JPH10186855A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the replenished fresh developer from being discharged, and to satisfactorily replacing the deteriorated developer with fresh developer by providing such as first and second transporting members capable of transporting in severally reverse direction while agitating the two component developer, severally arranged in the first and the second developer agitating area. SOLUTION: In this developing device, the first transporting member R1 arranged in the first developer agitating area 43 and the second developer transporting member R2 arranged in the second developer agitating area 44, severally transports the two component developer in the reverse direction while agitates therefor. Then, in the case of consuming the two component developer, the fresh developer is replenished from the developer replenish port 48 in the developer container 41. Moreover, the excess developer is discharged from the developer discharging port 52 formed on the developer flowing direction upstream side adjacent to the developer replenish port 48. Accordingly, fresh developer is replenished in a position adjacent to the developer discharging port 52 on the downstream side, therefore prevented from being discharged in stead of the excess developer, and thus the residual developer is satisfactorily replaced by the fresh developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image formed on an image carrier into a toner image in an image forming apparatus such as an electrophotographic copying machine or a laser printer. And a developing device using a two-component developer composed of a carrier.

[0002]

2. Description of the Related Art Conventionally, in a dry copying machine or the like, a developing device for visualizing, that is, developing an electrostatic latent image on the surface of a photoreceptor using a two-component developer including a toner and a carrier has been used. In such a developing device, while the toner is consumed by the developing operation, the carrier is not consumed and remains in the developing device. Therefore, as the frequency of stirring of the carrier stirred together with the toner in the developing device increases, the situation such as adhesion of the toner to the surface occurs, and the carrier is contaminated and deteriorated. For this reason, as the charging performance of the developer gradually decreases, fogging (when the charging performance of the developer decreases, toner charged to the opposite polarity is generated, and a non-image portion on the photoreceptor is developed during development. This causes image quality defects such as a phenomenon that toner adheres to the image, which is a cause of significantly lowering image quality.

Heretofore, in order to prevent image quality defects such as fogging, it has been necessary to periodically replace the deteriorated developer in the developing container. Then, a great deal of maintenance work is required to replace the developer.
In order to eliminate the need for replacing the developer, a developer consisting of a mixture of a carrier and toner is supplied into the developer container, and the deteriorated developer having a reduced charging performance is discharged from the developer container. There has been proposed a developing device capable of suppressing a decrease in performance. As this kind of technology, the following technology (J.
01) is known.

(J01) Technology described in Japanese Patent Publication No. Hei 2-21591 (Japanese Unexamined Patent Application Publication No. 59-100471) The technology described in this publication discloses that a new carrier is placed in a developing container separately from replenishment of consumed toner. The replenished developer in the excess developer container overflows and is discharged from a developer discharge port provided on the developing container wall surface,
Collected in the developer collection container. By repeatedly supplying and discharging the carrier and the deteriorated developer, the developer that is contaminated and deteriorates in the developing container is replaced with the newly supplied toner and carrier.
Thereby, the charging performance of the developer is maintained, and the deterioration of the image quality is suppressed.

[0005]

[Problems to be solved by the invention]

(Problem of (J01)) In the developing device proposed in (J01), the developer overflowing from the developer outlet is discharged by gravity. However, since the discharging position is not appropriate,
There is a problem that the newly supplied developer is discharged instead of the deteriorated developer.

In view of the above circumstances, the present invention provides the following (O01)
Is the subject of the description. (O01) To prevent the newly replenished developer from being discharged in place of the deteriorated developer, so that the deteriorated developer and the new developer can be exchanged favorably.

[0007]

Next, the present invention devised to solve the above-mentioned problems will be described. Elements of the present invention are used to facilitate correspondence with elements of the embodiments described later. , The reference numerals of the elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

