JP2001092251A - Developing machine image-forming device, process cartridge and electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing machine, an image-forming device, a process cartridge and an electrophotographic image forming device, capable of sufficiently stirring two-component developer in a short time and supplying developer in which toner concentration is made uniform to a developer carrier. SOLUTION: This developing machine 3 is equipped with a developer-storing container 7 storing the two-component developer having magnetic particles and toner, a developer stirring and carrying member 12 provided in the container 7 and stirring and carrying the developer, and a toner-replenishing port 15 for replenishing the container 7 with the toner. The device 3 is constituted so that an area where the member 12 is partially exposed from the developer in the carrying direction of the developer by the member 12 is formed, and the area is replenished with the toner from the port 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus for developing an electrostatic latent image formed on an image carrier by, for example, an electrophotographic system or an electrostatic recording system using a two-component developer. Further, the present invention relates to a process cartridge and an electrophotographic image forming apparatus to which the process cartridge is detachable.

Here, as an image forming apparatus and an electrophotographic image forming apparatus, for example, a copying machine, a printer (for example, L
ED printers, laser beam printers, etc.), facsimile machines, word processors, etc.

A process cartridge is a cartridge in which at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is detachably mountable to an electrophotographic image forming apparatus main body. Or a cartridge in which at least the developing means and the electrophotographic photosensitive member are integrally formed, and this cartridge is detachable from the main body of the electrophotographic image forming apparatus.

[0004]

2. Description of the Related Art Conventionally, in order to visualize an electrostatic latent image formed on an image carrier, a two-component developer having a non-magnetic toner (toner) and a magnetic carrier (carrier) has been used as a developer. The so-called two-component developing method has been adopted.

[0005] In the two-component developing method, a developer stirring and conveying member (hereinafter, referred to as a "container") provided in a developer container for storing a developer.
It is called "stirring member". ) To stir the two-component developer and triboelectrically charge the toner, and then transport the toner to a developing sleeve as a developer carrier having a fixed magnet roller inside. Further, the developer is carried while being carried on the surface of the developing sleeve, and supplied to the electrostatic latent image on the image carrier to develop the electrostatic latent image.

In recent years, inexpensive and small-sized developing devices have been increasing for the purpose of increasing needs for color images (for example, color documents) or saving space. Also, a process cartridge system in which an electrophotographic photosensitive member and a process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and which is detachable from an image forming apparatus main body, is widely used. According to this process cartridge system, maintenance of the apparatus can be performed by the user himself without relying on a service person, so that operability can be remarkably improved. Therefore, this process cartridge system is widely used in electrophotographic image forming apparatuses.

In such a developing device and the process cartridge, since the developing device is provided in a limited space around the image carrier, the capacity of storing the developer is small. Therefore, in many cases, a running cost is reduced by separately providing a toner replenishing device (hereinafter, referred to as a “hopper”) so that the toner can be replenished when the toner is consumed.

FIG. 8 shows a schematic cross section of an example of a conventional developing device. First and second stirring members 111 and 112 are disposed inside a developer container 107 that stores a two-component developer. On the upper side of the developer container 107 in the figure, a hopper 114 for storing toner to be replenished is provided.
The lower portion of the hopper 114 opens on a second stirring member 112 provided in the developer container 107, and a toner supply member 116 is rotatably provided near the opening. The toner supply member 116 rotates in response to a signal from a toner sensor 113 which is a means for detecting the concentration of toner in the developer as a means for detecting the amount of developer.
Supplies the toner to the developer container 107.

The toner is supplied from the hopper 114 by rotating a toner supply member 116 in the hopper 114 in response to a toner concentration detection signal from a toner sensor 113 disposed in the developer container 107. When the toner sensor 113 indicates “no toner (developer container 107
Is smaller than a predetermined value level), the toner supply member 116 in the hopper 114 is driven to supply toner. The toner supply amount is given from a function determined in advance based on a value when the toner sensor 113 detects “no toner”.

The toner supplied from the hopper 114 onto the second stirring member 112 provided in the developer container 107 is supplied to the second stirring member 112 and the first stirring member 111.
Is supplied to the entire area of the developer container 107 in the longitudinal direction. The first and second stirring members 111 and 112 have a screw shape, and are each rotatable in the direction of the arrow in the figure. Also, the first and second stirring members 111, 112
Rotates in synchronization with the rotation of the developing sleeve 104 or rotates only when toner is supplied.

