JPH048790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention comprises a plurality of developing units, and each developing unit is moved to a developing position for developing a latent image formed on an image carrier by a supporting means. The present invention relates to an image forming apparatus configured to be able to circulate and move, and can be suitably implemented in, for example, a color electrophotographic copying machine, and a color recording apparatus that constitutes an output section of a computer, a facsimile, and the like.

The image forming apparatus according to the present invention can only use a rotary developing device in which the supporting means for supporting and conveying a plurality of developing units is a rotating body and each developing unit moves along a circular orbit. Instead, it is also possible to use a developing device in which the supporting means is an endless circulating body other than a rotating body and each developing unit moves along a non-circular orbit such as an elliptical orbit.

Furthermore, when the image forming apparatus according to the present invention is embodied in a color electrophotographic copying machine, a color recording device, etc., these devices are not limited to full color, but can also be used for two or more monochrome colors, The image forming apparatus may be a so-called multi-color image forming apparatus, and the image bearing member of the image forming apparatus is not limited to an electrophotographic photoreceptor, but may be any other latent image bearing member such as an insulator carrying a latent image. .

BACKGROUND OF THE INVENTION Recently, the demand for color copying has increased rapidly not only in specialized fields but also in general office work, and a color copying machine that can be used not only by professionals but also by anyone is desired. Currently, full-color electrophotographic copying machines that utilize electrophotographic technology are generally widely used as color copying machines.

Full-color electrophotographic copying machines still have various problems that need to be solved or improved, but one of them is the ability to visualize each color electrostatic latent image formed on the image carrier, that is, the photoreceptor. There is a developing device that uses toner or developer in any configuration, that is,
There is a problem in replenishing each developing unit.

Conventionally, various color electrophotographic copying machines have been proposed, but the developing devices used can be roughly divided into two types. One of them is a side-by-side developing device in which a plurality of developing units each having a developer of each color are arranged in parallel along the surface of a photoreceptor, and the other is, for example, disclosed in Japanese Patent Application Laid-Open No. 131-1981. As disclosed in , this is a so-called rotary developing device in which a rotating wheel is provided adjacent to a photoreceptor and a plurality of developing units are arranged around the wheel.

The above-mentioned side-by-side developing device seems to have a simple structure, since it is only necessary to sequentially arrange a plurality of developing units having developers of different colors around the cylindrical photosensitive drum. In reality, it is necessary to keep the other developing units inactive while one developing unit is in operation, and for this purpose, the rotation of the magnetic brush roller in the developing unit must be controlled or the developing units It is necessary to take measures such as moving the photosensitive drum itself away from the surface of the photosensitive drum.
In the end, the side-by-side developing device is also forced to have a complicated structure and complicated operation control.

Furthermore, according to this type of developing device, since a plurality of developing units are sequentially arranged around the photosensitive drum, the diameter of the photosensitive drum inevitably becomes large, which makes it difficult to downsize the electrophotographic copying machine. It is extremely difficult. Furthermore, although the position where the latent image of each color is formed on the photosensitive drum is constant, the developing position of each color by the developing unit is different, and therefore the time required for the latent image of each color to be developed is different. Correction of the time decay of the latent image is required. Such correction work is not technically simple and complicates the control of the developing device and the copying machine as a whole.

On the other hand, rotary developing devices carry out development by placing only the developing unit of the desired color in opposition to the latent image on the photosensitive drum. It has the advantage that it can be miniaturized and does not require correction of the time decay of latent images of each color, and has been used frequently in recent years.

Problems to be Solved by the Invention However, in an image forming apparatus equipped with a rotary developing device, it is necessary to automatically replenish toner into each developing unit when the concentration of developer in each developing unit decreases. There is.

Conventionally, in a developing device using a magnetic brush method that uses a two-component developer consisting of toner and carrier, which is a magnetic powder, in addition to a developing chamber containing the developer, the developer in the developing chamber is kept at a predetermined concentration or lower. In such a case, a toner chamber is provided to replenish toner to the developing chamber, and toner for replenishment is stored in the toner chamber.

Therefore, in order to continuously copy a large number of sheets over a long period of time, the toner chamber should be made large so that a large amount of replenishment toner can be stored. became huge. A large developing device has a large moment of inertia, and it is extremely difficult and practically impossible to drive and control such a device at high speed.

