JPH1130913A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image high in developing density and high in a quality without causing any density unevenness by providing a developer diffusing means in a supplying port for dropping/supplying a two-component developer into a lower carrying path from an upper carrying path and assisting the stirring function of a developer carrying means. SOLUTION: Upper and lower mixing augers 40a and 40b are rotated so that the two-component developer is supplied, while being stirred/carried in the direction of an arrow (t), in the upper carrying path 38a and further, dropped/supplied into the lower carrying path 38b, through a second supplying port 41b, together with fresh toner supplied from a toner supplying port 42. During the dropping and carrying, the two-component developer and the fresh toner are dropped/supplied into the lower carrying path 38b, while being diffused, by the working of a sieve 43. Moreover, at this time, the stirring of the two- component developer in a developer reservoir and the fresh toner is accelerated by a urethane rubber sheet 44 and the surface of the sieve 43 comes into slidable contact with the sheet 44, so that the two-component developer and the fresh toner the sieve 43 are forcedly dropped and the carrying of them is accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a developing device mounted on an image forming apparatus such as a printer or an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, a magnetic brush developing device for forming a magnetic brush using a so-called two-component developer composed of a toner and a carrier as a developer and developing an electrostatic latent image has a plurality of developing devices. 2. Description of the Related Art With the spread of color image forming apparatuses such as a quadruple tandem type, which are mounted in parallel in the horizontal direction, downsizing in the horizontal direction is required. In response to this, conventionally, JP-A-5-3
As disclosed in Japanese Patent Publication No. 33691, two mixing augers whose transport directions are opposite to each other are arranged on an upper transport path and a lower transport path having a transport path above and below, while stirring the developer in the casing. A vertical developing device that circulates up and down has been developed.

[0003] That is, this vertical developing device is shown in Figs.
As shown in FIG. 0, conveying paths 2a and 2b are provided vertically in the housing 1, and the two-component developer 6 is circulated in the directions of the arrows r and s while stirring the two-component developer 6 using the two upper and lower mixing augers 3 and 4. In the meantime, the two-component developer 6 is supplied to the developing roller 7 by the upper mixing auger 3 to develop the photoconductor 8.

[0004]

However, in such a vertical type developing device, the mixing auger sufficiently agitates the two-component developer in the housing and sufficiently supplies the developing roller with the two-component developer. However, the mixing and auger functions of the two-component developer and the transport function are incompatible functions, and it is difficult to achieve both. The two-component developer must be pushed up, and the mixing auger needs a sufficient transport function in order to eliminate the shortage of toner supply to the developing roller. On the other hand, when the conveying force of the two-component developer is increased, the two-component developer becomes insufficiently agitated, and the toner concentration in the two-component developer supplied to the developing roller becomes non-uniform. Yields
There is a problem that image quality is deteriorated.

In view of the above, the present invention has been made to solve the above-mentioned problem, and in a vertical type developing device in which a two-component developer is circulated in an upper and lower conveying path, the conveying function by a mixing auger is not reduced, and It is an object of the present invention to provide a developing device capable of obtaining an image with good image density, no image unevenness, and high display quality by obtaining sufficient stirring.

[0006]

According to the present invention, there is provided, as a means for solving the above-mentioned problems, an upper conveying path and a lower conveying path which are conducted through first and second supply ports, and a toner and a carrier. A housing for circulating the two-component developer comprising between the upper transport path and the lower transport path, and agitating and transporting the two-component developer provided in the lower transport path in a first direction; A lower transport unit that supplies the upper transport path from a first supply port located downstream in a first direction, and the two-component developer that is provided in the upper transport path and that is supplied from the first supply port; An upper conveying means which stirs and conveys the toner in a second direction opposite to the first direction and supplies it from a second supply port located downstream of the second direction to the lower conveying path and supplies the lower conveying path; The two-component developer is magnetically conveyed, and the toner is transferred to an electrostatic latent image holding unit. A developing means for applying is intended to provide a developer diffusing means for diffusing the two-component developer to be dropped and supplied to the lower transporting path from said second said upper conveying passage is attached to the supply port of the.

