JP3524312B2 - Rotary developing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary developing device used in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and the like, and more specifically, to a plurality of two-component developers containing toners of respective colors and carriers. a developing unit, a rotary current <br/> image for visualizing a latent formed latent image bearing member is moved to a developing position facing any of the developer to the latent image bearing member It relates to the device.

[0002]

2. Description of the Related Art Heretofore, it has been known that a developing device of this type is provided with a toner replenishing means to replenish the consumed toner in a two-component developer to maintain a constant toner density. ing.

As a developing device provided with the toner replenishing means, for example, in Japanese Patent Laid-Open No. 62-182768, a toner replenishing port is provided for each of a plurality of toner chambers, and the toner is replenished to the outside of the developing device through the toner replenishing port. A rotary multicolor developing device for replenishing toner into a toner chamber from a toner container provided is disclosed.

Further, Japanese Unexamined Patent Publication No. 60-257459 and Japanese Utility Model Laid-Open No. 61-76445 disclose a developing device in which a toner container is provided in the developing device and toner is supplied from the toner container to the developing device. Has been done.

[0005]

However, in JP-A-62-182768, the position where the toner can be replenished to each toner chamber is either the developing position or the retreat position. It is necessary to stop the toner replenishing operation even if the toner replenishing amount does not reach the predetermined amount due to the replacement of the developing device located at the developing position. Therefore, in the next step, there arises a problem that the image density of the corresponding color is reduced and color unevenness occurs. In particular, when the toner is replenished at the retracted position, there arises a problem that the image density is lowered during continuous copying of a single color image or during solid image formation.

If the interval for replacing the developing devices is set long so as not to stop the toner replenishing operation, there arises a problem that useless downtime occurs.

Further, the above-mentioned JP-A-60-257459,
In Japanese Utility Model Laid-Open No. 61-76445, since the toner container corresponding to each developing device is built in the developing device, there is a problem that the device becomes large and the cost increases.

When the developing device is downsized in order to avoid an increase in the size of the apparatus, the amount of the internal developer is also reduced, so that the toner density balance is destroyed in a short time during continuous copying of a single color image or solid image formation. There is a problem that the image density tends to decrease.

The present invention has been made in view of the above problems, and a first object thereof is to avoid a wasteful downtime and an increase in size of the apparatus, resulting in insufficient toner supply. It is an object of the present invention to provide a developing device capable of preventing a decrease in image density and color unevenness.

Further, the above-mentioned JP-A-62-182768,
JP-A-60-257459, JP-A-61-76445
In the publication, since it is desired to consider the stirring time of the developer after the toner is replenished, there is also a problem that the background stain and the uneven density occur due to insufficient triboelectric charging of the developer and uneven toner concentration distribution due to insufficient stirring. .

If the agitation time is set to be long in advance so as to prevent insufficient triboelectric charging of the developer and uneven toner concentration distribution, there arises a problem that useless downtime occurs.

The present invention has been made in view of the above problems, and a second object thereof is that the developer is not sufficiently stirred after the toner is replenished without causing unnecessary downtime. It is an object of the present invention to provide a developing device capable of preventing background dirt and density unevenness.

[0013]

In order to achieve the first object, the invention of claim 1 has a plurality of developing devices containing a two-component developer consisting of toner of each color and a carrier,
The rotary type developing device for visualizing a latent formed is moved to a developing position facing the latent image carrier latent image bearing member of any of the developer by rotation thereof, and the developing position < It is characterized in that a toner replenishing means capable of replenishing toner into the developing device is provided at both the retracted position retracted from the developing position.

In the rotary developing device according to the first aspect, the toner can be replenished into the developing device by the toner replenishing means at the developing position and the retreat position. Therefore, even if the amount of toner replenished to the developing device at the developing position does not reach the predetermined amount when the developing device located at the developing position is replaced, the toner replenishing operation does not stop with the replacement of the developing device and is retracted. Toner is supplied to the developing device until a predetermined amount is reached at the position. Further, during continuous copying of a single color image or during solid image formation, toner is supplied to the developing device until the toner supply amount reaches a predetermined amount at the developing position.