Here, in order to form an image having a uniform density, it is essential to stably supply a developer having a uniform toner density to the developing sleeve 104. For this purpose, it is desired that the supplied toner is immediately stirred.

As a shape of the stirring member for the purpose of improving the stirring force, a method in which a spiral blade is formed on the outer periphery of the rotating shaft and the developer is conveyed in the axial direction of the developing sleeve 104 and stirred, or this method is used. In order to further improve the stirring ability in addition to the above, there is known a method of providing a plate-like rib extending radially from a rotation axis to stir and transport the developer.

[0013]

However, in the above-mentioned conventional developing device and process cartridge, it is difficult to always stir and transport the two-component developer having the toner and the carrier satisfactorily through environmental changes and endurance operations. Therefore, there is a problem that image defects such as uneven density occur in the final image.

As a cause of the image density unevenness, there is a case where the stirring force of the stirring member is insufficient. That is, it takes time until the toner replenished from the hopper 114 is evenly loosened in the carrier, and if the developer is supplied to the developing sleeve 104 before reaching a uniform toner concentration, image density unevenness occurs. I do.

Further, the insufficient stirring causes a malfunction of the toner sensor 113 as the developer amount detecting means. That is,
Insufficient agitation of the developer creates a state in which the carrier and the toner remain separated, so the toner sensor 113 should continue to detect "no toner" as the concentration of the toner in the developer and request further toner replenishment. Becomes

Accordingly, an object of the present invention is to supply a developer having a uniform toner concentration, which can sufficiently agitate a two-component developer in a short time, to a developer carrier, and to provide an image defect. An object of the present invention is to provide a developing device, an image forming apparatus, a process cartridge, and an electrophotographic image forming apparatus capable of always stably forming a high-quality image free from defects.

Another object of the present invention is to provide a developing device, an image forming apparatus and a developing method which can sufficiently stir a two-component developer in a short time and can prevent a malfunction of a developer amount detecting means.
An object of the present invention is to provide a process cartridge and an electrophotographic image forming apparatus.

[0018]

The above object is achieved by a developing apparatus, an image forming apparatus, a process cartridge and an electrophotographic image forming apparatus according to the present invention. In summary, according to the first aspect of the present invention, a developer storage container for storing a two-component developer having magnetic particles and a toner, and stirring and transporting the developer provided in the developer storage container A developer agitating and conveying member, and a toner supply port for replenishing toner in the developer storage container;
An area where the developer agitating / conveying member is exposed from the developer is partially formed in a direction in which the developer is agitated and transported by the developer agitating / conveying member, and toner is supplied from the toner replenishing port to the area. Is provided.

According to a second aspect of the present invention, an image forming apparatus which develops a latent image formed on an image carrier using a two-component developer having magnetic particles and toner to form an image on a recording medium (A) a developer accommodating container for accommodating a two-component developer having magnetic particles and a toner, a developer stirring / conveying member provided in the developer accommodating container and agitating and conveying the developer; A toner supply port for replenishing toner in the developer container, and an area where the developer stirring and conveying member is partially exposed from the developer in the developer conveying direction by the developer stirring and conveying member. A developing device formed and supplied with toner from the toner supply port to the area thereof; and (b) a toner supply device for supplying toner into the developer container via the toner supply port. Featured image Forming apparatus is provided.

According to a third aspect of the present invention, there is provided a process cartridge detachably mountable to an electrophotographic image forming apparatus main body, wherein (a) an electrophotographic photosensitive member and (b) process means acting on the electrophotographic photosensitive member. A developer accommodating container accommodating at least a two-component developer having magnetic particles and a toner, a developer stirring / conveying member provided in the developer accommodating container and agitating and conveying the developer; A toner supply port for replenishing toner in the container, and a region where the developer stirring and conveying member is partially exposed from the developer in a direction in which the developer is stirred and conveyed by the developer stirring and conveying member is formed. And a developing device in which toner is supplied from the toner supply port to the area.