According to the present invention, there is provided a developing device according to the present invention, which has the following requirements. (A01) A two-component developer comprising a toner and a carrier is provided in a developing region ( Q2) and a plurality of magnetic poles (N1, S1, N2, S2, N) on a cylindrical developing sleeve (R0b) conveyed to the developing sleeve (R0b) and a cylindrical surface arranged inside the developing sleeve (R0b).
A developing roll (R0) provided with a magnet roll (R0a) having 3), (A02) a developing roll accommodating section (42) accommodating the developing roll (R0), and a developing roll accommodating section (4).
A first developer stirring area (43) extending in the axial direction of the developing roll (R0) adjacent to 2), and an opposite side to the developing roll (R0) adjacent to the first developer stirring area (43); And the part excluding both ends in the axial direction is the partition wall (4
5) is separated from the first developer stirring area (43), and both ends in the axial direction are separated from the first developer stirring area (4).
3) and the partition (45) and its partition (4)
A second developer stirring area (44) formed between the container outer wall extending along 5) and the container outer wall;
A developer supply port (4) for replenishing new two-component developer inside
8) and a developing container (41) having a developer discharge port (52) for discharging the surplus developer therein;
A first conveying member (R1) arranged in the developer stirring area (43) and agitating while conveying the two-component developer in the axial direction of the developing roll; (A04) arranged in the second developer stirring area (44); A second conveying member (R2) for stirring the two-component developer while conveying the two-component developer in a direction opposite to that of the first conveying member (R1);
(A05) The developer discharge port (52) formed adjacent to the developer supply port (48) and upstream in the developer flow direction.

(Operation of the Present Invention) In the developing device of the present invention having the above-described features, the developing container (41) is provided with a developing roll (R).
0), a first developer stirring area (43) extending adjacent to the developing roll housing section (42) in the axial direction of the developing roll (R0), and the first developing section. A second developer stirring area (4) disposed adjacent to the developer stirring area (43) and on the opposite side to the developing roll (R0).
4). The first developer stirring area (43) and the second developer stirring area (44) are separated by a partition wall (45) except for the both ends in the axial direction, and are connected at both ends in the axial direction. The first transport member (R1) disposed in the first developer stirring area (43) and the second transport member (R2) disposed in the second developer stirring area (44) are
The component developers are stirred while being transported in opposite directions. Therefore, the two-component developer is supplied to the first developer stirring area (4).
It is conveyed and stirred while circulating through 3) and the second developer stirring area (44). The first developer stirring area (4
The two-component developer stirred while being transported in 3) adheres to the developing sleeve (R0b) by the magnetic force of the magnetic pole (N1) of the magnet roll (R0a), and is transported to the developing area (Q2).

When the two-component developer is consumed, a new developer is supplied from the developer supply port (48) into the developing container (41). The surplus developer is supplied to the developer supply port (4).
The developer is discharged from the developer discharge port (52) formed adjacent to 8) on the upstream side in the developer flow direction. Therefore, the new developer is replenished to a downstream position adjacent to the developer discharge port (52), so that the new developer is not discharged instead of the surplus developer, and the surplus developer and the new developer are not discharged. The replacement is satisfactorily performed, a constant charging performance can be stably maintained, and a decrease in image quality can be prevented.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) Embodiment 1 of the developing device of the present invention
(A06) A developer outlet (52) is formed at a downstream end of the first stirring area (43), and the second stirring area (A06) is provided. The developer container (41) in which a developer supply port (48) is formed at the upstream end of (44). (Operation of the First Embodiment) In the first embodiment of the present invention having the above-described structure, the second stirring area (4) of the developing container (41) is used.
The two-component developer is supplied from a developer supply port (48) formed at the upstream end of (4), and the second stirring area (44) is supplied.
And it is stirred and transported in the first stirring area (43). Then, the two-component developer that has deteriorated through the development process or the like is discharged from a developer discharge port (52) formed at the downstream end of the first stirring area (43). Therefore, the replenished two-component developer is not discharged from the developer discharge port (52) immediately after the replenishment.

(Embodiment 2) Embodiment 2 of the developing apparatus according to the present invention is characterized in that any one of the above-mentioned Embodiments 1 and 2 has the following requirements.
7) The developer outlet (52) formed near the magnetic pole (N3) for releasing the developer on the developing sleeve (R0b) of the magnet roll (R0a). (Operation of Second Embodiment) In the second embodiment of the present invention having the above-described configuration, the toner constituting the developer on the developing sleeve (R0b) is consumed by the developing operation. The developer is separated from the developing sleeve (R0b) by the magnetic pole (N3) for separating the developer of the magnet roll (R0a).
The peeled developer is discharged from a developer discharge port (52) formed near the magnetic pole (N3). Therefore, the deteriorated developer used in the developing process is discharged, and the replenished new developer is not discharged.