The predetermined amount of toner replenishment is a fixed amount replenishment system in which the standard toner consumption amount calculated based on the standard image original is replenished at regular intervals (constant copy intervals).

The invention of claim 2 is the rotation of claim 1.
The mold developing device is provided with a density detecting means for detecting the toner density of the two-component developer in the developing device. If the detection value detected by the density detecting means does not reach the predetermined value, the predetermined value is reached. It is characterized in that the toner is replenished by the toner replenishing means until it reaches.

In the rotary developing device according to the present invention, the toner density in the two-component developer in the developing device is detected by the density detecting means, and when the detected value does not reach the predetermined value, the predetermined value is reached. The toner is replenished by the toner replenishing means until reaching. For example, when the developing device located at the developing position does not reach the predetermined value of the toner density when the developing device is replaced, toner is replenished at the retracted position until the detected value reaches the predetermined value. That is, the toner is replenished based on the detection value of the density detecting means.

In order to achieve the second object, the invention of claim 3 is the rotary developing device according to claim 1 or 2, wherein the two-component developer in the developing device is located at the developing position and the retreat position. A stirring means capable of stirring is provided, and when toner is replenished by the toner replenishing means, the stirring of the agent by the stirring means is continued until a predetermined time is reached.

[0019]

In the rotary developing device according to the third aspect , the two-component developer in the developing device can be agitated by the agitating means at the developing position and the retreat position, and the toner is replenished by the toner replenishing means. In this case, the stirring of the agent by the stirring means is continued until a predetermined time is reached. For example, at the time of replacing the developing device, even if the agent stirring time by the stirring means at the developing position has not reached the predetermined time, the stirring is performed at the retracted position until the predetermined time is reached. Even if toner is replenished to the developing device located at the developing position immediately before replacement of the developing device, stirring is continued until the predetermined time is reached at the retracted position. Therefore, insufficient triboelectric charging of the developer and uneven toner concentration distribution will not occur due to insufficient stirring of the developer.

In order to achieve the above first or second object,
According to a fourth aspect of the present invention, in the rotary developing device according to the third aspect , the agent stirring speed by the stirring means is lower at the retracted position than at the developing position.

In the rotary developing device according to the fourth aspect, the agent stirring speed by the stirring means is lower at the retracted position than at the developing position. Here, in order to obtain good image reproducibility, the relative speed between the latent image bearing member and the developer bearing member carrying the developer supplied to the latent image bearing member at the time of development is high. Is desirable, and in order to reduce the fluid resistance because there is no retention in the developer flow of the developer in the developing device,
It is desirable that the linear velocities of the developer carrying member and the stirring means are similar. On the other hand, except during development, in order to reduce the occurrence of toner and carrier scattering and the spent formation in which the toner melts due to frictional heat and adheres to the carrier, it is desirable to slow the agent stirring speed by the stirring means.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a developing device used in a color electrophotographic printer (hereinafter referred to as a printer) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. First, an outline of the entire printer will be described. In FIG. 1, a photosensitive drum 1 as a latent image carrier
Is rotationally driven in the direction of arrow A, is uniformly charged by a charging charger 2 as a uniform charging means, and is then scanned and exposed based on image information by a laser optical device 3 to form an electrostatic latent image on the surface. To be done. Here, the image information to be exposed is image information of a single color obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black.
The electrostatic latent image formed on the photoconductor drum 1 is developed by the rotary developing device 4 described later with yellow, magenta, cyan, and black toners as predetermined developers, respectively. An image of each color is formed on.