According to a fourth aspect of the present invention, there is provided an electrophotographic image forming apparatus for detachably attaching a process cartridge and forming an image on a recording medium, comprising: (a) an electrophotographic photosensitive member; As a process means acting on, a developer accommodating container accommodating at least a two-component developer having magnetic particles and toner, and a developer agitating / conveying member provided in the developer accommodating container and agitating and transporting the developer And a toner replenishing port for replenishing toner in the developer accommodating container, wherein the developer agitating and conveying member is partially moved from the developer in a developer conveying direction by the developer agitating and conveying member. Mounting means for removably mounting a process cartridge having an exposed area formed therein and a developing device in which toner is supplied from the toner supply port to the area; (B) a toner replenishing device for replenishing toner into the developer container via the toner replenishing port; and (c) an electrostatic latent image forming means for forming an electrostatic latent image on the electrophotographic photosensitive member. And an electrophotographic image forming apparatus characterized by having the following.

According to one embodiment of the present invention, a magnetic field generating means is provided near the developer supply port.

According to another embodiment of the present invention, the developer stirring / conveying member has an axis substantially parallel to an axis of a developer carrying member provided in the developer accommodating container. Agitating while transporting the developer, a first developer stirring and transporting member disposed on the developer carrier side,
A second developer stirring / conveying member disposed on the side opposite to the developer carrying member with respect to the first developer stirring / conveying member, and a developer conveying section by the second stirring / conveying member. , An area where the second developer stirring and conveying member is partially exposed from the two-component developer is formed.

According to each preferred embodiment of the present invention, the developer stirring and conveying member has a screw shape having a helical blade at least on the outer periphery of a rotating shaft.

In the first and second aspects of the present invention, according to one embodiment, the developing device is detachable from the image forming apparatus main body.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device, an image forming apparatus, a process cartridge and an electrophotographic image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus using a developing device according to the present invention. According to the present embodiment, the image forming apparatus is an electrophotographic image forming apparatus that forms an image on a recording medium using an electrophotographic image forming process.

The image forming apparatus shown in FIG. 1 has a cylindrical electrophotographic photosensitive member as an image carrier, that is, a photosensitive drum 1, a charging device 2 for charging the photosensitive drum 1, and an electrostatic latent image formed on the photosensitive drum 1. Exposure device 18 to be formed, developing device 3 for visualizing the electrostatic latent image on photosensitive drum 1 using a developer, hopper 14 as a toner replenishing device for replenishing toner to developing device 3, photosensitive drum 1 A transfer device 19 for transferring the toner image formed thereon onto the recording medium P, a fixing device 20 for fixing the toner image transferred to the recording medium P, and a transfer residual toner remaining on the photosensitive drum 1 is removed. Cleaning device 21 for cleaning.

The electrophotographic image forming process will be described.
First, an electrostatic latent image is formed on the surface of the photosensitive drum 1 by an electrostatic latent image forming unit. That is, after the charging device 2 uniformly charges the surface of the photosensitive drum 1, the exposure device 1
8 forms an electrostatic latent image on the photosensitive drum 1 by exposing. Thereafter, the non-magnetic toner in the two-component developer including the magnetic particles (carrier) and the non-magnetic toner (toner) is attached to the electrostatic latent image by the developing device 3, and is visualized as a so-called toner image. . The toner image on the photosensitive drum 1 is supplied to a sheet feeding unit (recording medium conveying unit) such as a sheet feeding cassette 21, a sheet feeding roller 22, and a registration roller pair 23.
On the recording medium P supplied at a predetermined timing to a transfer unit where the photosensitive drum 1 and the transfer device 19 face each other,
The image is transferred by the operation of the transfer device 19. Next, the recording medium P is conveyed to the fixing device 20, and the unfixed toner image is fixed on the recording medium P by heat and pressure to form a permanent fixed image. Thereafter, the recording medium P is discharged out of the image forming apparatus. The transfer residual toner remaining on the photosensitive drum 1 is transferred to the cleaning blade 21 a and the waste toner container 2.
Cleaning is performed by the cleaning device 21 provided with the cleaning device 1b. Image formation is repeated by repeating the above process.

In this embodiment, the photosensitive drum 1 and the charging device 2, the developing device 3 and the cleaning device 21 as process means acting on the photosensitive drum 1 are provided with a frame 25.
To form a process cartridge C that can be attached to and detached from the image forming apparatus main body via mounting means 24 provided on the image forming apparatus main body.

Next, the developing device 3 of this embodiment will be described in more detail with reference to FIG. FIG. 2 is a schematic cross-sectional view of the developing device 3 of the present embodiment as viewed from above.

