JP5073963B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus using a two-component developer.

In recent years, along with demands for downsizing and personalization of image forming apparatuses using electrophotographic technology such as copiers and printers, downsizing of developing devices has been attempted. Further, in response to such a request, when the toner runs out, the disposable developing device that is replaced with the developing device, or a latent image carrier (on which an electrostatic latent image of the original image is formed) in addition to the developing device. A so-called process cartridge in which a photosensitive member) and a cleaning unit that removes toner remaining on the photosensitive member are integrated is also widely used.
However, such a miniaturized developing device has a small amount of developer containing the toner and the magnetic carrier. In addition, since the space for the developer agitation unit is also inevitably reduced, the time required for the replenished toner to reach the development area is short, and the agitation between the toner and the magnetic carrier becomes insufficient, resulting in a charge amount of the toner. Becomes smaller, and floating toner is likely to be generated. When floating toner is generated, the background of the transfer paper becomes very dirty, which is not preferable. Such a phenomenon occurs remarkably when the amount of toner replenishment increases, such as when the amount of toner replenishment increases, as in the case of continuously printing a document with a high image area ratio.
In addition, as the machine speed increases, the developer agitating / conveying member rotates at high speed, and the toner is 3 to 12 μm fine particles, so that a part of the replenished toner is scattered without being well agitated with the developer. , Float or move on the developer surface. When such toner is transported to the development roller and transported to the development area, uncharged, reversely charged, and weakly charged poorly charged toner may cause non-image area background contamination, density unevenness, or toner scattering. Arise.

In order to solve such a problem, a scattering prevention member that prevents the toner replenished from the toner replenishing portion from sliding on the surface of the agent and being conveyed to the screw portion on the developing roller side without being charged is provided. It has been proposed (see, for example, Patent Document 1).
However, these means emphasize the uniform dispersion of the toner among the two conditions that must be satisfied before the toner is transported to the developing unit. In other words, the screw portion is provided with a function to uniformly distribute the replenishment toner to the developer, and the toner charging is covered by the rubbing of the developer in the vicinity of the developer regulating blade as before. In such a development system, there is a problem in that the toner is subjected to a large load in the developer reservoir on the back side of the developer regulating blade and the developer deteriorates. Deteriorated toner tends to be weakly charged / reversely charged toner, and after a long-time image forming process, the charge amount distribution is broadened, leading to background contamination and toner scattering. However, if the stress on the back of the developer regulating blade is easily reduced, insufficient charging of the toner may occur, and on the contrary, background stains and toner scattering may increase.

In addition, it has been proposed to increase the charge amount by operating the agent passage amount regulating member in the developing device so as to approach the developing roller (see, for example, Patent Document 2). However, in this configuration, although the rubbing force applied to the agent is increased, the place where the agent is regulated is in the vicinity of the doctor blade. There is also a concern that density unevenness may occur.
In addition, a configuration has been proposed in which the number of fins attached to the downstream side of the screw in the replenishment side stirring chamber is increased from the upstream side to change the agent level in the replenishment side stirring chamber upstream and downstream (for example, Patent Documents). 3).
However, in any of these inventions, it is possible to prevent the topping of the replenished toner, to uniformly disperse the toner, to sufficiently impart the toner, and to weaken the mechanical force applied to the developer as compared with the conventional one, thereby extending the life of the developer. There were points that were insufficient to make it easier.

JP-A-9-106161 JP-A-11-202573 JP 2004-272017 A

In view of the above problems, the present invention can prevent the replenished toner from directly reaching the developing sleeve in a low-charged state or an uncharged state, and when the image forming process is repeated over a long period of time, or consumes less toner. It is an object of the present invention to provide a developing device and an image forming apparatus in which the developer is hardly deteriorated even in a special use state for a long period of time and is free of background stain and toner scattering for a long period of time.
The fundamental idea is that the charging function of the toner is shared by the first developer agitation unit to which the toner is replenished, thereby reducing the burden on the developer as a whole of the developing device and extending the life of the developer. Is.