In order to solve the above-mentioned problems, the present invention has a two-component developing device having an upper transport path and a lower transport path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower transport unit that supplies the upper transport path to the upper transport path from a first supply port located at a first position, and supplies the two-component developer supplied from the first supply port provided in the upper transport path to the first direction. An upper conveying unit which stirs and conveys the toner in the opposite second direction and drops and supplies it from the second supply port located downstream in the second direction to the lower conveying path; and the two-component developing unit which is supplied from the upper conveying unit. To transfer the agent magnetically and apply the toner to the electrostatic latent image holding means And the step, is intended to provide a developer spreading section that is attached to the second supply port becomes because sieve mesh shape. According to another aspect of the present invention, there is provided a two-component developer including an upper transport path and a lower transport path that are conducted through first and second supply ports. A housing that circulates between the upper transport path and the lower transport path, and that is provided in the lower transport path, agitates and transports the two-component developer in a first direction, and is located downstream of the first direction. A lower conveying means for supplying the upper conveying path from a first supply port, and a first conveying means provided on the upper conveying path.
The two-component developer supplied from the supply port is agitated and transported in a second direction opposite to the first direction, and drops from the second supply port located downstream in the second direction to the lower transport path. An upper conveying means for supplying, a developing means for magnetically conveying the two-component developer supplied from the upper conveying means and applying the toner to the electrostatic latent image holding means; And a developer diffusion means formed by stacking a plurality of mesh sieves.

Further, the present invention provides a two-component developing device comprising an upper conveying path and a lower conveying path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and transported in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower transport path, and the two-component development supplied from the upper mixing auger Transfers the agent magnetically to the electrostatic latent image holding means A developing means for applying the toner, and a developer diffusion means attached to the second supply port and diffusing the two-component developer dropped and supplied from the upper transport path to the lower transport path. is there.

In order to solve the above-mentioned problems, the present invention provides a two-component developing device having an upper conveying path and a lower conveying path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and conveyed in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower conveying path and supplied thereto, and the two-component developer supplied from the upper auger Is transferred magnetically, and the toner is A developing means for applying is intended to provide a developer spreading section that is attached to the second supply port becomes because sieve mesh shape.

In order to solve the above-mentioned problems, the present invention provides a two-component developing device having an upper conveying path and a lower conveying path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and transported in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower transport path, and the two-component development supplied from the upper mixing auger Transfers the agent magnetically to the electrostatic latent image holding means A developing means for applying a serial toners, in which providing a developer spreading section that is attached to the second supply port becomes because sieve mesh shape.

In order to solve the above-mentioned problems, the present invention provides a two-component developing device comprising an upper transport path and a lower transport path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and transported in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower transport path, and the two-component development supplied from the upper mixing auger Transfers the agent magnetically to the electrostatic latent image holding means Developing means for applying the toner, developer diffusing means attached to the second supply port and diffusing the two-component developer dropped and supplied from the upper transport path to the lower transport path; And a toner replenishing means for replenishing the upper conveying path with new toner at the supply port side of the toner supply device.

In order to solve the above-mentioned problems, the present invention has a two-component developing device having an upper conveying path and a lower conveying path which are conducted through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and transported in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower transport path, and the two-component development supplied from the upper mixing auger Transfers the agent magnetically to the electrostatic latent image holding means A developing means for applying the toner, a developer diffusing means comprising a mesh sieve and attached to the second supply port, and attached to the upper mixing auger above the second supply port; And a toner replenishing means for replenishing the upper conveyance path with new toner on the second supply port side.

According to another aspect of the present invention, there is provided a two-component developing device having an upper transport path and a lower transport path which are connected through first and second supply ports, and comprising a toner and a carrier. A housing for circulating the developer between the upper transport path and the lower transport path; and a casing provided in the lower transport path for stirring and transporting the two-component developer in a first direction and downstream in the first direction. A lower mixing auger for supplying the upper transport path to the upper transport path from a first supply port located in the first transport port, and the two-component developer supplied to the upper transport path and supplied from the first supply port to the first direction. An upper mixing auger which is agitated and transported in the opposite second direction and is supplied from the second supply port located downstream in the second direction to the lower transport path, and the two-component development supplied from the upper mixing auger Transfers the agent magnetically to the electrostatic latent image holding means Developing means for applying the toner, developer diffusion means attached to the second supply port, and a plurality of mesh sieves stacked on each other; and And a toner replenishing means for replenishing new toner. With the above configuration, the present invention provides a supply port for supplying a two-component developer from the upper conveyance path to the lower conveyance path, by providing a developer diffusion unit that drops while diffusing the two-component developer when falling. By improving the agitating property of the two-component developer near the mouth and assisting the stirring performance of the mixing auger, both the transportability and the agitating property of the two-component developer are excellent, and a sufficient image density can be obtained during development, and The purpose of the present invention is to prevent image density unevenness and improve image quality.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a first embodiment shown in FIGS. FIG. 1 shows a developing roller 11 which is a developing means and has a developing sleeve 11a.
-Component developer 1 consisting of toner and carrier to be supplied to
And a developing device 14 that circulates the photosensitive drum 16 in the housing 13 in a vertical direction, and develops a photosensitive drum 16 serving as an electrostatic latent image holding device.
FIG. 1 is a schematic configuration diagram showing a quadruple tandem color printer 20 that obtains a color image by arranging color printers 20 in parallel along a transfer conveyance belt 18.