The developing device 3 stores a two-component developer having a toner and a carrier as a developer in a developer storage container (developer container) 7. A developing sleeve 4 is provided in an opening area of the developer container 7 on the side of the photosensitive drum 1 so as to face the photosensitive drum 1. The developing sleeve 4 has a fixed magnet roller 5 inside. By rotation of the developing sleeve 4 indicated by an arrow in FIG. 1, the developer is attracted around the developing sleeve 4 to form a magnetic brush. In the vicinity of the developing sleeve 4, there is provided a regulating blade 6 for regulating the height of the ears of the magnetic brush to a constant value and attaching an appropriate amount of toner to the electrostatic latent image on the photosensitive drum 1.

In this embodiment, a negatively charged toner having an average particle size (weight average particle size) of 6 μm is used as the toner. The carrier has an average particle size (weight average particle size) of 35 μm,
A magnetic carrier having a saturation magnetization of 205 emu / cm ³ was used. A mixture of toner and carrier at a weight ratio of 8:92 was used as a two-component developer.

The developer container 7 has two developer transport paths (hereinafter simply referred to as “transport paths”) 8 and 9 parallel to the developing sleeve 4. A partition wall 10 substantially parallel to the longitudinal direction of the developing sleeve 4 is provided between the first and second transport paths 8 and 9. Openings are provided at both longitudinal ends of the partition wall 10. The first and second developer conveying paths 8 and 9 are provided with first and second developer stirring and conveying members (stirring members) 11 and 12, respectively. The first and second stirring means 11 and 12 are arranged substantially parallel to the developing sleeve 4. In this embodiment, the first and second stirring members 1
Numerals 1 and 12 are screw-shaped conveying screws provided with spiral blades 11a and 12a in a spiral shape on the outer periphery of the rotating shaft, respectively. In this embodiment, the first stirring member 11 is counterclockwise in FIG. 1, and the second stirring member 12 is
By rotating clockwise, the developer is stirred while being transported in the axial direction. That is, as shown in FIG. 2, the first and second stirring members 11 and 12 convey and stir the developer in the directions of arrows X and Y, respectively.

More specifically, the developer agitated and transported in the second transport path 9 and frictionally charged with the toner is supplied to the opening 1 provided at one longitudinal end of the partition wall 10.
Oa is sent to the first transport path 8, and is supplied to the developing sleeve 4 in the first transport path 8. At the same time, by developing the electrostatic latent image formed on the photosensitive drum 1, the developer having a reduced toner concentration is conveyed through the conveyance path 8, and the opening provided at the other longitudinal end of the partition wall 10 is provided. The flow returns to the transport path 9 again via the section 10b. Thus, the developer circulates inside the developer container 7.

A toner density sensor (toner sensor) 13 as a means for detecting the amount of toner in the developer as a means for detecting the amount of developer is disposed near the uppermost stream of the transport path 9.
That is, as described later, the toner supply port is disposed upstream of the toner supply opening (toner supply port) 15 in the developer conveyance direction. Therefore, the toner sensor 13
Can detect the toner concentration of the developer immediately after participating in the development of the electrostatic latent image on the photosensitive drum 1. In this embodiment, the toner sensor 13 detects the toner concentration (mixing ratio between carrier and toner) by comparing the magnetic permeability of the magnetic carrier with the magnetic permeability of the developer containing the non-magnetic toner and the magnetic carrier. I do. Note that the present invention is not limited to the developer amount detecting means to the toner sensor 13 of the present embodiment, but uses any developer amount detecting means using other detection methods such as capacitance measurement and light transmission type. be able to.

Above the second transport path 9, there is provided a toner supply port 15 which is an opening for toner supply, and a toner supply port provided adjacent to the developing device 3 through the toner supply port 15. The toner is supplied from a supply device (hopper) 14. As shown in FIG. 1, at the lower part of the hopper 14,
A rotary blade 16 as a toner supply member is provided. The rotating blades 16 rotate so as to replenish the toner amount detected by the toner sensor 13 with a toner amount obtained from a predetermined function, and replenish the toner to the transport path 9 via the opening 15. Is done.

As described above, the developer in the developer container 7 circulates and the toner is replenished.
Is supplied with a developer having a predetermined toner concentration.

Here, as described above, in order to form an image having a uniform density, it is essential to stably supply the developing sleeve 4 with a developer having a uniform toner density. For that purpose, the replenished toner must be stirred in a short time.