Therefore, as a solution to this problem, a method has been proposed in which the toner chamber is made as small as possible, a cartridge-type toner replenisher is provided in the toner chamber, and the toner is replenished as needed via the toner replenisher.

However, when a large number of copies are required, it is necessary to frequently stop the developing device or drive it to the toner replenishing position, insert the toner replenisher into the developing unit, and replenish the toner chamber with toner. . Such work is not only extremely complicated work for the operator, but also causes a significant reduction in copying speed.

In addition, the developing unit must be structured so that the toner replenisher can be detachably attached, and a completely sealed structure cannot be achieved. Or the developer may scatter from the developing unit into the machine. Such toner or developer scattering not only contaminates the copying machine and operator, but can also cause the developer in each developer unit to mix with each other, making it difficult to obtain good quality copies.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to miniaturize each developing unit and also downsize the entire apparatus by providing a developer accommodating means for accommodating replenishing developer separately from each developing unit. An object of the present invention is to provide an image forming apparatus that can form images on a large number of sheets continuously for a long time.

Another object of the present invention is that the developing device transports each developing unit to a developing position by rotating each developing unit with a support means, and the developer from the developer storage means is transported along the rotational movement path of the developing unit. An object of the present invention is to provide an image forming apparatus which is configured to be replenished from the inside, suppresses scattering of the developer to the outside of the movement path, and prevents staining of the inside of the image forming apparatus by the developer.

Still another object of the present invention is that when the developing device is moved,
Provides an image forming device that can obtain high-quality images by preventing developer from scattering to the outside or mixing between developing units due to vibrations and shocks when starting and stopping. It is to be.

Means for Solving the Problems The above objects are achieved by an image forming apparatus according to the present invention. To summarize, the present invention includes an image carrier, a latent image forming means for forming an electrostatic latent image corresponding to each color image on the image carrier, and a developer of a different color applied to the image carrier. A plurality of developing units are provided, and by supporting and rotating the plurality of developing units, the required developing units are connected to a common one for each color.
a rotary support body that is moved to one development position; a plurality of hoppers that are provided outside the rotational movement path of the plurality of development units, each accommodating the developer of a different color; and from each of the plurality of hoppers; a plurality of developer transport paths for transporting replenishment developer to respective development units, the plurality of developer transport paths for replenishing developer to each development unit from inside the rotational movement path of the development unit; This is an image forming apparatus equipped with.

Embodiment Next, one embodiment of the image forming apparatus according to the present invention will be described in detail with reference to the drawings. As described above, in this embodiment, the image forming apparatus is a full-color electronic copying machine equipped with a dry rotary developing device, but the present invention is not limited to this embodiment.

Further, full-color electrophotographic copying machines perform various electrostatic latent image forming processes, such as primary charging-secondary charging/
Color separation exposure - so-called NP, including various processes of full-surface exposure
process or primary charging-color separation exposure steps. Although the so-called Carlson process and others may be used, in this embodiment, an electrophotographic copying machine to which the Carlson process is applied will be described.

FIG. 2 shows a schematic cross section of a full color electrophotographic copying machine. To explain the overall structure of the full-color electrophotographic copying machine, a photosensitive drum 1 having an electrophotographic photosensitive layer on its surface is arranged approximately in the center of the copying machine, and is rotated in the direction of arrow x (counterclockwise in FIG. 2). is rotated to

A primary charger 2 is installed approximately directly above the photosensitive drum 1.
A rotary developing device 100 equipped with a toner replenishing device 200 is located on the left side of the photosensitive drum 1 in FIG. Cleaning device 6
is placed.

Further, an optical system 10 is disposed in the upper part of the electrophotographic copying machine, and the image of the original O on the platen 7 is transferred to the exposure section 3 located between the primary charger 2 and the rotary developing device 100. and is configured to project the image onto the photosensitive drum 1. Although any optical system can be used as the optical system 10, in this embodiment, a first scanning mirror 11, and second and third scanning mirrors that move in the same direction at half the speed with respect to the first scanning mirror 11 are used. It is composed of mirrors 12 and 13, an imaging lens 14, and a fourth fixed mirror 15. The optical system 10 is a slit exposure type optical system well known to those skilled in the art, and further explanation of its operating principle is unnecessary. Further, the document illumination light source 16 is configured to move together with the first scanning mirror 11, and the color separation filter 17 is disposed between the fourth fixed mirror 15 and the exposure section 8.