Each color image formed on the photoconductor drum 1 is formed on the intermediate transfer belt 5 which rotates in the direction of arrow B in the figure in synchronization with the photoconductor drum 1 for each single color of yellow, magenta, cyan and black. The primary transfer charger 6 sequentially performs the superimposed transfer. The images of yellow, magenta, cyan, and black superposed on the intermediate transfer belt 5 are transferred from the automatic paper feed cassette 7 for double-sided copying or the manual paper feed tray 7a through the paper feed rollers 8 and 8a and the registration rollers 9 to the transfer unit. The secondary transfer charger 11 collectively transfers the transferred sheet 10 onto the transfer sheet 10. After the transfer is completed, the toner image is fixed on the transfer paper 10 by the fixing device 12, and the transfer paper 10 is discharged outside the machine as a full color print.

The toner on the photoconductor drum 1 that has not been transferred onto the intermediate transfer belt 5 is removed by the photoconductor cleaner 13.
Is removed from the photosensitive drum 1 by the
The toner on the intermediate transfer belt 5 that has not been transferred onto the
It is removed from the intermediate transfer belt 5 by the intermediate transfer belt cleaner 14.

FIG. 2 is a front view showing a schematic structure of the rotary developing device 4. In this rotary developing device 4, casing parts 21Y, M, C, 21 which are divided into developing units dedicated to the respective colors of yellow, magenta, cyan, and black in a cylindrical developing drum 20 made of aluminum are integrated. It is a composition. Each developing unit contains a carrier as a developer and a two-component developer (hereinafter referred to as a developer) including toner of each color. In the illustrated example, a developing unit of a black developing device containing black toner and a carrier is located at a developing position facing the photoconductor drum 1, and a yellow developing device containing yellow toner and a carrier is arranged in a counterclockwise order in the drawing. Developing unit, a magenta developing unit containing magenta toner and a carrier, and a cyan developing unit containing cyan toner and a carrier.

The rotary developing device 4 has a rotary shaft 2
It is rotatably attached to the printer main body around 2. By the rotation of the rotating shaft 22, the developing unit is switched between the developing position and the retracted position retracted from the developing position.

Since the internal structure of each of the four developing units is exactly the same, the internal structure will be described below by taking the black developing unit located at the developing position as an example, and the internal structures of other developing units will be described. As the reference numerals of the members to be used, the same reference numerals as the reference numerals in the black developing unit and the suffixes Y, M, and C for distinguishing the developing units of yellow, magenta, and cyan are shown in the drawings, and the description thereof will be omitted.

In the casing 21 of the black developing unit, a developing sleeve 23 as a developer carrying member for carrying a developer on the surface and supplying it to the photosensitive drum 1, and a stirring rotor 24 as the stirring means. A conveying brush 25 that conveys the toner replenished from the toner replenishing means described later toward the upstream side in the developer conveying direction, that is, toward the stirring rotor 24 side.
And a toner concentration sensor 26 as the concentration detecting means.
A doctor 27 that regulates the layer thickness of the developer on the developing sleeve 23; and a separator 28 that scrapes off the developer layer on the developing sleeve 23 that has passed through the developing area.

The developing sleeve 23 is composed of a sleeve made of a non-magnetic material (for example, aluminum) and a magnet arranged in the sleeve. The developing sleeve 23 is disposed so that a part thereof is exposed from the slit formed in the developing drum 20 toward the photosensitive drum 1.

As shown in FIG. 3 (a), the stirring rotor 24 is composed of a rotating shaft 24a and a blade portion 24b extending radially from the rotating shaft. This stirring rotor 2
4 operates by driving a dedicated stirring rotor drive motor 29 provided at the end of the rotary shaft 24a based on a drive signal from the CPU. The material is non-magnetic aluminum or stainless steel. Further, instead of the stirring rotor 24, a stirring screw shown in FIG.
The transport brush 25 is made of resin or metal.

FIG. 4 is an enlarged view of the vicinity of the black developing unit located at the developing position. Further, in the figure, arrows indicate the flow of the developer in the casing portion 20 of the black developing unit. The developer in the casing 20 is conveyed to the developing sleeve 23 side while being stirred by the stirring rotor 24, and is supplied onto the developing sleeve. After the layer thickness of the developer on the developing sleeve 23 is regulated by the doctor 27, the developer is conveyed to the developing area to visualize the latent image on the photosensitive drum 1. Then, the developer on the developing sleeve 23 that has passed through the developing area is scraped off at the end portion of the separator 28 and moves the inclined portion of the separator toward the stirring rotor 24 side, but a part thereof is the inclined portion. A toner concentration sensor 26 provided in the center of the center bobbin 26a flows into the center bobbin 26a, and the toner concentration is detected.