Each of the image forming means 17a to 17d includes a charging charger 21 around the photosensitive drum 16 along the rotation direction thereof, and an exposure device 22 for converting an image signal into an optical signal and scanning and exposing the photosensitive drum 16. An exposing unit 23, a developing device 14, a transfer / peeling charger 24, a cleaning device 26, and a charge removing lamp 27 are sequentially arranged. or,
The developing device 14 of each of the image forming units 17a to 17d includes yellow (Y), magenta (M), cyan (C),
The development is performed with a developer composed of a two-component developer composed of black (BK) toner and a carrier.

Below the color printer 20, a paper cassette unit 28 for accommodating the paper P to be supplied to the image forming means 17a to 17d is removably mounted, and the paper P is manually supplied to the right side of the color printer 20. A manual feed tray 30 for paper is provided. And the transfer conveyance belt 18
Further upstream, the paper cassette 28 and the manual feed tray 3
The first and second pickup rollers 31a and 31b that take out the sheet P from the sheet No. 0, a transmission roller 32, and a registration roller 33 are provided, and a fixing roller 34, a sheet discharge roller 36, a sheet discharge tray 37 are arranged.

Next, the developing device 14 will be described in detail. Negatively charged toner having an average volume particle size of about 8 μm and a particle size of 50 to 70
A two-component developer 12 containing a magnetic carrier made of iron powder of μm is stored, and the upper transport path 38a of the casing 13 is partitioned by a partition 13a into an upper transport path 38a and a lower transport path 38b.
Inside, an upper mixing auger 40a is provided to supply the two-component developer 12 to the developing roller 11 while stirring and transporting the two-component developer 12 in the direction of arrow t which is the second direction. 42
Is a toner replenishing port for replenishing new toner in the upper transport path 38a. At the leading end in the direction of the arrow t corresponding to the toner drop position by the toner replenishing port 42, two toner supply ports are provided. Second to drop component developer 12
Supply port 41b is formed.

A lower mixing auger 40b is provided in the lower transport path 38b to agitate and transport the two-component developer 12 dropped and supplied from the second supply port 41b in the first direction indicated by an arrow u. It has become. Two-component developer 1 is provided at the tip of the lower transport path 38b in the direction of arrow u in the upper transport path 38a side.
A first supply port 41a for supplying the second 2 is formed, and the two-component developer 12 is circulated in the housing 13 in the arrow t direction and the arrow u direction via the first and second supply ports 41a and 41b. .

The second supply port 41b has an upper conveying path 38a.
Is a developer diffusion means for diffusing the two-component developer 12 and the new toner replenished from the toner replenishment port 42 which have been agitated and conveyed in the interior when the toner falls into the lower conveyance path 38b. A mesh sieve 43 having a mesh size of 750 μm is attached. At the position facing the sieve 43 of the upper mixing auger 40a, the developer 12 in the developer reservoir 38c downstream of the upper transport path 38a in the direction of the arrow t and the toner to be replenished are improved in agitation and fluidity is increased. Mixing auger 40a to enhance
A urethane rubber sheet 44, which is a stirring means, is slidably brought into contact with the sieve 43 with the rotation of. Reference numeral 46 denotes a doctor blade that regulates the thickness of the magnetic brush 12a formed around the developing roller 11.

Next, the operation will be described. A color printer 2 is input by a print start input from an operation input unit (not shown)
When a color image signal is sent to the exposure device 22,
The image forming units 17a to 17d are driven, and the image forming process is sequentially performed on the photosensitive drum 16 according to the rotation in the direction of the arrow v. As a result, each photoconductor drum 16 is charged by the charging charger 21, and then yellow,
An electrostatic latent image is formed by irradiating magenta, cyan, and black image light, and further developed by the developing device 14 to form a toner image of each color. It will be transcribed.