Therefore, the first, second and third scanning mirrors 11,
The reflected light image of the original O scanned by 12 and 13 passes through the lens 14, passes through the fourth fixed mirror 15, is color separated by the color separation filter 17, and is imaged on the photosensitive drum 1 by the exposure section 8. be done.

Furthermore, it is imaged on full color 1.

Further, a fixing device 20 and a paper feed device 30 are arranged on the right side in FIG. 2 of the full-color electrophotographic copying machine, and the transfer drum 5 and the fixing device 2
Transfer paper conveyance systems 25 and 35 are provided between the transfer paper transfer system 0 and the paper feeding device 30, respectively.

In the above configuration, the photosensitive drum 1 is charged, exposed, developed, transferred, and cleaned for each color separated by the color separation filter 17 using the primary charger 2,
This is performed by an optical system 10, a rotary developing device 100, a transfer device 5, and a cleaning device 6.

The rotary developing device 100 includes developing units 101Y (yellow developing unit) and 101M, which are detachably held on a rotating body 300, which will be explained in more detail later.
(Magenta developing unit), 101C (Cyan developing unit) and 101B (Black developing unit)
The color-separated latent images of each color are visualized by the corresponding developing units.

The transfer device 5 typically includes a transfer drum 5b having a gripper 5a on its circumferential surface for gripping a transfer material, that is, a transfer paper P. The transfer device 5 connects the transfer paper cassette 31 or 32 of the paper feed device 30 to the transfer paper conveyance system 3.
Grip the leading edge of the transfer paper P fed through the gripper 5.
a, and rotate the photosensitive drum 1 to transfer the visible image of each color on the photosensitive drum 1. A transfer charger 5c is arranged inside the transfer drum 5 in the transfer area.

The transfer paper P onto which the toner image of each color has been sequentially transferred is released from the gripper 5a and peeled off from the transfer drum 5b by the separating claws 8. Next, the transfer paper P is transferred to the fixing device 20 by the transfer paper conveyance system 25.
sent to. The toner image on the transfer paper P is fixed onto the transfer paper by the fixing device 20, and then the transfer paper is discharged onto the tray 23.

Next, the rotary developing device 100 will be explained.

Referring to FIGS. 1 and 3 to 5, the rotary developing device 100 includes a plurality of developing units 101,
In this embodiment, the yellow developing unit 101Y,
Magenta developing unit 101M, cyan developing unit 101C, and black developing unit 101B.
four developing units, and the developing unit 101.
The rotary body 300 is provided with a rotating body 300 in which Y, 101M, 101C, and 101B are removably housed.

Each developing unit 101 basically has the same structure and shape, and its appearance is shown in FIG. 4, and its cross section is shown in FIG. 5. Further, FIG. 3 shows a rotating body 300 on which only the magenta developing unit 101M is mounted.

The developing unit 100 will be explained with reference to the magenta developing unit 101M. As the cross section is schematically illustrated in FIG. 5, the developing unit 101M
The front wall 102, the upper wall 103, the rear wall 104, the bottom wall 105, and both side walls 106, 107 (FIG. 4)
The developer housing is substantially integrally constructed with the developer housing.

A developing chamber 111 is defined below the developing housing, and developer D is stored therein. The developing chamber 111 is divided into first and second developing chambers 111a and 111b by a partition wall 108, and stirring screws 112 and 113 are provided in each developing chamber. A communication port (not shown) for each developing chamber is formed in a portion of the partition wall 108 adjacent to the side walls 106, 107, and therefore, by the operation of the stirring screws 112 and 113, the developer D is transferred to the first developing chamber→ It is circulated from the second developing chamber to the first developing chamber.

A developing roller 11 is located above the second developing chamber 111b.
0, a portion of which protrudes from a window 114 formed in the front wall 102. Developing roller 110
has a magnet roller located inside and a sleeve roller made of non-magnetic material such as brass or stainless steel surrounding the magnet roller, and are rotated in opposite directions (not shown).

The area involved in development of the developing roller 110 is regulated by the window 114 of the front wall 102, and the developing roller 110
The window 114 on the front wall and the developing roller 110 are as described in Japanese Patent Publication No. 55-20579 filed by the present applicant.
Even if the gap faces downward, the magnetic field works in conjunction with the developer to prevent the developer from falling through the gap.

