developing device along the rotation direction of the image carrier , and the first developing device. An electrophotographic image forming apparatus, which is a developing device having a black developing device containing a one-component developer containing a magnetic toner, which is disposed above .
The rotation direction of the developer carrying member included in the first developing device is the same direction as the rotation direction of the image carrier,
In the case of forming a full color image using both the first developing device and the second developing device, after the developing operation with each color toner by the first developing device is performed, the black toner by the second developing device an image forming apparatus comprising the developing operation by the is performed.   Further, a developer supply container containing the two-component developer for supplying to the first developing device, and a developer for supplying the two-component developer from the developer supply container to the first developing device. The image forming apparatus according to claim 1, further comprising: a replenishment mechanism; and a developer discharge mechanism that discharges the two-component developer from the first developing device.

Images