According to the first aspect of the present invention, there is provided an agitating means for agitating and dispersing the two-component developer composed of the toner and the carrier with two rotatable screws disposed in the developer container and transporting them to a predetermined position. A toner replenishing means for replenishing toner consumed by the development, a toner density detecting means for the developer, and an image for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. A developer containing portion on the side where toner is replenished, a developer containing portion on the side facing the developer carrying member, and a developing side stirring chamber. A developer passing amount regulating member that changes the area of the opening at the opening that delivers the developer from the downstream end of the replenishing side stirring chamber to the developing side stirring chamber, The developer passage amount restricting member is the auxiliary member. A cross-sectional area of the transfer section of the side stirring chamber and the developing side stirring chamber is configured by a shutter member that can change, and the shutter member is a plate-like member inserted downward from the ceiling of the transfer section, The opening area is changed by moving the member up and down, the toner density detecting unit detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting unit detects the reference toner image. When it is detected that the image density has fallen below a predetermined level, the developer passage amount regulating member is actuated to reduce the area of the opening so that the developer is retained upstream of the opening in the developer transport direction. It is characterized by being made small.
According to a second aspect of the present invention, there is provided an agitating means for agitating and dispersing a two-component developer comprising a toner and a carrier with two rotatable screws disposed in a developer container and conveying the mixture to a predetermined position. A toner replenishing means for replenishing toner consumed by the development, a toner density detecting means for the developer, and an image for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. A developer containing portion on the side where toner is replenished, a developer containing portion on the side facing the developer carrying member, and a developing side stirring chamber. A developer passing amount regulating member that changes the area of the opening at the opening that delivers the developer from the downstream end of the replenishing side stirring chamber to the developing side stirring chamber, The developer passage amount restricting member is the auxiliary member. A shutter member capable of changing a cross-sectional area of the transfer portion between the side stirring chamber and the developing side stirring chamber, and the shutter member is a plate-like member that is slidable laterally through the opening of the transfer portion; The opening area is changed by moving the plate-like member left and right, the toner density detecting means detects that the toner density of the developer is not less than a predetermined value, and the image density detecting means is a reference toner. When it is detected that the image density of the image has fallen below a predetermined level, the developer passage amount regulating member is operated, and the developer is retained in the developer conveyance direction upstream of the opening. Characterized by reducing the area

According to a third aspect of the present invention, there is provided an agitating means for agitating and dispersing a two-component developer comprising a toner and a carrier with two rotatable screws disposed in a developer container and transporting them to a predetermined position. A toner replenishing means for replenishing toner consumed by the development, a toner density detecting means for the developer, and an image for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. A developer containing portion on the side where toner is replenished, a developer containing portion on the side facing the developer carrying member, and a developing side stirring chamber. A developer passing amount regulating member that changes the area of the opening at the opening that delivers the developer from the downstream end of the replenishing side stirring chamber to the developing side stirring chamber, The developer passage amount restricting member is the auxiliary member. It is composed of a shutter member capable of changing the cross-sectional area of the transfer section of the side stirring chamber and the development side stirring chamber, and the shutter member is a plurality of parallel plate-like members provided in the transfer section, The plate-like member is configured to change the opening area by changing the angle. The toner density detecting means detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting means is a reference. When it is detected that the image density of the toner image has fallen below a predetermined level, the developer passage amount regulating member is actuated so as to retain the developer upstream of the opening in the developer transport direction. The area is reduced .

According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, the toner concentration detecting means detects that the toner concentration of the developer is not less than a predetermined value, and When the image density detecting means detects that the image density of the reference toner image has fallen below a predetermined level, the advection speed from the downstream end of the replenishing side stirring chamber to immediately after being transferred to the developing side stirring chamber V1 and the average advection speed V2 at which the developer recirculates once in the developing device,
0.6 <V1 / V2 <1
The developer passage amount regulating member is operated so as to satisfy the above relationship .
According to a fifth aspect of the present invention, at least two of the latent image carrier, the charging device, and the latent image carrier cleaning device are integrated with the developing device according to any one of the first to fourth aspects. Features a process cartridge .