The present inventors have studied conditions for the toner immediately after replenishment to be sufficiently stirred in a short time and to have a uniform toner concentration. As a result, it has been concluded that the amount of exposure of the stirring member from the upper surface of the developer in the developer container 7 (hereinafter, referred to as “agent surface”) is important. In the case of the developing device of the present embodiment, it is important that the second stirring member 12 in the second transport path 9 provided with the toner supply port 15 at the top is exposed from the developer surface.

More specifically, the carrier and toner constituting the developer have a large difference in specific gravity, and do not mix as they are. Therefore, a shape of the stirring member having an increased stirring force as described above, that is, a shape in which a spiral blade is formed on the outer periphery of the rotating shaft, or a shape in which a plate-like rib extending radially from the rotating shaft is provided is required. It is. However, even when the stirring member having such a shape is used, when the developer covers the stirring member and the toner is newly replenished thereon, the newly replenished toner floats on the developer. Therefore, if the stirring member is not exposed from the developer surface, a sufficient stirring force cannot be exerted. As described above, in order to sufficiently stir the toner and achieve a uniform toner concentration in a short time, the stirring member must be sufficiently exposed from the developer surface.

Here, as a method of changing the amount of exposure of the stirring member from the developer surface of the developer, as shown in FIG. 3, a method (A) in which the diameter of the stirring member is increased (D → D ′), or There are two methods of reducing the amount of developer (H → H ′) (B).

However, in the method (A), the diameters of the stirring members 11 and 12 are increased, and
9 and the developer container 7 need to be enlarged (W →
W '). Therefore, the method (A) is limited in terms of downsizing the developing device and the image forming device or realizing a process cartridge configuration.

When the developer amount is reduced as in the method (B), it is difficult to achieve a satisfactory image density. Further, unduly reducing the amount of the developer is disadvantageous for the deterioration of the developer, which hinders an attempt to extend the life of the developer in order to reduce running costs.

Therefore, according to the present invention, a configuration is provided in which the stirring member can partially form an area exposed from the upper surface of the developer in the developer conveying direction, and toner is supplied to the area. The toner and the carrier can be quickly mixed.

In this embodiment, as shown in FIG. 2, a magnet 17 which is a magnetic field generating means is disposed on the outer wall surface 7a of the developer container 7 adjacent to the transport path 9.

The magnet 17 restrains a part of the developer containing the magnetic carrier and the non-magnetic toner by its magnetic force. By doing so, a region where the developer surface partially changes from the steady state in the second transport path 9 is generated, and the second stirring means 12 forms a portion which is sufficiently exposed from the developer surface. It is possible to do. In this state, the developer is stirred and transported by the second stirring member 12.

More specifically, in this embodiment, FIG.
As shown in FIG. 4A and FIG. First, as shown in FIG. 4A, the magnet 17a is provided on the outer wall surface 7a of the developer container 7 corresponding to the upstream side of the toner supply port 15 in the developer transport direction.
In the area affected by the magnetic field from the magnet 17a,
The developer is restrained and the amount of the developer becomes excessive. Then, on the downstream side in the developer conveyance direction of the region where the developer is constrained, the developer amount becomes too small. Therefore, in the region where the amount of the developer is small, the second stirring member 12 is sufficiently exposed on the surface of the developer, and a sufficient stirring force can be obtained. FIG.
In the arrangement example shown in (a), the position of the toner supply port 15 is
By providing the toner at a position where the amount of developer is too small by the action of the magnet 17a, the toner immediately after replenishment is sufficiently stirred,
It is possible to obtain a developer having a uniform toner concentration in a shorter time than before.

In the example of the arrangement shown in FIG.
A configuration is adopted in which a magnet 17b longer in the developer transport direction than that used in the configuration of (a) is used, and the magnetic field of the magnet 17b reaches a wide area sandwiching the toner supply port 15 in the developer transport direction. In this case, by optimally selecting the magnetic force and the arrangement position of the magnet 17b, it is possible to form an angle on the developer surface of the developer as shown in FIG. By forming an appropriate angle on the developer surface of the developer in the second transport path in this manner, the developer is constrained, and the developer is separated from the magnet 17b in a region on the magnet 17 side where the developer amount becomes excessive. An undersized region can be formed, and the second stirring means 12 can form a portion sufficiently exposed from the developer surface of the developer. Then, by supplying toner to this area, a developer having a uniform toner concentration can be obtained in a short time.