As is clear from the above description, the developer used in this embodiment includes a toner based on a polyester resin containing dyes or pigments of each color,
It is a two-component developer consisting of a carrier made of magnetic powder.

Above the first developing chamber 111a is a pre-developing chamber 11.
1c is defined and separated from the developing roller 110 by an upper partition wall 108a connected to the partition wall 108. Further, a rear wall 10 defining a preliminary development chamber 111c
4 is formed with a toner receiving port 120M that receives toner for replenishment from the toner replenishing device 200, and the receiving port 120M is closed due to its own weight.
Toner backflow prevention shutter 125M that opens and closes
is applicable.

Developing unit 101 configured as described above
is stored in a developing unit storage chamber 301 of the rotating body 300, as shown in FIG. Third
In the figure, the magenta developing unit 101M is the rotating body 3.
00 is shown stored in a storage room 301.

The rotating body 300, as illustrated in FIG.
A developing unit storage chamber 301 that stores each developing unit 101 is a substantially entire structure formed at equal intervals in the circumferential direction, and a circular hole 302 is formed at the center of rotation along the rotation axis. be done.
Bearings 303 and 304 are provided at both inner ends of the circular hole 302, and the rotating body 300 is rotatably attached to the hollow shaft 310 via the bearings 303 and 304. Further, the hollow shaft 310 is fixed to both side plates 50 and 51 of the main body of the copying machine via fixtures 52 and 53. Further, a rotary body driving gear 320 is fixed to the rear end of the rotary body 300, and as shown in FIG. be done. Further, positioning of the rotating body 300 is performed by a positioning means 420. The means 420 includes a positioning pin 421 that engages with a notch 331 of a positioning ring 330 integrally attached to the rotating body drive gear 320, and a solenoid 425 that operates the pin about a shaft 421a.

Next, the toner replenishing device 200 will be explained.

As can be seen from Figures 1, 2 and 7,
The toner replenishing device 200 includes a large toner storage container (hereinafter simply referred to as a "hopper") 201 that stores toner for replenishment. In this embodiment, the hopper 201 is comprised of a yellow hopper 201Y, a magenta hopper 201M, a cyan hopper 201C, and a black hopper 201B, corresponding to each developing unit, and is arranged approximately above the rotary developing device 100.

Hoppa 201Y, 201M, 201C and 20
1B has a yellow pipe 202Y, a magenta pipe 202M, and a magenta pipe 202M, respectively, as shown in FIG.
Cyan pipe 202C and black pipe 202
One end of B is connected. The other end of each pipe is led into the hollow shaft 310 (FIG. 1).

As best illustrated in FIG.
An intermediate pipe 350 is disposed between the outer periphery of the rotating body 10 and the inner wall of the circular hole 302 of the rotating body 300.
2 and 353 to be rotatably attached to the hollow shaft 310. Therefore, an annular chamber 351 is formed between the hollow shaft 310 and the intermediate pipe 350, and the thickness S of the annular chamber 351 is approximately 8 mm in this embodiment, although it is not limited to this. Further, in the annular chamber 351, a partition seal member 354,
355 and 356 are arranged at approximately equal intervals, and the annular chamber 351 has annular compartments 351Y, 351M, and 351
It is divided into C and 351B. Partition seal member 3
54 to 356 may be sliding bearings.

The hollow shaft 310 has the respective annular compartments 351Y, 351M, 3 extending through its substantially lower wall portion.
Toner supply port 36 communicating with 51C and 351B
1Y, 361M, 361C and 361B are formed. The toner supply ports 361Y, 361M, 36
1C and 361B are connected to the other ends of a yellow pipe 202Y, a magenta pipe 202M, a cyan pipe 202C, and a black pipe 202B, each of which has one end connected to the hopper 201 described above.

On the other hand, annular compartments 351Y, 351M, 351C
Relay ports 362Y, 362M, 362C, and 362B are aligned with the receiving port 120 of each developing unit and the opening 305 of the rotating body 300, respectively, in the intermediate pipe 350 portion defining the intermediate pipes 351B and 351B.
is formed. Therefore, the relay ports 362Y, 362
M, 362C and 362B are formed so as to be out of phase with each other by 90° in the circumferential direction, as shown in FIGS. 1 and 8. Further, the intermediate pipe 350 is fixed to the rotating body 300 by appropriate means (not shown), and when the rotating body 300 rotates, the intermediate pipe 350 also rotates together with the rotating body 300, and the rotating body 300 rotates 90 degrees. Each time the relay port is connected to the rotating body 3
It is placed directly below 00. An annular sealing member 306 such as a urethane foam is installed around the outside of the relay port between it and the opening 305 of the rotating body 300.
is placed.