According to a sixth aspect of the invention, there is provided an image forming apparatus that includes the developing device according to any one of the first to fourth aspects and records an image formed by a series of image forming processes on a recording medium. .

According to the present invention, since the advection speed from the downstream end of the replenishment-side stirring chamber to just after being transferred to the development-side stirring chamber is restricted, the agent stays in the replenishment-side stirring chamber, and the developer is rubbed. The power is increased, the dispersion of the replenishing toner is promoted, and at the same time the charging of the toner is promoted.
By changing the cross-sectional area of the developer path according to the charged state of the developer in the developer unit, it is possible to apply a rubbing force without excess or deficiency, and developer deterioration due to applying an excessive rubbing force Can be suppressed.

FIG. 1 is an internal configuration diagram of a color image forming apparatus to which a developing device according to an embodiment of the present invention is applied.
In the figure, reference numeral 100 is a copying apparatus main body, 200 is a paper feed table on which the copying apparatus main body 100 is placed, 300 is a scanner (reading optical system) mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (400) further mounted thereon. ADF) is shown respectively. Other symbols are directly cited in the detailed description.
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. The image forming apparatus shown in the figure is specifically a tandem indirect transfer type electrophotographic copying apparatus. An endless belt-like intermediate transfer member 10 extending in the lateral direction is provided at the center position of the copying apparatus main body 100. In the illustrated example, the intermediate transfer member is wound around three support rollers 14, 15, and 16 so as to be able to rotate and convey clockwise in the drawing. In this illustrated example, an intermediate transfer body cleaning device 17 that removes residual toner remaining on the intermediate transfer body 10 after image transfer is provided to the left of the second support roller 15 among the three support rollers. Further, among the three support rollers, the intermediate transfer member 10 stretched between the first support roller 14 and the second support roller 15 has black, yellow, magenta, and cyan along the transport direction. The tandem image forming unit 20 is configured by arranging the four image forming units 18 side by side. An exposure device 21 is further provided immediately above the tandem image forming unit 20 as shown in FIG. On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer body 10 from the tandem image forming unit 20. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 23, and is pressed against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet. A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt. The secondary transfer device 22 described above also has a sheet transport function for transporting the image-transferred sheet to the fixing device 25. In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming unit 20 described above. Is provided.

  Now, when making a copy using this color electrophotographic apparatus, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it. When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. Immediately, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read. When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is rotationally driven by a drive motor (not shown), and the other two support rollers are driven to rotate, so that the intermediate transfer body 10 is moved. Rotate and convey. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40.

  Along with the conveyance of the intermediate transfer member 10, these single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10. On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, thereby separating rollers 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped. Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet. The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image. Are discharged and stacked on the discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56. On the other hand, the intermediate transfer body 10 after the image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer body 10 after the image transfer, so that the tandem image forming unit 20 can prepare for another image formation.

FIG. 2 is a view showing an embodiment of a developing device used in the image forming apparatus.
In the figure, reference numeral 61 denotes a developing device, 65 denotes a developer container, 66 denotes a toner replenishment side stirring screw, 67 denotes a developer carrier side stirring screw, 68 denotes a developer carrier (developing roller), 75 denotes a toner density sensor, Reference numeral 77 denotes a doctor blade, 86 denotes a supply side stirring chamber, and 87 denotes a development side stirring chamber.
FIG. 3 is a longitudinal sectional view of the developing device.
In the figure, reference numeral 78 denotes a developer passage amount regulating member, and 80 denotes a threshold plate.
In the tandem image forming unit 20 described above, each image forming unit 18 includes a charging device, a developing device, a primary transfer device, a photoconductor cleaning device, a static elimination device, and the like around a drum-shaped photoconductor 40. .
The developing device 61 includes, in a developer container 65, a toner replenishment side stirring screw 66 as a developer stirring / conveying means, a developer carrier side stirring screw 67, and a developer carrier (developing roller) 68. A supply port (not shown) is provided on the outer wall of the container of the first developer stirring chamber 86, and toner is supplied from a toner supply device (not shown). (Hereinafter, the first developer stirring chamber is referred to as a replenishment side stirring chamber.) The toner replenishment side agitating screw 66 includes the toner replenished from the toner replenishing device and the developer in the developer container 65 (magnetic particles and toner). And a two-component developer). Further, the stirring screw 67 in the second developer stirring chamber 87 (on the developer carrying member side) stirs and conveys the developer in the developer container 65. (Hereinafter, the second developer stirring chamber is referred to as a development side stirring chamber.)
As shown in FIG. 3, the replenishing side stirring chamber and the developing side stirring chamber are partitioned by a partition plate 80, and there are openings for delivering the developer at both ends.