As described above, by appropriately selecting the magnet 17 which generates an appropriate magnetic field capable of restraining the developer, and appropriately selecting its shape and arrangement position, the stirring member is sufficiently exposed from the developer surface. It is possible to form a region of any length, for example, by forming a portion exposed from the developer surface by the second stirring means 12 to be longer in the developer transport direction as shown in FIG. Even when the amount of toner to be replenished is large, a sufficient stirring force can be obtained.

As understood from the above, the present invention can be used by appropriately selecting the magnet 17 without any particular limitation. For example, the intensity of the magnetic field generated on the surface of the magnet can be equal to that of the fixed magnet roller 5 provided in the developing sleeve 4. In this embodiment, a rectangular parallelepiped permanent magnet having a strength (magnetic flux density) of a magnetic field generated on the surface of the magnet of about 900 G (Gauss) is used.

As the magnetic field generating means, not only a permanent magnet but also an electromagnet configured to generate an appropriate magnetic field can be used. Further, it is also possible to change the strength of the magnetic field generated by the magnetic field generating means, the shape of the area to be covered by the magnetic field, and the like as necessary.

In this example, the following comparative experiment was performed to confirm the effects of the present invention.

Using the developing device of this embodiment shown in FIGS. 4A and 4B and a developing device having no magnet 17 as a comparative example, toner is driven while the second stirring means 12 is driven. The toner was replenished through the opening 15 and the toner concentration was measured at various points in the longitudinal direction of the second conveyance path 9 accompanying the stirring and conveyance of the developer. The toner concentration was measured by the magnetic permeability of the developer using the toner sensor 13 and a similar toner sensor as described above.

Further, in the developing devices of the present embodiment and the comparative example, the first and second stirring means are not substantially used in the first and second conveying paths, respectively, and the first and second stirring means are almost completely filled with the developer. The developer to be covered was stored. The toner concentration in the developer to be supplied to the developing sleeve 4 is 8% (carrier: toner = 8: 92), and the toner concentration is reduced to about 6% near the uppermost stream in the developer transport direction in the second transport path. The stirring, conveyance, and toner replenishment were carried out from the state where the toner content decreased. FIG. 6 shows the results.

From the results shown in FIG. 6, FIG. 4 (a) and FIG.
It will be understood that the developing device 3 of this embodiment shown in FIG. 6B sufficiently agitates the toner immediately after replenishment in a short time. As a result, the replenished toner is mixed with the developer in a very short time, and becomes a developer having a uniform toner concentration. Therefore, the developer having a uniform toner concentration can be stably supplied to the developing sleeve 4.

When an image was formed using an image forming apparatus equipped with the developing device 3 of the present embodiment shown in FIGS. 4A and 4B, a good final image without image density unevenness was obtained. Could be obtained.

Further, since the insufficient stirring of the developer is improved, no malfunction of the toner sensor 13 caused by detecting the toner concentration in a state where the toner and the carrier are separated from each other is prevented.

As described above, according to the present invention, the two-component developer can be sufficiently stirred in a short time and the developer having a uniform toner concentration can be supplied to the developing sleeve 4. Further, by swiftly stirring and mixing the two-component developer, erroneous detection of the toner concentration by the toner sensor 13 can be prevented.

In the above embodiment, the image forming apparatus is described as a process cartridge type electrophotographic image forming apparatus. However, the present invention is not limited to this. For example, as shown in FIG. Further, the present invention is naturally applicable to an image forming apparatus in which a developing device is fixed to an image forming apparatus main body and toner can be supplied from a toner replenishing device. In FIG. 7, members having the same functions and configurations as those of the image forming apparatus shown in FIG.

The present invention is also applicable to an image forming apparatus in which the developing device is a cartridge that can be attached to and detached from the image forming apparatus via mounting means provided in the image forming apparatus. I want to be understood. In this case, FIG.
In the above, the photosensitive drum 1, the charging device 2, the developing device 3, and the cleaning device 21 are integrally formed as a process cartridge C by the frame 25, and can be attached to and detached from the image forming apparatus main body via the mounting means 24. Developing device 3
Only the case may be considered in which only the image forming apparatus can be attached to and detached from the image forming apparatus main body via the same mounting means.