In the figure, reference numeral 33 is a developing unit switching motor, and 34 is a developing sleeve rotating motor.

Here, the toner density control, which is a feature of this embodiment, will be described. As shown in FIGS. 2 and 5, the toner replenishing means according to the present exemplary embodiment is disposed outside the rotary developing device 4 to replenish toner to the black, yellow, magenta, and cyan developing units at the developing position. The first toner supply pipes 31, 31Y, M, and C that are made possible by the above, and the second toner supply pipes 32, 32Y that are made possible at the retracted position,
M and C are provided in parallel in the axial direction of the developing drum 20. To correspond to the first and second toner supply pipes,
The developing drum 20 has toner replenishing ports 30, 30Y,
M and C are formed. The toner supply port is
It can be opened and closed by an automatic shutter.

The first and second toner supply pipes 31, 32
Has the first and second toner supply coils 31a and 32 inside.aTo
I have it. At the end of the first and second toner supply coils,
The 1 and 2 toner supply motors 31b and 32b are directly connected.
It Incidentally, the first and second toner supply coils 31a, 32a
Is a piano wire with a wire diameter of about 1.5 mm, between the coils
The distance is 5 to 10 mm. In addition, wind a spiral piece around the shaft.
The shape may be tight.

The first and second toner supply pipes 3 are also provided.
1, 32 have first and second guide sleeves 31c, 3 at the end portions.
2c. The first and second guide sleeves 31
c and 32c are expandable / contractible in the direction of the arrow in FIG. 2 and are located at the avoiding position for avoiding contact with the developing drum 20 except when toner is being replenished. When toner is replenished, toner can be replenished to the developing unit. Move to position. As a telescopic mechanism, a tension spring is screwed into the first and second toner supply pipes 31 and 32 at one end above the guide sleeves 31c and 32c, and the other end is attached to a spring anchor integrated with the supply pipe. Cover, normal development drum 20
The force may be applied in a direction away from the developing drum 20, and the toner may be pushed out toward the developing drum 20 side by a solenoid when replenishing the toner. Also, without providing a guide sleeve,
The entire supply pipe may be expanded and contracted by a lever via a solenoid. Further, instead of moving to the replenishing position when replenishing toner, it may be configured to move to the avoiding position only when the developing drum 20 rotates so that a toner replenishing signal can be immediately responded.

The toner density sensor 26 includes a center bobbin 26a and a center bobbin 2 as shown in FIG.
6a and a coil 26b wound around the outer circumference. The density detecting means according to the present embodiment utilizes the fact that the inductance value changes according to the amount of iron powder (carrier) of the developer passing through the center bobbin 26a (for example, Japanese Patent Publication No. 60-2662). (See Japanese Patent Publication). The toner replenishment is controlled by reading the change in the inductance value and controlling the drive signals of the first and second toner replenishing motors 31b and 32b by a toner density control unit (not shown). (Hereafter, margin)

FIG. 6 is a block diagram of the controller, and FIG. 7 is a flow chart for explaining the toner replenishment and agitation operations. First, when the development unit switching operation completion detection sensor detects that the development unit of the corresponding color is located at the development position (step 1), the toner concentration of the developer is a predetermined concentration based on the detection value of the toner concentration sensor 26. It is determined whether it is lower (step 2). Here, when it is determined that the toner concentration of the developer is lower than the predetermined concentration, the toner is replenished at the developing position and the stirring rotor 24 is used.
The agent stirring operation is performed (steps 3 and 4). On the other hand, when it is determined that the toner concentration of the developer has reached the predetermined concentration, the developing unit switching operation is executed by the rotation of the rotating shaft 22 when the developing unit switching signal is transmitted (step 2a). 2b).