FIG. 4 is a diagram showing another embodiment of the present invention.
FIG. 5 is a diagram showing a temporal change in toner density at a certain position.
FIG. 6 is a schematic diagram for explaining the developer advection speed.
FIG. 7 is a view showing a modification of the partition plate.
In this example, an experiment was performed under the condition of a toner concentration of 7 wt% using a carrier having a volume average particle diameter of 35 μm and a toner having a particle diameter of 6 μm. First, a method for measuring the developer advection speed will be described. As shown in FIGS. 3 and 4, the developing device used in the experiment is provided with a plurality of toner concentration sensors 75 in the replenishing side stirring chamber and the developing side stirring chamber. When the time transition of each toner density sensor output when a certain amount of toner is replenished and agitated is examined, the time transition of toner density at a certain position is obtained as schematically shown in FIG. The advection speed of the velocity component (waveform peak position) is obtained. This is the average advection speed.
The average advection speed V2 when the developer makes one round in the developing device is obtained by dividing the transport path length by the time from the first round to the second round peak.
On the other hand, the advancing speed V1 of the transfer portion from the replenishing side stirring chamber to the developing side stirring chamber is determined by the toner concentration sensor provided in the downstream portion of the replenishing side stirring chamber and the toner concentration provided in the upstream portion of the developing side stirring chamber. It is determined from the time difference between the sensor waveform peaks and the distance between the sensors.
In this embodiment, the opening of the transfer section has a width of 32 mm × height of 26 mm, and a partition plate for the supply side stirring chamber and the development side stirring chamber is extended to the ceiling as shown in FIG. In the form, when the plate-shaped member was attached and the opening area was narrowed, the opening area was 185 mm ² . At this time, the local advection speed in the developing unit is as shown in FIG. 6. When the advection speed V1 / V2 was measured under these conditions, it was 0.62.

  A description will be given of the behavior of the developer at a position in front of the delivery section (a place where the developer is in a compacted state) under these conditions. If the opening area of the delivery part is reduced, the amount of developer that can pass through the delivery part is reduced, so that the developer contacts the ceiling lid of the supply side stirring chamber from about 1/3 of the downstream side of the supply side stirring chamber. It becomes a state to do. That is, the 360 ° developer is clogged around the screw. At this time, there are two concerns. One is a concern that if the replenished toner enters the compaction area without being completely dispersed, the developer is packed and transported as it is without being dispersed, and the other is that even if the screw rotates. There is a concern that a part of the developer (particularly the corner of the stirring chamber where the screw blades do not sweep) may form a non-moving layer and the developer may not circulate. When the developer is moved without moving the machine for a long period of time and the machine is moved, the developer will become non-uniform if the bulk density of the developer decreases and the developer that has been a non-moving layer moves. It causes density unevenness.