[0013]

Next, examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In order to facilitate understanding of the following description, arrows X, Y,
The orthogonal coordinate axes X axis, Y axis, and Z axis are defined in the Z direction, and the arrow X direction is forward, the arrow Y direction is left, and the arrow Z direction is upward. In this case, the direction opposite to the X direction (front) (−X direction) is backward, the direction opposite to the Y direction (left) (−Y direction) is right, and the direction Z (upward) is opposite (−Z direction). Is below. Also referred to as the front-rear direction or the X-axis direction including the front (X direction) and the rear (-X direction), and the left-right direction or the Y-axis direction including the left (Y direction) and the right (-Y direction). Good,
It is referred to as a vertical direction or a Z-axis direction including the upper part (Z direction) and the lower part (-Z direction). Furthermore, in the figure, those with "•" in "○" mean arrows pointing from the back of the paper to the front, and those with "x" in "○" are from the table on the paper. It shall mean an arrow pointing to the back.

(Embodiment 1) FIG. 1 is an overall explanatory view of an image forming apparatus provided with a developing apparatus according to Embodiment 1 of the present invention. FIG.
2 is an enlarged explanatory view of the developing device shown in FIG. 1, FIG. 2A is a sectional view taken along line IIA-IIA in FIG. 4, and FIG. 2B is a sectional view taken along line IIB-IIB in FIG. 3 is an explanatory view of the developing container shown in FIG. 2, FIG. 3A is a perspective view of the developing device, and FIG. 3B is a diagram showing a state in which a developer supply member is removed from the developing device. FIG.
FIG. 2B is an enlarged cross-sectional view taken along the line IV-IV of FIG. 2A. FIG. 5 is a sectional perspective view of the main part shown in FIG. In FIG.
The image forming apparatus U includes a digital copying machine U1 as an image forming apparatus main body having a platen glass (transparent document table) A1 on an upper surface, and an automatic document feeder U2 detachably mounted on the platen glass A1. It has. The automatic document feeder U2 has a document feed tray TRk on which documents Gi (i = 1, 2,..., N,..., Not shown) of various sizes to be copied are stacked. I have. The original placed on the original feed tray TRk is a platen glass A1.
The document Gi that has been conveyed to the upper copy position and has been copied is discharged to the document discharge tray TRh.

The copying machine U1 has a UI (user interface), an image input terminal IIT (hereinafter, referred to as IIT) as an image reading unit, and an image as an image recording operating unit sequentially arranged below the platen glass A1. Output Terminal IOT (I
OT) and an IP provided between the IIT and the IOT.
S (image processing system).

The UI is a part where the user inputs an operation command signal such as copy start and the like, and has a display unit, a copy start button, a key for inputting a set number of copies, and the like. The display section displays information relating to the current setting state of the image forming apparatus U. An IIT as an original reading device disposed below the transparent platen glass A1 on the upper surface of the copying machine main body U1 includes an exposure system registration sensor (platen registration sensor) Sp and an exposure optical system 1 arranged at a platen registration position (OPT position). have. The exposure optical system 1 has a movable lamp unit 2, and the lamp unit 2 is configured by integrating a lamp 3 for illuminating a document and a first mirror 4. Further, the exposure optical system 1 has a movable mirror unit 5 that moves at half the speed of the lamp unit 2. This moving mirror unit 5
Is composed of a second mirror 6 and a third mirror 7.

The lamp unit 2 moves in the horizontal direction in FIG. 1 parallel to the original, and the moving mirror unit 5 moves at a speed half the moving speed of the lamp unit 2 and a distance of 1/2. , The distance between the document Gi and the lens 8 is kept constant. At this time, the reflected light of the document Gi illuminated by the lamp 3 passes through the exposure optical system 1 and is converged on a CCD (solid-state imaging device). The CCD has a function of converting the original reflected light converged on the imaging surface into an electric signal.

The IPS adjusts a gain of an analog electric signal of a read image obtained by the CCD (solid-state imaging device) of the IIT, converts the analog electric signal into a digital signal, performs shading correction and the like, and outputs image read data. Means 11
have. The IPS has a write image data output unit 12 to which the image read data output from the image read data output unit 11 is input, and the write image data output unit 12 temporarily stores the image data. It has an image memory 13 to be used. The write image data output means 12
It has a function of performing data processing such as density correction and enlargement / reduction correction on the input image read data and outputting the data as write image data (laser drive data) to the IOT.