The above toner replenishing operation is continued until the toner density of the developer reaches a predetermined density (step 5,
6). During this period, the presence or absence of the transmission of the developing unit switching signal is detected (step 7). When the transmission of the signal is detected, the toner replenishment and the agent stirring operation are interrupted (step 8), and the developing unit switching operation is executed. (Step 9). When the completion of the developing unit switching operation is detected (step 10), the toner replenishment and stirring operation at the retracted position for the developing unit of the corresponding color is executed (step 1).
1). Then, the toner replenishing operation is continued until the toner density of the developer reaches a predetermined density, and is stopped when the predetermined density is reached (steps 12 and 13). On the other hand, regarding the agent stirring operation, the agent stirring time sensor detects whether the agent stirring time has reached a predetermined time (step 1
4) If it is detected that the agent stirring time has reached the predetermined time, the agent stirring operation is stopped (step 15). On the other hand, when it is detected that the agent stirring time has not reached the predetermined time, the agent stirring operation is continued (step 16).

When the transmission of the developing unit switching signal is detected while the agent stirring operation of step 16 is continued (step 21), the agent stirring operation is interrupted (step 22) and the developing unit switching operation is executed (step 21). 23). When the completion of the developing unit switching operation is detected (step 24),
The stirring operation at the retracted position for the developing unit of the corresponding color is executed (step 25). Then, the agent stirring operation is continued until the agent stirring time reaches a predetermined time, and is stopped when the predetermined time is reached (steps 26 and 27).

When it is determined in step 5 that the toner density of the developer has reached the predetermined density, the toner replenishing operation is stopped (step 17). Then, the agent stirring operation is stopped when the agent stirring time reaches a predetermined time (steps 18 and 19). In step 18, when it is determined that the agent stirring time has not reached the predetermined time, the agent stirring operation is controlled according to the steps 21 to 27 described above.

FIG. 8 is a flow chart for explaining the agent stirring operation when the toner replenishing operation is executed only at the developing position. When the execution of the toner replenishing operation at the developing position is detected, the agent agitating operation is executed at the same position (step 1,
2). The agent stirring operation is stopped when the agent stirring time reaches a predetermined time (steps 3 and 4). In step 3, when it is determined that the agent stirring time has not reached the predetermined time, the agent stirring operation is controlled in accordance with the steps 21 to 27 described above.

It should be noted that FIG. 8 is not limited to the developing device of the present embodiment equipped with toner replenishing means capable of replenishing toner at the developing position and the retreat position, but a toner replenishing means capable of replenishing toner only at the developing position. It is applicable to control of the agent stirring operation in the provided developing device.

FIG. 9 is a chart showing the timing of the developing unit switching operation in the full color mode, FIG.
FIGS. 0A and 0B are charts showing timings of toner replenishment and agent agitation operations with respect to the developing unit switching operation. The developing unit switching operation is a developing unit switching signal a that is transmitted every time the copying speed (sheets / minute) is divided by the number of colors, regardless of the toner replenishment and agent agitating operations.
According to. In the figure, b is the developing unit switching operation time, c is the visualization processing step time at the developing position, and d1 to d3.
Indicates the waiting time at the retracted position. In the monochromatic mode, the developing process is continuously performed while the corresponding developing unit is fixed at the developing position.

As shown in FIG. 10A, the agent agitating operation is executed at the start of toner replenishment, and the agent is replenished for a predetermined time l1 with respect to the first toner replenishment time s1 at the developing position to the corresponding developing unit. The stirring operation is executed at the developing position. Further, for the second toner replenishment time s2 at the developing position to the developing unit, the agent stirring operation for a predetermined time (l2 + l3) is executed at the developing position until the developing unit switching operation starts, and the shortage is evacuated. Run with. In addition, FIG.
As shown in (b), the first toner replenishment time s3 at the developing position to the corresponding developing unit and 2 at the retreat position.
A predetermined time (l4 +
The agent stirring operation of 15) is executed at the developing position until the developing unit switching operation starts, and the shortage is executed at the retracted position.