During the formation of the toner image of each color on the photosensitive drum 16, in the paper feed cassette device 28, the paper P is taken out, temporarily stopped at the position of the registration roller 33, and then placed on the photosensitive drum 16. Are transferred to the transfer position of the transfer / conveyance belt 18 in synchronization with the toner images of the respective colors, and yellow, magenta, cyan, and black toner images are sequentially multiplex-transferred from the photosensitive drums 16. Thereafter, the sheet P is peeled from the transfer / conveyance belt 18, conveyed to the fixing roller 34, heat-fixed the toner image to complete the image, and then discharged onto the discharge tray 37 by the discharge roller 36.

On the other hand, in each of the image forming units 17a to 17d, after the transfer of the toner image, the image forming unit 17 is brought into a state in which the next image can be formed via the cleaning device 26 and the charge removing lamp 27, and the above printing operation is repeated until the required number of sheets is reached. It will be.

Next, the operation of the developing device 14 will be described in detail. In the developing device 14 by starting printing,
The upper and lower mixing augers 40a and 40b rotate, and supply the two-component developer 12 to the developing roller 11 while stirring and transporting the two-component developer 12 in the upper transport path 38a in the direction of arrow t. The toner is supplied to the lower transport path 38b together with new toner supplied from the supply port 42. This second
When the toner is dropped and supplied at the supply port 41b, the two-component developer 12 and the new toner are moved by the operation of the sieve 43 in FIG.
As shown in (1), it is dropped and supplied to the lower transport path 38b while being diffused. At this time, the urethane rubber sheet 44 promotes the stirring of the two-component developer 12 and the new toner in the developer pool 38c, and the surface of the sieve 43 is slid in contact with the two-component developer 12 above the sieve 43 and the new toner. Such toner is forcibly dropped and its conveyance is promoted.

In the lower conveying path 38b, the two-component developer 12 that has been dropped while being diffused by the sieve 43 is stirred and conveyed in the direction of arrow u, and the upper conveying path 38 is supplied from the first supply port 41a.
a.

On the other hand, in the developing roller 11, the magnetic brush 12 is rotated by the rotation of the developing sleeve 11a in the direction of arrow w.
a is formed, the layer thickness is regulated by a doctor blade 46, and development is performed at a development position facing the photosensitive drum 16. Thereafter, the two-component developer 12 remaining on the peripheral surface of the developing sleeve 11a is transferred to the lower conveying path 38b as indicated by the arrow x.
And is agitated and transported in the direction of arrow u by the lower mixing auger 40b.

With this configuration, in the vertical developing device 14 for saving space, the sieve 43 is provided at the second supply port 41b, so that the two-component developer 12 is diffused in the upper transport path. Since the developer is dropped and supplied from the lower conveying path 38b to the lower conveying path 38b, the shortage of the stirring function caused by securing the good conveying properties by the mixing augers 40a and 40b is compensated for, and sufficient stirring properties can be obtained. It is possible to form an image with high display quality, which can obtain a density and has no density unevenness.

Next, the present invention will be described with reference to a second embodiment shown in FIGS. The developing device 47 according to the second embodiment is different from the first embodiment in the structure of the upper mixing auger and the developer diffusing means for diffusing the two-component developer 12 at the second supply port 41b. However, since the rest is the same as the first embodiment,
The same parts are denoted by the same reference numerals, and description thereof will be omitted. In the present embodiment, compared to the first embodiment, the use of a coarse sieve with an aperture that is excellent in falling fluidity but inferior in diffusivity is used to supplement the diffusivity.
The sieve has a double structure.

That is, the second supply port 4 of the second embodiment
Reference numeral 1b denotes a developer diffusion means for diffusing the two-component developer 12 and new toner supplied from the toner supply port 42 when falling into the lower conveyance path 38b, and is made of stainless steel which is a non-magnetic metal. As shown in FIG. 7, a double sieve 48 made by shifting the mesh phase is attached to two mesh sieves 48a having a mesh size of 1.5 mm.

Since the openings of the sieve 48a are rough and do not hinder the falling fluidity of the two-component developer 12, the upper conveying path 38
The urethane rubber sheet attached in the first embodiment is not required and is not attached to the upper mixing auger 50 for stirring and transporting the two-component developer 12 at a.