[0062]

As described above, the developing device, the image forming device, the process cartridge and the electrophotographic image forming device of the present invention include a developer container for containing a two-component developer having magnetic particles and toner. A developer agitating / conveying member provided in the developer accommodating container for agitating and conveying the developer, and a toner replenishing port for replenishing toner in the developer accommodating container; An area where the developer agitating and conveying member is partially exposed from the developer is formed in the developer conveying direction, and the toner is supplied from the toner supply port to the area, so that the two-component developer can be supplied in a short time. , And a developer having a uniform toner concentration can be supplied to the developer carrier. Further, since the two-component developer can be sufficiently stirred in a short time, malfunction of the developer amount detecting means can be prevented. Therefore,
According to the present invention, a high-quality image free from image defects can always be formed stably.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an electrophotographic image forming apparatus in which a process cartridge configured according to the present invention is detachable.

FIG. 2 is a schematic cross-sectional view of one embodiment of a developing device configured according to the present invention as viewed from above.

FIG. 3 is a schematic cross-sectional view of a developing device for explaining a possible method for exposing a developer stirring and conveying member from a developer.

FIG. 4A is a schematic cross-sectional view of one embodiment of a developing device configured according to the present invention as viewed from above. FIG. 4B is a schematic sectional view of another embodiment of the developing device according to the present invention as viewed from above.

FIG. 5 is a schematic cross-sectional view of the developing device showing a state where an angle is provided to a developer surface of the developer.

FIG. 6 is a graph showing the results of measuring the toner density at various points in the developer transport direction in the developer container in the developing device according to the present invention and a comparative example.

FIG. 7 is a schematic configuration diagram showing another embodiment of the image forming apparatus configured according to the present invention.

FIG. 8 is a schematic sectional view showing an example of a conventional developing device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photosensitive drum (electrophotographic photoreceptor) 2 Charging device 3 Developing device 8 1st developer conveyance path (1st conveyance path) 9 2nd developer conveyance path (2nd conveyance path) 11 1st development Agent stirring and conveying member (first stirring member) 12 Second developer stirring and conveying member (second stirring member) 15 Toner supply port 17 Magnet (magnetic field generating means) 21 Cleaning device

Claims (20)