The IPS write image data output means 12
The laser drive signal output device 14 of the IOT to which the image write data (laser drive data) output by the IOT is input, outputs a laser drive signal corresponding to the input image data to an ROS (optical write scanning device, that is, a latent image). Forming device). The ROS scans an electrostatic latent image writing position Q1 on the surface of the rotating image carrier 16 with a laser beam modulated by the input laser drive signal. The image carrier 16
Around the peripheral image writing position Q1
A charging charger 17 is disposed upstream of the developing device D, a developing device D is disposed at a developing position Q2 sequentially, and a transfer device 19 is disposed at a transfer position Q3 downstream of the latent image writing position Q1. Further, a cleaner unit 20 is disposed downstream thereof. The developing position Q2 and the transfer position Q3
Between them, a toner image density sensor SNd for detecting the density of a small area toner image (that is, a patch) formed on the image carrier 16 is arranged.

In the copying machine main body U1, a first paper supply tray T1 and a second paper supply tray T2 for sequentially storing sheets, an intermediate tray for temporary stock used for double-sided copying, etc. T0, a third paper supply tray T3, a fourth paper supply tray T4, and a fifth paper supply tray T5 for storing a large number of sheets are detachably stored. And the first paper feed tray T
1, a first delivery roll R11, a first separating roll device R12, and a first takeaway roll device R13 are provided, and a first feed sensor SN1 is provided in front of the first takeaway roll device R13. Are arranged. The same delivery rolls R21,... R51, discarding roll devices R22,.
Takeaway roll devices R23,... R53, feed sensors SN2,. Further, a delivery roll R01, a takeaway roll device R03, a feed sensor SN0, and the like are provided for the intermediate tray T0. The intermediate tray T0 is a tray used when circulating the recording sheet (hereinafter referred to as a sheet) S on which the first copy has been performed at the time of double-sided copying or multiple copying, and retransmitting the recording sheet S to the transfer position Q3.

At the upper right side of the first paper feed tray T1, a manual feed tray 21 is provided. The sheets conveyed from the manual feed tray 21 by the paper feed rollers R6 and R7 and the respective sheets sent out from the respective paper feed trays T1 to T5 pass through the first sheet conveyance path 22 and are transferred to the transfer position Q.
It is to be transported to 3. First sheet transport path 2
2 is the first feed sensor SN
1 and the sheet registration sensor SNy. At the end of the first sheet conveying path 22, the transfer position Q3
A registration gate 23 and a registration roll 24 for temporarily stopping the conveyed sheet S and then carrying the sheet S to the transfer position Q3 are disposed on the upstream side in the sheet conveyance direction. The transfer device 19 arranged at the transfer position Q3 transfers the toner image on the surface of the image carrier 16 to the sheet S passing through the transfer position Q3. After the toner remaining on the surface of the image carrier 16 having passed through the transfer position Q3 is collected by the cleaner unit 20, the surface of the image carrier 16 is recharged with the charger 17 again.
Is charged uniformly.

The sheet S to which the toner image has been transferred at the transfer position Q3 is conveyed to a fixing position Q4 through a conveyance belt 26 of a second sheet conveyance path 25 connected to the sheet discharge tray TR. At the fixing position Q4, a pair of fixing rolls 27 and 2 including a heating roll 27 and a pressure roll 28 are provided.
A fixing device F having a fixing position Q4
Is configured to fix the unfixed toner image on the sheet S passing through the sheet S by heating and pressing. The fixing roll 27
A fixing heater 27h is built therein. In addition,
The surface temperature of the heating roll 27 is detected by a fixing temperature sensor SNt, and a fixing device discharge sensor SNf is disposed adjacent to and downstream of the fixing device F.
The second sheet transport path 25 is provided with a discharge roller 29 for discharging a sheet to a sheet discharge tray TR downstream of the fixing position Q4.