Thus, in the developing device 47, while the two-component developer 12 is circulated in the upper and lower transport paths 38a and 38b in the directions indicated by the arrows t and u, the toner is supplied from the toner supply port 42 to the second supply port 41b. With the new toner to be replenished, the toner is dropped and supplied to the lower transport path 38b while being diffused in two stages as shown in FIG. 7 by the action of the double sieve 48.

In this embodiment, compared to the sieve 43 used in the first embodiment, the sieve 48a has a coarse opening and is inferior in diffusibility of the two-component developer 12 in one sheet. 2
And the two-component developer 12 is diffused in two stages, so that good diffusibility can be obtained. Further, since the openings of the sieve 48a are rough, the sieve 48a can be satisfactorily dropped without urging the urethane rubber sheet to fall as in the first embodiment.

With this configuration, as in the first embodiment, a double sieve 48 provided in the second supply port 41b is provided.
As a result, the two-component developer 12 is diffused and
8a is supplied to the lower conveying path 38b by dropping, and the shortage of the stirring function is compensated for, and sufficient stirring properties can be obtained. Therefore, it is possible to form an image of high display quality without density unevenness.

The present invention is not limited to the above-described embodiment, and can be variously changed in design. For example, the material and particle size of the toner and the carrier of the developer are not limited as long as they are within a range usually used, and the material and the sieve of the sieve are not limited. The size of the aperture is not limited. If it is non-magnetic, it is not limited to a metal material and may be a synthetic resin integrally formed, and the aperture size is also within a range where diffusion of a two-component developer can be obtained. Although there is no limitation as long as it is larger, the thickness is more preferably 500 μm to 2.0 mm because the sieve has a lower diffusibility as the openings become larger. However, from the graph shown in FIG. 8A showing the diffusivity and falling fluidity of the two-component developer in accordance with the aperture when one sieve is used, when the aperture is in the range of 500 μm to 1.18 mm, Although good diffusibility can be obtained, since the drop fluidity is somewhat inferior, the surface of the sieve is slid in contact with the urethane rubber sheet used in the first embodiment to forcibly scrape off the two-component developer, The transportability may be improved.

Further, as can be seen from FIG.
In the range of 4 mm to 2.8 mm, although the drop fluidity is good, the diffusivity is somewhat inferior. Therefore, as shown in the second embodiment, a plurality of sieves are stacked and used to obtain the necessary diffusivity. For example, in the second embodiment in which two sieves are stacked, the diffusivity is significantly improved as shown in FIG. In this case, sieves used repeatedly may not have the same opening size.

[0035]

As described above, according to the present invention, in a vertical developing apparatus, a developer diffusion means is provided at a supply port for supplying a two-component developer from an upper transport path to a lower transport path.
By assisting the stirring function of the developer conveying means, it is possible to obtain a good stirring property while securing a good conveying property, to obtain a high-quality image having a high developing density and no density unevenness, and to achieve a high display quality. Can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a color printer equipped with a developing device according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view of a vertical transport path of the developing device according to the first embodiment of the present invention as viewed from a photosensitive drum side.

FIG. 3 is a schematic cross-sectional view of the developing device according to the first embodiment of the present invention as viewed from the front side.

FIG. 4 is a partially omitted plan view showing a sieve according to the first embodiment of the present invention.

FIG. 5 is a schematic explanatory view showing the operation of the sieve according to the first embodiment of the present invention.

FIG. 6 is a schematic view illustrating a vertical transport path of a developing device according to a second embodiment of the present invention, as viewed from a photosensitive drum side.

FIG. 7 is a schematic explanatory view showing the operation of a sieve according to a second embodiment of the present invention.

FIG. 8 shows falling fluidity and diffusivity of a two-component developer according to the sieve opening of the present invention.
It is a graph which shows the case of two sheets, and (b) is a graph which shows the case of two sieves.

FIG. 9 is a schematic explanatory view of a vertical transport path of a conventional developing device viewed from a photosensitive drum side.