In the above description, the intermediate pipe 350 is integral, but as shown in FIG. 9, for example, the intermediate pipe 350 is divided into a plurality of pieces, and in this embodiment, the intermediate pipes 350a and 350b are divided into four pieces. ,3
50c and 350d, each partition seal member 35
4, 355 and 356 can also be configured to have bearing performance. When the intermediate pipe 350 is divided in this manner, there is an advantage that coaxiality between the partition seal members can be relatively relaxed.

In the above configuration, a toner conveying screw 203 is inserted into each pipe 202 that communicates each hopper 201 and each annular compartment 351, and one end of the screw 203 is connected to each toner supply hole 361.
The other end extends through the inside of the hopper 201, and is rotationally driven by the drive motor M2.

Due to the action of the toner conveying screw 203, the toner in the hopper 201 is fed through the pipe 202 to the toner replenishment hole 361, and falls from the replenishment hole 361 in an approximately vertical direction due to gravity, and is deposited in the annular compartment 35.
1. Since the annular compartments 351 are isolated from each other by the bearing and the partition seal member, the toner supplied to each annular compartment 351 does not mix with each other or scatter to the outside. Further, each annular compartment 351 has a fixed hollow shaft 31
Since the hollow shaft 310 and the intermediate pipe 350 are separated by a distance S, the hollow shaft 310 and the intermediate pipe 350 are brought into a locked state with each other by the toner, and the intermediate pipe 350 is held. This does not increase the driving load on the rotating body.

Toner supply device 200 configured as described above
The operation of the rotary developing device 100 will now be explained.

In FIG. 5, the yellow developing unit 101
Y is at the toner replenishment position. The rotating body 300 is rotated clockwise in FIG. 5, and the developing unit 101Y, which has completed the developing operation, is rotated by 90 degrees until it reaches the toner replenishment position, and is brought into a horizontal position. Even in such a state, as described above, the toner in the development guide does not leak to the outside or scatter from the development roller 110 portion.

On the other hand, the toner backflow prevention shutter 125Y, which opens and closes the toner receiving port 120Y by its own weight, rotates around the pivot 126 as the rotating body 300 rotates, moves away from the toner receiving port 120Y, and becomes vertical at the toner replenishing position. Entrance 120
Completely open Y. At this time, if the motor M2 of the yellow hopper 201Y is energized, the toner conveying screw 203Y is driven, and the toner in the yellow hopper 201Y passes through the pipe 202Y.
It is supplied to the preliminary development chamber 111Y of the development unit 101Y from the relay port 360Y via the annular compartment 351Y.

When the toner supply is finished, the yellow developing unit 101Y is further rotated by 90° due to the rotation of the rotating body 300.
The black developing unit 101 is rotated in FIG.
It is brought to an inverted state as shown in B. Developing chamber 11
1. In particular, the developer in the first developing chamber 111a is replenished and moves together with the toner to the pre-developing chamber 111Y,
Some degree of mixing of developer and toner is achieved during this process. Also, at this time, the shutter 125Y will rotate due to its own weight and close the toner receiving port 120Y. Further, even if the rotating body 300 rotates further and the yellow developing unit 101Y is brought to the position of the black developing unit 101B, and the toner backflow prevention shutter 125Y is turned sideways, which is opposite to the replenishment state, the toner backflow prevention shutter 125Y is completely filled with toner. Since the receiving port 120Y is closed, toner does not leak from the developing unit.

The developing unit 101Y is further rotated by 90 degrees to reach the developing position, that is, the state of the developing unit 101C in FIG. In the process of this rotational movement, the developer in the preliminary development chamber 111Y is caused to flow by gravity toward the first development chamber 111a.
In order to statically stir the flow, it is effective to provide a protrusion 109 in the shape shown in the figure on the rear wall 104 of the developing unit, which has the effect of stirring the developer. or,
By such movement and stirring of the developer and replenishment toner within the preliminary development chamber 111C, the two are mixed fairly uniformly.