Since the developer does not pass visible light, the internal flow state cannot be observed with visible light. Therefore, it was decided to check the internal flow state using X-ray visualization technology.
The observation apparatus used is an X-ray transmission image observation apparatus H3150 manufactured by Toshiba IT Control. Further, as a tracer for grasping the behavior of the developer, 50 μm tungsten particles substantially equal to the carrier particle size were used. Tungsten has a higher absorption rate than the carrier (iron oxide) in the developer, so when observed with transmitted X-rays, only that portion is observed blacker than the surroundings. Further, since the tracer particles are sufficiently small, it is considered that the behavior of the developer is the same as that of the surrounding developer powder. Therefore, the developer behavior can be visualized by observing the flow state of tungsten. According to past experiments, it has been shown that in screw conveyance of powder, even if there is a difference of 20 times or more in density between the tracer particles and the powder particles, the behavior is almost the same.
A small amount of tracer was replenished with a spatula taking care not to disturb the flow of the field at the place where the developer behavior was observed. The developer stirring chamber was gently covered and installed in the apparatus, and the developer behavior when the screw was rotated was visualized by X-ray.
As a result, the tracer that has entered the consolidation area is dispersed in the same manner as in the non-consolidation area (agent level is slightly above the screw shaft) from the toner replenishment position of the replenishment side stirring chamber to the vicinity of the center of the replenishment side stirring chamber. I found out. Moreover, it was confirmed that the non-moving layer was not generated in the screw examined here.

FIG. 8 is a view showing a screw used in the example.
FIG. 9 is a diagram showing experimental results. FIG. 4A shows the result of the comparative example, and FIG. 4B shows the result of the present example.
The screw used in this example is a spiral screw having a pitch of 25 mm, an outer diameter of 20 mm, and an axial diameter of 8 mm, and is provided with a single plate-like member connected to the outer periphery of the screw blade in the longitudinal direction.
On the other hand, when using a screw whose outer diameter of the screw blade is thinner than the other part at the end downstream of the screw of the replenishment side stirring chamber as a comparative example, It was found that there was a slight immobile layer in the corner region formed by the side wall, and it was not suitable for the combination with the condition of actively using the consolidation region as in the present invention.
Next, a method for examining the charge rising property of the toner under the conditions of this embodiment will be described. 1 g of replenishment toner is replenished to the most upstream portion of the replenishment side stirring chamber. The screw is rotated at a predetermined speed, and the charge amount distribution of the developer immediately after the delivery portion is measured at the time when the peak of the replenished toner is transferred to the developing side stirring chamber. The result is shown in FIG. This graph shows a simple stirring device (replenishment side stirring chamber, developing side stirring chamber, screw, partition plate) by removing the developing roller and doctor blade from the developing device in order to show only the effect of the developer passage amount regulating means. , Only the developer passage amount regulating means). Compared with the result of FIG. 9A in which the developer passage amount regulating means is not used, the rising of the charge is clearly promoted, and it can be seen that the amount of uncharged toner is very small. In an actual developing device, rubbing by a doctor blade is also applied, so that this charging rise is sufficient. Next, this condition was carried out in an actual developing unit, and a printing test was conducted.
As a result, even under strict toner replenishment conditions (when developing solid images), the replenished toner is sufficiently dispersed and charged before reaching the development-side stirring chamber, and good image formation with no background contamination or toner scattering is achieved. Was done.

FIG. 10 is a diagram for explaining another embodiment of the present invention. FIG. 4A shows a state in which the opening is released, and FIG. 3B shows a state in which the opening is almost closed.
In this embodiment, a shutter member capable of controlling the cross-sectional area of the transfer portion opening of the replenishing side stirring chamber and the developing side stirring chamber is used as the developer passage amount regulating member. The shutter member is a plate-like member inserted downward from the ceiling of the delivery portion of the replenishment side stirring chamber and the development side stirring chamber, and the shutter member is driven up and down by a drive control means (not shown) to open the delivery portion. The area can be changed, and the rubbing force can be appropriately applied according to the charged state of the developer.
The developing device used in the present embodiment includes a toner density sensor (permeability sensor) and an image density sensor for detecting the image density of the reference toner image formed on the photoreceptor, and the toner density is a predetermined value. When it is detected that the image density of the reference toner image is lower than the predetermined level (that is, when the charge amount is small with respect to the toner density), the shutter member of the transfer unit is opened. Drive in a direction that reduces the partial area. When the shutter moves in the closing direction, the developer stays in the upstream portion in the transport direction with respect to the shutter, and the rubbing force of the developer increases. As a result, the rising of charging is promoted simultaneously with the promotion of the dispersion of the replenishing toner. After the charge has risen sufficiently, or when the image forming process continues with little image area ratio and almost no toner replenishment, it is not necessary to raise the charge amount any further. It is driven to increase the area so that unnecessary stress is not applied to the developer.