In the second sheet conveying path 25, a switching gate 31 is arranged upstream of the discharge roller 29.
The switching gate 31 is used when switching the transport direction of the sheet S on the second sheet transport path 25 to the direction of the sheet circulation path 32 or the sheet discharge tray TR. The sheet circulation path 32 is connected to a sheet reversing path 33 and the intermediate tray T0 via a switching gate. The switching gate 34 directs the sheet S of the sheet circulation path 32 to the sheet reversal path 33 when performing double-sided copying,
In the case of the multiple copy, the copy is made to go directly to the intermediate tray T0. The sheet-shaped and comb-shaped mylar gate 36 provided in the sheet reversing path 33 allows the sheet S to move downward by elastic deformation when the sheet S passing therethrough is conveyed downward. When the sheet S that has passed through the switch 36 is switched back and conveyed upward, the sheet S is guided in the direction of the intermediate tray T0. Sheet S once stored in intermediate tray T0
Are transported again from the intermediate tray T0 to the transfer position Q3 by the first sheet transport path 22.

In FIG. 2, a developing device D disposed opposite to the image carrier 16 in the developing area Q2 includes a negatively charged toner and a positively charged magnetic carrier.
It has a developing container 41 for storing the component developer. The developing container 41 includes a developing roll accommodating section 42 for accommodating the developing roll R0, and a first
It has a first developer reservoir 43 that is a developer stirring region and a second developer reservoir 44 that is a second developer stirring region adjacent to the first developer reservoir 43. As shown in FIG. 4, between the first developer reservoir 43 and the second developer reservoir 44, partition walls 45 are provided at portions other than both ends thereof, and the first developer reservoir 43 is provided. 43
The second developer reservoir 44 is connected at the connection portions E at both ends in the front-rear direction (X-axis direction). In FIG. 4, a first transport member R is provided in the first developer pool 43.
1 is disposed, and a second transport member R2 is disposed in the second developer reservoir 44.

As shown in FIG. 2, a layer thickness regulating member 47 for regulating the layer thickness of the developer on the developing roll R0 is disposed in the developing roll accommodating section 42. Further, a developer supply port 48 (see FIG. 2B) is formed on the upper surface of the second developer reservoir 44. The second developer reservoir 44 is provided with a developer stagnating portion 50 bulging outward from the outer surface of the developing container 41. The developer retaining portion 50 includes a bottom surface 51a, an upper surface 51b, a side wall 51c parallel to a side wall of the developer reservoir 44, an upstream end wall 51d disposed downstream of the developer conveyed through the developer reservoir 44, And an outwardly protruding wall 51 having a downstream end wall 51e. A developer outlet 52 (see FIG. 4) is formed in the downstream end wall 51e at a portion near the developer reservoir 44. The developer discharged from the developer discharge port 52 is collected in a developer collection container 54 through a developer discharge path 53. The developer reservoir 50 is located in the area of the second developer reservoir 44 shown in FIG. 4 and in the area separated from the first developer reservoir 43 by the partition wall 45 (the connecting portion E at the front and rear ends is formed). (Excluding region). The region is a region in which the flow of the developer is limited in a certain direction by being partitioned by the partition wall 45 from the first developer reservoir 43 in which the surface height of the developer fluctuates due to the rotation of the developing roll R0, In addition, this is a region where the upper surface position of the developer is stable. Note that the developer supply port 48 is formed downstream of the position of the developer retaining section 50 in the transport direction in order to reduce the rate at which the supplied new developer is discharged immediately after the supply. As described above, from the elements indicated by the reference numerals 42 to 53,
The developing containers 41 (42 to 53) in the present embodiment are configured.

In FIG. 4, the first and second conveying members R1 and R2 are constituted by conveying screws mounted around a rotation axis, and have a rear end (-X side end) of each shaft. ), Driven gears G1 and G2 that mesh with each other are fixed. Further, the first transport member R
The first gear G1 is provided at the rear end of the shaft of the developing roll R0 (-X
(Side end). When a rotational force is transmitted to the gear G0 by a developing device motor M (see FIG. 2) M and the gear G0 rotates, the gears G1, G
2 are also configured to rotate in opposite directions. Then, the first and second transport members R1, R2 which rotate integrally with the gears G1, G2 allow the developer in the first and second developer reservoirs 43, 44 as shown in FIG. It is circulating.

The developing roll R0 has a magnet roll R0a fixed to the developing container 41 and a developing sleeve R0b rotatably disposed outside the magnet roll R0a. The magnet roll R0a includes a pickup magnetic pole N1 for attracting the developer to the developing sleeve R0b, a trimming magnetic pole S1 located near the layer thickness regulating member 47, and a transport magnetic pole N2 for transporting the developer. A developing magnetic pole S2 for moving the toner onto the image carrier 16 and developing it into a toner image, and a pick-off magnetic pole N3 for peeling off the developer remaining on the developing sleeve R0b after the developing step from the surface of the developing roll R0. Have been. With the rotation of the developing roll R0, the developer in the first developer pool 43 is changed to the developing roll R0.
And is transported to the developing position Q2.