Furthermore, the developer in the first developing chamber 111a is made to have a uniform concentration by the action of the stirring screws 112 and 113. In addition, the toner replenishment hole is arranged as far upstream as possible in the transporting and stirring direction of the stirring screw 112 to increase the amount of toner that can be replenished and to lengthen the transport and stirring path by the stirring screw 112, thereby achieving a developer with a uniform toner concentration. It is possible to create D.

The above description has been made only regarding the toner replenishment operation of the yellow developing unit 101Y, but the same applies to the other developing units.

FIG. 10 is a flowchart showing one embodiment of the operation of the image forming apparatus, particularly the toner replenishing device 200, according to the present invention. First, the toner concentration of the developer coated on the developing roller of the developing unit is detected (step 1). Toner concentration detection is performed at the developing position (magenta developing unit 101 in Figure 5).
This is performed on the developing unit that has arrived at position M). Although various methods of toner concentration detection can be used, one example is shown in FIG. In Figure 11,
The toner concentration detector P has a light source P ₁ and a light receiving element P ₂ , and is fixed to the hollow shaft 310 . On the other hand, the detection section 50 consists of light guides 51 and 52 and is attached to the rotating body 300 or the developing unit.
One end of the light guides 51 and 52 is connected to the developing roller 11.
0 surface, and the other end is adjacent to the light source _P1 and the light receiving element _P2 . Therefore, when the developing unit is placed at the developing position, the light from the light source _P1 is projected from the light guide 52 onto the surface of the developing roller.
The reflected light passes through the light guide 51 to the light receiving element P ₂
The light is received by the The amount of toner in the developer is measured based on the amount of light reflected from the developing roller. In this detection device, since the detector P that requires power supply is fixed, power supply is easy, and the connection between the detector P and the detection section 50 is positioned close to the center of rotation of the developing unit. Detector P
It is easy to determine the connection position between the detection unit 50 and the detection unit 50.

If it is determined in step 1 that the toner density in the developing unit is sufficient, control for creating a normal color copy will continue; if it is determined that the toner density is low, the current copying process will be continued. 1
It is decided to continue copying only the sheets (steps 2 and 3).

Next, it is determined whether one color copy with low toner density has been completed (step 4),
When the process is completed, the process of creating the next color copy is not started, but the developing unit determined to have a low toner density is moved to the toner replenishment position (FIG. 4) (step 5). It is determined that the target developing unit has arrived at the predetermined position (step 6),
A replenishment operation is performed for the replenishment system containing toner of the same color (step 7), and when it is determined that the replenishment operation has been completed, the routine returns to the normal sequence (step 8). If continuous copying is in progress, copying of the remaining number of sheets is continued.

Incidentally, the detection of toner density is not only carried out for the developing unit during the developing operation, but also may be carried out for the developing unit passing through the above-mentioned detection position. However, since toner is consumed during development, developing units that are not used for development do not need to be detected. Further, since the developing unit that is not used for development does not need to stop at the developing position, that is, the measuring position, the measuring position passes through at high speed. Therefore, detecting a developing unit that moves at high speed requires lowering the detection accuracy or providing sophisticated judgment means, and therefore it is not possible to measure only the developing unit that is used for development and is stopped. It is valid.

Furthermore, in addition to the toner concentration detection described above, a well-known developing unit type and position detector for confirming the type (color) and position of the current unit currently detecting the toner concentration is installed on the hollow shaft 310 in the same way as the toner concentration detector P. The detector S may be fixed to the detector S, and the color signal of the developer and the position signal of the developing unit may be transmitted to the detector S using a light guide.

The toner concentration detector P and the type and position detector S can also be fixed to the main body of the copying machine instead of the hollow shaft 310.

FIG. 12 is a block diagram showing the control mode of the image forming apparatus according to the present invention, particularly the toner replenishing device and related devices. The entire copying machine is controlled by a sequence controller (CPU) 60.

If the yellow developing unit 101Y is currently developing, the CPU 60 determines that the developing unit 101Y is located at the developing position based on the type and position detector S signals. Here, when the toner concentration detector P detects "insufficient toner concentration", this signal is transmitted to the input interface 61 and I/O port 62, and then to the CPU 60.
The CPU 60 works on the program memory 63,
To continue development until the final color for only one sheet currently being copied. After this copying process is completed, the drive circuit MD drives the motor M1 to rotate the rotating body 300. Developing unit 101Y
When it reaches the replenishment position, the rotating body 30 is activated by the signal from the detector S.
0 is stopped, and the replenishment drive motor M2 is driven to replenish yellow toner. The above series of operations is similarly applied to the magenta developing unit, cyan developing unit and black developing unit.