The execution time of the agent agitation operation differs depending on the unit conditions such as the developer weight with respect to the toner replenishment amount and the agitation efficiency. Further, it is not always necessary to interrupt the agent stirring operation during the developing unit switching operation (the same applies to FIGS. 7 and 8). In the present embodiment, as indicated by the shaded area in the figure, the drive of the stirring rotor 24 is continued for the purpose of circulating the developer regardless of toner supply.

FIG. 11 is a chart for explaining the control of the agent stirring speed for the developing unit switching operation. Considering the life of the developer and the generation of toner and carrier scattering, it is desirable that the stirring speed of the stirring rotor 24 is low. However, at the time of the visualization processing, the higher the relative speed of the developing sleeve 23 with respect to the photosensitive drum 1, the better the image reproducibility. Further, it is desirable that the linear velocities of the developing sleeve 23 and the agitating rotor 24 be approximated to each other in order to reduce the fluid resistance without the retention of the agent flow in the casing portion. Therefore, in the present embodiment, the stirring speed by the developer rotor 26 at the retracted position is set to be low with respect to the developing position.

As described above, in this embodiment, the toner can be replenished by the toner replenishing means into the developing unit at the developing position and the retreat position, and the developer in the developing unit at the developing position when the developing unit is switched. Even if the toner density is at the predetermined density, the toner can be replenished until the predetermined density is reached at the retracted position after the developing unit switching operation is completed. Therefore, the toner density of the developer is kept constant, and it is possible to prevent a decrease in image density and color unevenness. Further, even when a large amount of toner is consumed during continuous copying of a single-color image or solid image formation, toner can be replenished until the toner density of the developer reaches a predetermined density at the developing position. Therefore, the toner density of the developer is maintained constant even during continuous copying of a single-color image or solid image formation, and the decrease in image density can be prevented.

Further, in this embodiment, since the toner replenishing means is not built in the rotary type developing device 4, it is possible to avoid the enlargement of the device.

Further, in the present embodiment, agent stirring by the stirring rotor 24 is possible at the developing position and the retracted position, and the agent stirring time of the developer in the developing unit at the developing position at the developing position is changed to a predetermined time. Even if it has not reached, the agent can be stirred at the retracted position until the predetermined time is reached. Therefore, insufficient triboelectricity of the developer and uneven toner concentration distribution do not occur due to insufficient stirring of the developer, so that it is possible to prevent background stains and uneven density.

Further, in this embodiment, since a copying sequence can be obtained regardless of the toner replenishment time and the agent stirring time, it is possible to prevent wasteful downtime and improve the productivity.

Further, in the present embodiment, since the agent stirring speed by the stirring rotor 24 is set to be lower at the retracted position than at the developing position, the toner is melted by frictional heat and fixed to the carrier. The spent can be reduced. Therefore, the life of the developer can be extended. In addition, toner and carrier scattering from the gap between the casing and the developing sleeve can be reduced.

[0053]

According to the first aspect of the invention, when the developing device located at the developing position is replaced, even if the amount of toner supplied to the developing device at the developing position does not reach the predetermined amount, the developing device is replaced. Along with this, the toner replenishment operation is not stopped and toner is replenished to the developing device until the predetermined amount is reached at the retracted position.
Therefore, it is possible to prevent a decrease in image density and color unevenness, obtain a copy sequence irrespective of the toner replenishment time, and realize an image formation with high productivity without wasteful downtime. effective. Further, during continuous copying of a single-color image or during solid image formation, toner is replenished to the developing device until the toner replenishment amount reaches a predetermined amount at the developing position, so that there is an excellent effect that reduction in image density can be prevented. . Also, the toner container
Since it is not built in the rotary developing device, there is an excellent effect that the size of the device can be avoided. In addition, in claim 2
According to the invention, the toner is detected based on the detection value of the density detecting means.
When toner is replenished by the fixed amount replenishment method in order to replenish
Compared to, it is possible to maintain an appropriate toner density.
effective. Further, according to the invention of claim 3,
Insufficient agitation causes insufficient triboelectricity of developer and toner concentration distribution
Since unevenness does not occur, background stains and uneven density are generated.
It has an excellent effect of being able to prevent life. Also, the claims
According to the invention of 4, the agent stirring speed by the stirring means is
It is slower in the retracted position than in the position. Therefore, image reproduction
Toner and carrier scattering without deteriorating
In addition to reducing the amount of raw material, the toner melts due to frictional heat.
Longer life of developer because it can reduce spent to stick to carrier
It has an excellent effect that it can be destined.