Referring to FIG. 3B, developer supply cylinder support walls 57 are provided before and after the developer supply port 48. As shown in FIG. 3A, the developer supply cylinder support walls 57, 5
A developer supply cylinder 58 is bonded to 7. FIG. 2, FIG.
In the developer supply cylinder 58, an auger rotating shaft 59 and a developer transport auger 61 mounted around the auger rotating shaft 59 are rotatably disposed. A gear G3 is fixed to one end of the auger rotating shaft 59, and the gear G3 is connected to a motor M for a developing device via a clutch 62 (see FIG. 2A).
It is connected to the. The developing device motor M is driven by a developing device motor drive circuit 63 controlled by a controller C that controls the operation of the copying machine U1.

A developer storage container 64 is connected to one end of the developer supply cylinder 58. The developer storage container 64
A replenishing cylinder 64a is provided on an upper surface of the developer storage container 64, and a two-component developer having a high toner concentration (hereinafter, referred to as a "high-concentration developer") supplied thereto is stored in the developer storage container 64. From the developer storage container 64, the developer supply cylinder 58
The high-concentration developer carried into the developing device
The developer is transported by the developer transport auger 61 which is driven to rotate when the clutch 62 is turned on during the driving of the toner supply device, and is supplied from the developer supply port 48 into the second developer reservoir 44. The replenishment of the high-concentration developer is performed when the in-container toner concentration Tb detected by the in-container toner concentration sensor SNv (see FIG. 2) disposed in the developing container 41 during normal use is equal to or lower than the reference value Tbo. . The replenishment of the high-density developer is performed at a predetermined timing by the toner image density sensor S.
This is also performed when the density of the developed toner image detected by Nd (see FIG. 1) is lower than the reference value. The rotation of the developing device motor M is transmitted to the gear G0 via a clutch 66 (see FIG. 2A).

(Operation of the First Embodiment) In the first embodiment of the developing apparatus of the present invention having the above-described structure, the surface of the image carrier 16 is uniformly charged to a negative polarity by the charging device 17. . Next, exposure is performed by ROS, and an electrostatic latent image is formed on the surface of the image carrier 16. The first and second transport members R1 and R2 accommodated in the first and second developer reservoirs 43 and 44 in the developing container 41 of the developing device D rotate in directions opposite to each other, and a developer supply port is provided. The high-concentration developer supplied from 48 is stirred and conveyed, and is made into a homogeneous two-component developer triboelectrically charged by the mixing action of the toner and the carrier. The uniformly mixed two-component developer is adsorbed (picked up) in a layer on the peripheral surface of the developing sleeve R0b by the magnetic force of the pickup magnetic pole N1 of the magnet roll R0a.
The developer on the surface of the developing roll R0 is
7 to form a uniform layer. The uniform developer layer formed on the surface of the developing roll R0 develops the electrostatic latent image on the image carrier 16 into a toner image in the developing area Q2.
After the development step, the developer remaining on the developing roll R0 is separated (pick-off) from the surface of the developing roll R0 (that is, the developing sleeve R0b) by the pick-off magnetic pole N3, and is stirred and transported again.

A sheet S such as a recording sheet or a transparent transfer material to which the toner image is transferred is taken out from the sheet feeding trays T0 to T5, is conveyed, is temporarily stopped by a registration gate 23, and is then stopped by a registration roll 24. Is transferred to the transfer position Q3 between the image carrier 16 and the transfer device 19 at the timing shown in FIG. At the transfer position Q3, the toner image on the image carrier 16 is transferred onto the sheet S by the transfer device 19. Then, the sheet S on which the toner image has been transferred is fixed by the fixing device F.
The sheet is heated and fixed, and is discharged to the sheet discharge tray TR.
After the transfer of the toner image, the image carrier 16 is thereafter
The toner remaining on the surface is scraped off by the cleaner unit 20.