When such an opening area control is performed, as a result of the investigations by the inventors, the average advection speed V2 at which the developer makes one round in the developing device and the downstream side end of the replenishing side stirring chamber receive the developing side stirring chamber. Between the advection velocity V1 immediately after being passed,
0.6 <V1 / V2 <1
If the control is performed so that the above relationship is satisfied, there is no problem that the stress is too strong and the deterioration of the developer is accelerated, and the developer in the developing side agitating chamber is insufficient, so that a good pumping is not caused. Was done.
V1 / V2 <0.6 is not appropriate because the stress applied to the agent becomes excessive, causing an increase in the stirring torque of the developing device and the deterioration of the toner. On the other hand, when V1 / V2> 1, the agent level at other locations is relatively high instead of no longer staying in front of the delivery unit. For example, when the agent level is high at the toner replenishment position, the replenishment toner is contained in the developer. Is not taken in well, resulting in a problem that the dispersibility deteriorates.

FIG. 11 is a view for explaining still another embodiment of the present invention.
In this embodiment, the same developing unit as that of Example 2 is used except for the transfer section, and the shutter member is a plate-like member protruding toward the ceiling from the bottom surface of the transfer section of the supply side stirring chamber and the development side stirring chamber, The opening member area is changed by moving the shutter member up and down by a drive control means (not shown).
With the configuration of this example, it was possible to perform good image formation without toner scattering and background stains.

FIG. 12 is a view for explaining still another embodiment of the present invention.
In this embodiment, the same developing device as that in Example 2 is used, and the shutter member is a plate member that can slide in the lateral direction between the supply side stirring chamber and the transfer side stirring chamber. The opening area is changed by moving left and right by a drive control means (not shown).
With the configuration of this example, it was possible to perform good image formation without toner scattering and background stains.

FIG. 13 is a view for explaining still another embodiment of the present invention.
In this embodiment, the same developing device as that of the second embodiment is used except for the transfer section, and the shutter member is a plurality of parallel plates such as blinds provided in the transfer section of the supply side stirring chamber and the development side stirring chamber. It is composed of members, and the sectional area of the opening is changed by changing the angle in the same direction by interlocking the individual shutter members with a drive control means (not shown). At this time, a plate-like member having a sufficiently small width is used so as not to interfere with the screw blades even when the plate-like member of each shutter is horizontal. In this example, a member having a width of 4 mm was used.
With the configuration of this example, it was possible to perform good image formation without toner scattering and background stains.

1 is an internal configuration diagram of a color image forming apparatus to which a developing device according to an embodiment of the present invention is applied. It is a figure which shows one Embodiment of the image development apparatus used for the said image forming apparatus. It is longitudinal direction sectional drawing of a developing device. It is a figure which shows other embodiment of this invention. It is a figure which shows the time change of the toner density in a certain position. It is a schematic diagram for demonstrating the advection speed of a developing agent. It is a figure which shows the modification of a partition plate. It is a figure which shows the screw used for the Example. It is a figure which shows an experimental result. It is a figure for demonstrating the other Example of this invention. It is a figure for demonstrating the further another Example of this invention. It is a figure for demonstrating the further another Example of this invention. It is a figure for demonstrating the further another Example of this invention.