FIG. 10 is a schematic sectional view of a conventional developing device viewed from the front side.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 developing roller 12 two-component developer 14 developing device 16 photosensitive drums 17 a to 17 d image forming unit 20 color printer 38 a upper transport path 38 b lower transport path 40 a upper mixing auger 40 b lower mixing auger 41a: first supply port 41b: second supply port 42: toner supply port 43: sieve 44: urethane rubber sheet

Claims (11)

[Claims] 1. An image forming apparatus comprising: an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer including toner and carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower conveying unit that supplies the two-component developer provided in the upper conveying path and supplied from the first supply port, while stirring and conveying the two-component developer in a second direction opposite to the first direction. An upper conveying unit that drops from a second supply port located downstream in a second direction to the lower conveying path; and an electrostatic latent image that magnetically conveys the two-component developer supplied from the upper conveying unit. Developing means for applying the toner to a holding means; and a developing means attached to the second supply port. Feed path from the developing device, characterized in that comprises a developer diffusing means for diffusing the two-component developer to be dropped and supplied to the lower transporting path. 2. An image forming apparatus, comprising: an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer including a toner and a carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower conveying means for supplying the two-component developer provided on the upper conveying path and supplied from the first supply port, and agitating and conveying the two-component developer in a second direction opposite to the first direction. An upper transport unit that drops from the second supply port located downstream in the direction 2 to the lower transport path; and magnetically transports the two-component developer supplied from the upper transport unit to hold an electrostatic latent image. A developing means for applying the toner to the means, and a mesh sieve. Developing apparatus is characterized by comprising a developer spreading section that is attached to the supply port. 3. An image forming apparatus comprising an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer including a toner and a carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower conveying means for supplying the two-component developer provided on the upper conveying path and supplied from the first supply port, and agitating and conveying the two-component developer in a second direction opposite to the first direction. An upper transport unit that drops from the second supply port located downstream in the direction 2 to the lower transport path; and magnetically transports the two-component developer supplied from the upper transport unit to hold an electrostatic latent image. Developing means for applying the toner to the means, a plurality of developing means attached to the second supply port, Developing apparatus is characterized by comprising a developer diffusing means comprising overlapping Mesh-shaped sieve. 4. An image forming apparatus comprising an upper conveying path and a lower conveying path that are conducted through first and second supply ports, and a two-component developer including a toner and a carrier between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to a path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; Developing apparatus is characterized in that comprises from being attached to the sheet opening the upper conveying passage and a developing agent diffusing means for diffusing the two-component developer to be dropped and supplied to the lower transporting path. 5. An image forming apparatus comprising an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer including toner and carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to a path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; That includes a developer spreading section that is attached to the second supply port becomes because old developing device according to claim. 6. An upper conveying path and a lower conveying path which are conducted through first and second supply ports, and a two-component developer including toner and carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to a path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; It is attached to the supply port, a developing device, characterized in that comprises a developer diffusing means comprising a plurality of stacked mesh sieve. 7. A plate-like stirring means attached to the upper mixing auger above the second supply port and slidingly contacting the developer diffusing means with the rotation of the upper mixing auger. The developing device according to claim 4. 8. An image forming apparatus comprising: an upper transport path and a lower transport path that are conducted through first and second supply ports; and a two-component developer including a toner and a carrier between the upper transport path and the lower transport path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to a path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; A developer diffusing unit attached to a supply port and diffusing the two-component developer dropped and supplied from the upper transport path to the lower transport path; and a new supply port on the second supply port side for the upper transport path. A developing device comprising: a toner replenishing unit for replenishing toner. 9. An image forming apparatus, comprising: an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer including a toner and a carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to a path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; A developer dispersing means comprising a sieve and attached to the second supply port; and a toner supply means for supplying new toner to the upper conveying path on the second supply port side. Developing device. 10. An image forming apparatus comprising an upper conveying path and a lower conveying path which are conducted through first and second supply ports, wherein a two-component developer composed of toner and a carrier is supplied between the upper conveying path and the lower conveying path. And a housing for circulating the two-component developer provided in the lower transport path in a first direction and agitating and transporting the two-component developer from a first supply port located downstream in the first direction. A lower mixing auger to be supplied to the path, and the two-component developer provided in the upper transport path and supplied from the first supply port to be agitated and transported in a second direction opposite to the first direction. An upper mixing auger that drops from a second supply port located downstream in the direction 2 to the lower transport path, and magnetically transports the two-component developer supplied from the upper mixing auger to hold an electrostatic latent image Developing means for applying the toner to the means; A developer diffusion unit attached to the supply port and having a plurality of mesh-shaped sieves stacked thereon; and a toner supply unit for supplying new toner to the upper conveyance path at the second supply port side. A developing device characterized in that: 11. A plate-like stirring means which is attached to the upper mixing auger above the second supply port, and which comes into sliding contact with the developer diffusing means with the rotation of the upper mixing auger. The developing device according to claim 8.