When the above copying operation is repeated,
The toner in the developer accommodated in the developing container 41 of the developing device D in FIG. 2 is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration decreases.
This change in toner density is detected by an in-container toner density sensor SNv provided in the developing container 41. When the toner concentration Tb in the container falls below an appropriate range required for development, the controller C turns on the clutch 62 to drive the developer transport auger 61, and the developer storage container 6
The high-concentration developer in 4 is supplied into the developing container 41 from the developer supply port 48.

On the other hand, the carrier in the developer in the developing container 41 is not consumed by the developing operation and is agitated together with the toner in the developing container 41, and is influenced by the magnetic force of the magnet roller of the developing roll R0. Also, due to the influence of the contact with the image carrier 16 and the toner, the toner adheres to the carrier surface, and the surface is gradually contaminated and deteriorated. When the carrier deteriorates in this way, the charging performance of the developer is reduced, and a predetermined amount of charge cannot be given to the toner, and the image quality is reduced.
In FIG. 4, the first and second developer reservoirs 43 and 44 are shown.
The developer circulating in the developer reservoir stays in the developer retaining section 50 formed by the outwardly projecting wall 51 formed on the side wall of the developer reservoir 44. The developer that is retained in the developer retaining section 50 and that is close to the developer reservoir 44 moves while being dragged by the developer being conveyed through the developer reservoir. The developer is stored in the developer reservoir 44 on the downstream end wall 51e.
Is discharged to a developer discharge passage 53 from a developer discharge port 52 formed in a portion close to the above. The discharged developer is collected in the developer collection container 54.

The position of the developer supply port 48 is located downstream of the developer discharge port 52 in the developer flow direction. Therefore, the new developer supplied from the developer supply port 48 is stirred without being discharged, and is transported to the developing area Q2. Therefore, the replacement of the deteriorated developer discharged with the new developer in the developing container is performed satisfactorily,
A constant charging performance can be stably maintained, and high image quality can be maintained.

(Embodiment 2) FIG. 6 is an enlarged explanatory view of a main part of Embodiment 2 of the developing device of the present invention. In the second embodiment, elements corresponding to the elements of the first embodiment are denoted by the same reference numerals, and redundant detailed description will be omitted. In the second embodiment, a developer outlet 67 is provided instead of the developer outlet 52 provided on the second developer reservoir 44 side of the first embodiment. The developer outlet 67 is formed in the outer wall of the developing container 41 near the pick-off magnetic pole N3 of the magnet roll R0a and below the developing roll R0. The developer discharge port 67 is provided with a developer discharge shutter 68.
The developer discharge shutter 68 is located on the rear side (−X side, FIG. 6).
Is opened and closed in the front-rear direction (X-axis direction) by a developer discharge solenoid (not shown) arranged on the developer discharge shutter 68). The developer discharge solenoid (not shown) is operated by a developer discharge solenoid drive circuit 69 controlled by the controller C. A developer collection container 72 for collecting the developer discharged through the developer discharge passage 71 is disposed below the developer discharge port 67. In the second embodiment, the developer retaining section 50 of the first embodiment is not formed. In the second embodiment, the two-component developer supplied from the supply port 73a of the developer storage container 73 and stored in the developer supply port 48 of the developer container 41 is stored in the auger rotation shaft 74 and the auger rotation shaft 74. Is supplied by a developer transport auger 76 supported by the developer. The auger rotating shaft 74 is connected to a clutch 62 and a motor for a developing device via a gear G4 at an outer end thereof. When the clutch 62 is turned on, the rotation of the motor is transmitted via the gear G4.