[0054]

[0055]

[0056]

[Brief description of drawings]

FIG. 1 is a front view showing a schematic configuration of a printer according to an embodiment.

FIG. 2 is a front view showing a schematic configuration of the rotary developing device in FIG.

FIG. 3A is a perspective view of a stirring rotor. (B) is a perspective view of a stirring screw.

FIG. 4 is an enlarged view near a black developing unit located at a developing position.

FIG. 5 is a perspective view of the rotary developing device.

FIG. 6 is a block diagram of a control unit.

FIG. 7 is a flowchart illustrating toner replenishment and agitation operations according to the present embodiment.

FIG. 8 is a flowchart illustrating a stirring operation when a toner replenishing operation is executed only at a developing position.

FIG. 9 is a chart showing the timing of the developing unit switching operation in the full color mode.

10A and 10B are charts showing timings of toner replenishment and agitation operations with respect to the developing unit switching operation.

FIG. 11 is a chart illustrating the control of the agent stirring speed with respect to the developing unit switching operation.

[Explanation of symbols]

1 photoconductor drum 2 Charger 3 Laser optical device 4 Rotating developing device 5 Intermediate transfer belt 6 Primary transfer charger 7 Automatic paper cassette for double-sided copying 7a Manual feed tray 8,8a Paper feed roller 9 Registration roller 10 Transfer paper 11 Secondary transfer charger 12 Fixing device 13 Photoconductor cleaner 14 Intermediate transfer belt cleaner 20 development drum 21, 21Y, M, C Casing part 22 rotation axis 23, 23Y, M, C Development sleeve 24, 24Y, M, C Stirring rotor 25, 25Y, M, C Conveyor brush 26, 26Y, M, C density sensor 27, 27Y, M, C Doctor 28, 28Y, M, C separator 29 Agitation rotor drive motor 30, 30Y, M, C Toner supply port 31, 31Y, M, C First toner supply pipe 32, 32Y, M, C Second toner supply pipe 31a, 32a First and second toner supply coils 31b, 32b First and second supply motors 31c, 32c First and second guide sleeves 33 Development unit switching motor 34 Developing sleeve rotation motor

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/08

Claims (4)

(57) [Claims] 1. A plurality of developing devices each containing a two-component developer composed of toner of each color and a carrier, and by rotation thereof, an arbitrary developing device is placed at a developing position facing a latent image carrier. rotating for visualizing a latent formed latent image bearing member and the moved
In type developing device, both a retracted position retracted from the developing position and the developing position
A rotary developing device characterized by comprising a toner replenishing means capable of replenishing the toner in the developing device at one position . 2. The rotary developing device according to claim 1, further comprising density detecting means for detecting the toner density of the two-component developer in the developing device, and the detection value detected by the density detecting means is a predetermined value. for unreached, rotary type developing device which is characterized in that the toner supply by the toner replenishing means until it reaches the predetermined value. 3. The rotary developing device according to claim 1, further comprising a stirring means capable of stirring the two-component developer in the developing device at the developing position and the retracted position, and the toner replenishing means replenishes the toner. The rotating developing device is characterized in that the stirring of the agent by the stirring means is continued until a predetermined time is reached. 4. The rotary developing device according to claim 3, wherein the agent stirring speed by the stirring means is higher than that at the developing position.
The rotary type is characterized by low speed at the above retracted position.
Image device.