Explanation of symbols

66, 67 Agitating screw 75 Toner density sensor 78 Developer passage amount regulating member 80 Partition plate 86 Supply side agitating chamber 87 Developing side agitating chamber

Claims (6)

Agitating means that agitates and disperses two-component developer consisting of toner and carrier with two rotatable screws disposed in the developer container and conveys it to a predetermined position, and replenishes toner consumed by development And a toner replenishing means for developing, a toner density detecting means for the developer, and an image density detecting means for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. In the device
When the developer container on the side where the toner is replenished is the replenishment side stirring chamber and the developer container on the side facing the developer carrier is the development side stirring chamber, the developer transport in the replenishment side stirring chamber A developer passage amount regulating member that changes an area of the opening at the opening that delivers the developer from the downstream end in the direction to the developing side stirring chamber;
The developer passage amount regulating member is composed of a shutter member capable of changing a cross-sectional area of a transfer portion of the replenishing side stirring chamber and the developing side stirring chamber.
The shutter member is a plate-like member inserted downward from the ceiling of the delivery unit, and the opening member area is changed by moving the plate-like member up and down,
When the toner density detecting means detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting means detects that the image density of the reference toner image is lower than a predetermined level, A developing device characterized in that a developer passage amount regulating member is actuated to reduce the area of the opening so as to retain the developer upstream of the opening in the developer transport direction. Agitating means that agitates and disperses two-component developer consisting of toner and carrier with two rotatable screws disposed in the developer container and conveys it to a predetermined position, and replenishes toner consumed by development And a toner replenishing means for developing, a toner density detecting means for the developer, and an image density detecting means for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. In the device
When the developer container on the side where the toner is replenished is the replenishment side stirring chamber and the developer container on the side facing the developer carrier is the development side stirring chamber, the developer transport in the replenishment side stirring chamber A developer passage amount regulating member that changes an area of the opening at the opening that delivers the developer from the downstream end in the direction to the developing side stirring chamber;
The developer passage amount regulating member is composed of a shutter member capable of changing a cross-sectional area of a transfer portion of the replenishing side stirring chamber and the developing side stirring chamber.
The shutter member is a plate-like member that is slidable in the lateral direction through the opening of the delivery unit, and the opening member area is changed by moving the plate-like member left and right.
When the toner density detecting means detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting means detects that the image density of the reference toner image is lower than a predetermined level, A developing device characterized in that a developer passage amount regulating member is actuated to reduce the area of the opening so as to retain the developer upstream of the opening in the developer transport direction . Agitating means that agitates and disperses two-component developer consisting of toner and carrier with two rotatable screws disposed in the developer container and conveys it to a predetermined position, and replenishes toner consumed by development And a toner replenishing means for developing, a toner density detecting means for the developer, and an image density detecting means for detecting the image density of the reference toner image formed on the surface of the image carrier on which the electrostatic latent image is formed. In the device
When the developer container on the side where the toner is replenished is the replenishment side stirring chamber and the developer container on the side facing the developer carrier is the development side stirring chamber, the developer transport in the replenishment side stirring chamber A developer passage amount regulating member that changes an area of the opening at the opening that delivers the developer from the downstream end in the direction to the developing side stirring chamber;
The developer passage amount regulating member is composed of a shutter member capable of changing a cross-sectional area of a transfer portion of the replenishing side stirring chamber and the developing side stirring chamber.
The shutter member is a plurality of parallel plate-like members provided in the delivery unit, and the plate-like member is configured to change the opening area by changing the angle,
When the toner density detecting means detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting means detects that the image density of the reference toner image is lower than a predetermined level, A developing device characterized in that a developer passage amount regulating member is actuated to reduce the area of the opening so as to retain the developer upstream of the opening in the developer transport direction . The developing device according to any one of claims 1 to 3,
When the toner density detecting means detects that the toner density of the developer is equal to or higher than a predetermined value, and the image density detecting means detects that the image density of the reference toner image is lower than a predetermined level, The advection speed V1 from the downstream end of the replenishment side stirring chamber to immediately after it is transferred to the development side stirring chamber, and the average advection speed V2 at which the developer recirculates once in the developing device,
0.6 <V1 / V2 <1
The developing device, wherein the developer passage amount regulating member is operated so as to satisfy the relationship . 5. A process cartridge comprising: at least two of a latent image carrier, a charging device, and a latent image carrier cleaning device, and the developing device according to claim 1 . An image forming apparatus comprising the developing device according to claim 1, wherein an image formed by a series of image forming processes is recorded on a recording medium .

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