According to the second embodiment, the newly supplied developer is stirred and transported to the developing roll R0. This developer is attracted to the surface of the developing sleeve R0b by the pickup magnetic pole N1 of the magnet roll R0a. The adsorbed developer is transported to the development area Q2, and the image carrier 16
The upper electrostatic latent image is developed into a toner image. After the development process,
The developer remaining on the developing sleeve R0b is separated from the surface of the developing roll R0 by the pick-off magnetic pole N3. Solenoid drive circuit 6 for discharging developer controlled by controller C
9 activates a developer discharge solenoid (not shown),
The developer discharge shutter 68 opens. Thus, the separated developer is discharged from the developer discharge port 67. As described above, the developer outlet 67 is located near the pick-off magnetic pole N3 of the magnet roll R0a and below the development roll R0.
Since the developer is formed on the outer wall, the newly supplied developer is picked up on the developing roll R0 at least once and used in the developing process, and then discharged from the developer discharge port 67. Therefore, it is possible to prevent the carrier or the developer that has just been replenished from being discharged from the developer discharge port as it is.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention can be applied to analog copying machines, printers, facsimile machines, and the like, in addition to digital copying machines. (H02) In each of the above embodiments, instead of forming the developer storage container by one developer storage container 64 containing a high-concentration developer having a high toner concentration, two storage containers of a toner storage container and a carrier storage container are used. , And the supply of toner and carrier can be controlled separately. Further, the developer storage container may be composed of two containers, a container storing a high-concentration developer having a high toner concentration and a toner storage container. (H03) In the present invention, a paddle can be disposed between the developing roll and the first transport member. (H04) The developer retaining portion and the developer discharge path of the present invention can be formed integrally with the container outer wall of the developing container, or can be easily formed on or removed from the container outer wall. (H05) Instead of providing the developer outlet of the present invention on the upper side of the outer wall of the developing container, it is also possible to provide the developer outlet on the lower side of the outer wall of the developing container. Further, the developer retaining section can be omitted.

[0038]

The above-described developing device of the present invention has the following effects. (E01) It is possible to prevent the newly replenished developer from being discharged instead of the deteriorated developer, and to properly exchange the deteriorated developer with the new developer. Therefore, constant charging performance can be stably maintained, and high image quality can be maintained.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus including a developing device according to a first embodiment of the present invention.

2 is an enlarged explanatory view of the developing device shown in FIG. 1; FIG. 2A is a sectional view taken along the line IIA-IIA in FIG. 4;
FIG. 2 is a sectional view taken along line IIB-IIB of FIG.

FIG. 3 is an explanatory view of the developing container shown in FIG. 2;
FIG. 3A is a perspective view of the developing device, and FIG. 3B is a diagram illustrating a state in which a developer supply member is removed from the developing device.

FIG. 4 is an enlarged cross-sectional view taken along the line IV-IV of FIG. 2A.

FIG. 5 is a sectional perspective view of a main part shown in FIG. 4;

FIG. 6 is an enlarged explanatory view of a main part of a developing device according to a second embodiment of the present invention.

[Explanation of symbols]

(N1, S1, N2, S2, N3): magnetic pole, N3: pick-off magnetic pole (magnetic pole for peeling off developer), Q2: developing area, R0
... Developing roll, R0a ... Magnet roll, R0b ... Developing sleeve, R1 ... First transport member, R2 ... Second transport member 41 ... Development container, 42 ... Development roll accommodating section, 43 ... First
Developer stirring area, 44: second developer stirring area, 45: partition wall, 48: developer supply port, 52: developer discharge port

Claims (3)

[Claims] 1. A developing device having the following requirements: (A01) a cylindrical developing sleeve for conveying a two-component developer composed of a toner and a carrier to a developing area; and a developing sleeve disposed inside the developing sleeve. A developing roll provided with a magnet roll having a plurality of magnetic poles on a cylindrical surface, (A0
2) a developing roll accommodating section accommodating the developing roll, a first developer stirring area extending in the axial direction of the developing roll adjacent to the developing roll accommodating section, and adjacent to the first developer stirring area. A portion disposed on the side opposite to the developing roll and excluding both ends in the axial direction is partitioned from the first developer stirring region by a partition wall, and both ends in the axial direction are connected to the first developer stirring region and the partition is formed. A second developer stirring area formed between the wall and a container outer wall extending along the partition wall; a developer supply port provided on the container outer wall to supply new two-component developer to the inside; A developer container having a developer outlet for discharging the surplus developer of (A03)
A first transport member disposed in the first developer agitating region and agitating while transporting the two-component developer in the axial direction of the developing roll;
(A04) a second transport member disposed in the second developer agitating region and agitating while transporting the two-component developer in a direction opposite to the first transport member; (A05) adjacent to the developer supply port The developer outlet formed on the upstream side in the developer flow direction. 2. The developing device according to claim 1, wherein the developing device has the following requirements: (A06) a developer discharge port is formed at a downstream end of the first stirring region; The developing container, wherein a developer supply port is formed at an upstream end of the region. 3. The developing device according to claim 2, wherein the developer satisfies the following requirements: (A07) the developer formed in the vicinity of a magnetic pole for releasing the developer on the developing sleeve of the magnet roll. Vent.