[Claims] 1. A developer accommodating container for accommodating a two-component developer having magnetic particles and a toner, a developer stirring / conveying member provided in the developer accommodating container for stirring and conveying the developer, And a toner supply port for replenishing toner in the developer container, wherein the developer agitating and conveying member is partially exposed from the developer in a developer transport direction by the developer agitating and transporting member. An area is formed, and toner is supplied to the area from the toner supply port. 2. The developing device according to claim 1, further comprising a magnetic field generating means near said developer supply port. 3. The developer stirring / conveying member includes an axis substantially parallel to an axis of a developer carrying member provided in the developer accommodating container, and agitates while conveying the developer in the axis direction. A first developer stirring and conveying member disposed on the developer carrier side, and a second developer stirring and conveying member disposed on the side opposite to the developer carrier with respect to the first developer stirring and conveying member A region where the second developer stirring and conveying member is partially exposed from the two-component developer in the developer conveying section by the second stirring and conveying member. One or two developing devices. 4. The developing device according to claim 1, wherein said developer stirring and conveying member has a screw shape having a spiral blade at least on an outer periphery of a rotating shaft. 5. The image forming apparatus according to claim 1, wherein the electrostatic latent image formed on the image carrier is developed using a developer, and is detachable from an image forming apparatus main body for forming an image on a recording medium. The developing device according to any one of the above items. 6. An image forming apparatus for developing a latent image formed on an image carrier using a two-component developer having magnetic particles and toner to form an image on a recording medium, comprising: A developer accommodating container for accommodating a two-component developer having a toner, a developer stirring / conveying member provided in the developer accommodating container for agitating and conveying the developer, and replenishing the toner in the developer accommodating container A region where the developer agitating and conveying member is partially exposed from the developer in a direction in which the developer is agitated and transported by the developer agitating and transporting member. An image forming apparatus comprising: a developing device to which toner is supplied from a supply port; and (b) a toner supply device to supply toner to the developer container via the toner supply port. 7. An image forming apparatus according to claim 6, further comprising a magnetic field generating means near said developer supply port. 8. The developer stirring / conveying member includes an axis substantially parallel to an axis of a developer carrying member provided in the developer accommodating container, and agitates while conveying the developer in the axis direction. A first developer stirring and conveying member disposed on the developer carrier side, and a second developer stirring and conveying member disposed on the side opposite to the developer carrier with respect to the first developer stirring and conveying member A region where the second developer stirring and conveying member is partially exposed from the two-component developer in the developer conveying section by the second stirring and conveying member. The image forming apparatus according to 6 or 7. 9. The image forming apparatus according to claim 6, wherein said developer stirring and conveying member has a screw shape having a spiral blade at least on the outer periphery of a rotation shaft. 10. The image forming apparatus according to claim 6, wherein the developing device is detachable from the image forming apparatus main body.
The image forming apparatus according to any one of the above items. 11. A process cartridge detachable from an electrophotographic image forming apparatus main body, comprising: (a) an electrophotographic photosensitive member; and (b) at least magnetic particles and toner as process means acting on the electrophotographic photosensitive member. A developer accommodating container for accommodating a two-component developer, a developer stirring / conveying member provided in the developer accommodating container for stirring and conveying the developer, and for replenishing toner in the developer accommodating container. A region where the developer agitating and conveying member is partially exposed from the developer in the direction in which the developer is agitated and transported by the developer agitating and transporting member. And a developing device to which toner is supplied from the process cartridge. 12. The process cartridge according to claim 11, further comprising a magnetic field generating means near said developer supply port. 13. The developer stirring / conveying member has an axis substantially parallel to an axis of a developer carrying member provided in the developer accommodating container, and agitates while conveying the developer in the axis direction. A first developer stirring and conveying member disposed on the developer carrier side, and a second developer stirring and conveying member disposed on the side opposite to the developer carrier with respect to the first developer stirring and conveying member A region where the second developer stirring and conveying member is partially exposed from the two-component developer in the developer conveying section by the second stirring and conveying member. 11 or 12 process cartridges. 14. The process cartridge according to claim 11, wherein the developer stirring and conveying member has a screw shape having a helical blade at least on an outer periphery of a rotation shaft. 15. The process cartridge, wherein at least one of a charging unit, a developing unit, and a cleaning unit as the process unit and the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge is formed into an electrophotographic image forming apparatus. The process cartridge according to claim 11, wherein the process cartridge is detachable from a main body. 16. An electrophotographic image forming apparatus capable of detachably attaching a process cartridge and forming an image on a recording medium, comprising: (a) an electrophotographic photosensitive member, and at least a process means acting on the electrophotographic photosensitive member. A developer storage container that stores a two-component developer having magnetic particles and a toner, and a developer stirring and conveying member that is provided in the developer storage container and stirs and conveys the developer,
A toner replenishing port for replenishing toner in the developer accommodating container, wherein the developer agitating and conveying member is partially exposed from the developer in a developer conveying direction by the developer agitating and conveying member. Mounting means for removably mounting a process cartridge having an area in which a toner is supplied from the toner supply port to the area, and (b) the developing device via the toner supply port. An electrophotographic image forming apparatus, comprising: a toner replenishing device for replenishing toner in a developer container; and (c) an electrostatic latent image forming unit for forming an electrostatic latent image on the electrophotographic photoreceptor. Forming equipment. 17. An electrophotographic image forming apparatus according to claim 16, further comprising a magnetic field generating means near said developer supply port. 18. The developer stirring / conveying member includes an axis substantially parallel to an axis of a developer carrying member provided in the developer container, and agitates while conveying the developer in the axis direction. A first developer stirring and conveying member disposed on the developer carrier side, and a second developer stirring and conveying member disposed on the side opposite to the developer carrier with respect to the first developer stirring and conveying member A region where the second developer stirring and conveying member is partially exposed from the two-component developer in the developer conveying section by the second stirring and conveying member. 16. An electrophotographic image forming apparatus according to 16 or 17. 19. The electrophotographic image forming apparatus according to claim 16, wherein the developer stirring and conveying member has a screw shape having a spiral blade at least on the outer periphery of a rotating shaft. 20. The process cartridge, wherein at least one of a charging unit, a developing unit, and a cleaning unit as the process unit and the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge is formed into an electrophotographic image forming apparatus. The electrophotographic image forming apparatus according to any one of claims 16 to 19, wherein the electrophotographic image forming apparatus is detachable from a main body.