The above description has been made regarding an embodiment in which the image forming apparatus according to the present invention is equipped with a developing device that uses a two-component developer as the developer, but the present invention provides an image forming apparatus that is equipped with a developing device that uses a one-component developer as the developer. It is similarly applicable to forming devices. In this case, replenishment of the developer to the developing device will be determined not by changes in the concentration of the developer but by the remaining amount or presence or absence of the developer.

Effects of the Invention The toner replenishing device according to the present invention configured as described above is provided with a developer accommodating means for accommodating replenishing developer separately from each developing unit, thereby reducing the size of each developing unit and reducing the size of the entire device. It is also possible to downsize the image forming apparatus, thereby making it possible to continuously form a large number of images for a long period of time.

The developing device is configured to convey each developing unit to a developing position by rotationally moving each developing unit using an indicating means, and to replenish the developer from the developer storage means from inside the rotationally moving path of the developing unit. By doing so, it is possible to suppress the developer from being scattered outside the movement path, and to prevent staining of the image forming apparatus by the developer.

High-quality images can be obtained without developer being scattered outside or mixed between developing units due to vibrations and shocks when the developing device is moved, started, and stopped. .

It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a toner replenishing device provided in an image forming apparatus according to the present invention. FIG. 2 is a schematic cross-sectional view of a full-color electrophotographic copying machine that is an embodiment of the present invention. Third
The figure is a perspective view of a rotary developing device equipped with a toner replenishing device. 4 is a perspective view of the developing unit of the rotary developing device of FIG. 3. FIG. FIG. 5 is a schematic sectional view of the rotary developing device of FIG. 3. Figure 6 shows
FIG. 4 is a perspective view of the rotary developing device shown in FIG. 3, seen from the rear side. 7 is a perspective view showing a toner replenishing system of the toner replenishing device of FIG. 1. FIG. FIG. 8 is a partially cutaway perspective view of the toner supply system. FIG. 9 is a schematic sectional view showing another embodiment of the toner replenishing device. FIG. 10 is a control flow diagram illustrating one embodiment of the operation of the toner replenishing device. FIG. 11 is a perspective view showing one embodiment of the toner concentration detection means. FIG. 12 is a schematic control block diagram illustrating the operation of the rotary developing device and the toner replenishing device. 100: Rotary developing device, 101Y, 101M,
101C, 101B: developing unit, 120: toner receiving port, 125: shutter plate, 200: toner supply device, 201: hopper, 202: pipe,
203: Screw, 300: Rotating body, 310:
Hollow shaft, 350: intermediate pipe, 351: annular chamber,
351Y, 351M, 351C, 351B: Annular compartment, 352, 353: Bearing, 354, 355,
356: Partition seal member, 361: Toner supply port, 362: Toner relay port.

Claims (1)

[Scope of Claims] 1. An image carrier, a latent image forming means for forming an electrostatic latent image corresponding to an image of each color on the image carrier, and applying developers of different colors to the image carrier. a plurality of developing units; a rotary support that supports and rotates the plurality of developing units to move the required developing units to a common development position for each color; a plurality of hoppers each accommodating developer of a different color, and a plurality of developer transfer paths for transporting replenishment developer from each of the plurality of hoppers to a corresponding development unit; hand,
An image forming apparatus comprising: a plurality of developer transport paths for supplying developer to each developing unit from inside the rotational movement path of the developing unit. 2 A cylindrical body that forms an annular chamber between a hollow fixed shaft that rotatably supports the first rotating support and the hollow shaft that surrounds this hollow shaft, and that is different in the axial direction and the circumferential direction. A cylindrical body having a plurality of developer discharge openings corresponding to the respective developing units at positions and rotating integrally with the rotary support body, and the plurality of developer transfer paths are respectively formed in the hollow of the hollow shaft. The developing unit is in communication with the annular chamber through the inside of the tubular body, and the developer discharge opening corresponding to the developing unit provided in the cylindrical body is provided to the developing unit that has reached one common replenishment position for each developing unit. 2. The image forming apparatus according to claim 1, wherein said transfer path communicates with said transfer path. 3. The image forming apparatus according to claim 2, further comprising a plurality of partitions that partition the annular chamber for each color of the developer.