JP2001154485A - Exchange method of developer in developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain developed image with a high definition in display from immediately after exchange of developer by preventing developing due to clumping of toner generated by a developing procedure immediately after two component developer that has finished its service life is exchanged to a new two component developer in a developing device. SOLUTION: Relating to the device, a wall surface of a developing container 11 is cleaned by feeding raw carrier to the developing container 11 and driving the developing device 12 for 5 minutes after the used two component developer 10 that has finished its service life is ejected from a developer ejecting opening 33. After this, the raw carrier is ejected from the developer ejecting opening 33 and the exchange of the developer is carried out by feeding the new two component developer to the developing container 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for replacing a developer in a developing device mounted on an image forming apparatus such as a printer or an electrophotographic apparatus.

[0002]

2. Description of the Related Art In recent years, a magnetic brush developing apparatus mounted on a printer or an electrophotographic apparatus, which forms a magnetic brush using a two-component developer composed of a toner and a carrier and develops an electrostatic latent image, has recently been used in image forming apparatuses. Due to the colorization, a plurality of developing devices are provided in the main body, for example, like a tandem type color image forming device in which four color developing devices are mounted in parallel in the horizontal direction. As the size of the color image forming apparatus is reduced, the size of the developing device is also required to be reduced. To achieve this, the storage amount of the two-component developer in the developing container tends to be reduced. In addition, in the color image forming apparatus, the area ratio of the image portion is higher than that of the conventional monochrome image, and the toner consumption is smaller than that of the monochrome image regardless of the reduction in the amount of developer stored due to the downsizing of the developing device. Is made up of many.

As a result, in a color image forming apparatus, the amount of replenishment toner for supplementing toner consumed during development increases, and the developer deteriorates more severely than in a conventional monochrome image, thereby shortening the life of the developer. In addition, the number of times of maintenance of the developer replacement becomes larger than that of the monochrome developing device, and since the developer replacement is required for each of the four color developing devices, the maintenance frequency is quadrupled.

For this reason, in a color image forming apparatus, a developer discharge port for discharging the developer is conventionally provided at the end of the developing container so as to simplify the maintenance for replacing the developer. By driving the developing device with the outlet open, all the used developer that has reached the end of its life is automatically discharged from the developing container, and then a new developer is automatically supplied from the toner supply port provided in the developing container. Replenishment and replacement of the developer were performed automatically.

[0005]

However, when the developer is automatically replaced by the above-described method, during the initial development immediately after the replacement of the developer, the toner solidified in a granular form adheres to the image. And the display quality is significantly reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and provides a developing apparatus which can obtain a good and high-quality developed image without causing toner clamping even in the initial development immediately after the replacement of the developer. An object of the present invention is to provide a method for replacing a developer.

[0007]

According to the present invention, as a means for solving the above problems, there are provided a developing container for containing a two-component developer comprising a toner and a carrier, Developing means for magnetically transporting the component developer and applying the toner to the electrostatic latent image carrier, wherein the two-component developer contained in the developing container is provided in the developing device. A second step of supplying only the carrier into the developing container after discharging the two-component developer, and a step of stirring and transporting the carrier in the developing container to perform the development. A third step of cleaning the inside of the container, a fourth step of discharging all the carrier after the cleaning is completed, and a fifth step of supplying a new two-component developer into the developing container. Also It is.

According to the present invention, by automatically discharging used developer, the present invention cleans the inside of the developing container using only the carrier, and then supplies a new developing agent, so that the developer is replaced immediately after the replacement. A good developed image can be obtained without toner clamping even in the initial development.
The purpose is to improve image quality.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described. In the conventional developer replacement method, when a developing operation is performed immediately after replacement with a new developer, a toner clamp is generated on a developed image until the number of sheets reaches about 500 from the beginning, and display quality is deteriorated. . This is because the toner stuck to the wall of the developing container remains without being peeled when the used developer is discharged, and when new developer is replenished in this state, most of the toner is peeled off from the wall at the time of replenishment and the developing agent is removed. Since the toner is mixed into the toner as a solidified particle, the solidified toner adheres to the image during the initial development immediately after the replacement of the developer.

Accordingly, the present invention is to prevent the toner clamp from occurring by discharging the developer which has reached the end of its life from the developing container, cleaning the wall surface of the developing container, and then supplying the developing container with a new developer. It is.

Based on the above principle, the present invention is shown in FIGS.
This will be described with reference to the embodiment shown in FIG. FIG. 1 shows four sets of image formation in which a developing device 12 that circulates a two-component developer 10 in a vertical direction within a developing container 11 develops a photosensitive drum 13 that is an electrostatic latent image carrier. Means 14a-
FIG. 14 is a schematic configuration diagram showing a four-tandem tandem color printer 17 that arranges 14d in parallel along a transfer and conveyance belt 16 and obtains a color image.

Each of the image forming means 14a to 14d includes a charging charger 18 around the photosensitive drum 13 along the rotation direction thereof, and an exposure device 20 for converting an image signal into an optical signal and scanning and exposing the photosensitive drum 13. An exposing unit 21, a developing device 12, a transfer / peeling charger 22, a cleaning device 23, and a static elimination lamp 24 are sequentially arranged. The developing device 12 of each of the image forming units 14a to 14d develops with the two-component developer 10 including yellow (Y), magenta (M), cyan (C), black (BK) toner and carrier, respectively. It is made to do.

Reference numeral 40 denotes a registration roller which conveys a sheet supplied from a paper cassette (not shown) or the like in synchronization with the toner image on the photosensitive drum 13. Reference numeral 41 is formed on the sheet after the transfer is completed. A fixing roller for fixing a full-color toner image.

Next, the developing device 14 will be described in detail. A developing roller 27 is provided at a position facing the photosensitive drum 13,
350 g of a two-component developer 10 containing a toner composed of a resin having an average particle diameter of about 5 to 10 μm and a carrier composed of a magnetic material such as iron or ferrite having a particle diameter of 30 to 100 μm can be stored. An upper screw 30a is provided in the upper transport path 28a of the developer container 11 partitioned by the lower transport path 28b, and a lower screw 30b is provided in the lower transport path 28b. By providing the upper and lower transport paths 28a and 28b in the developing container 11 in this manner, the width of the developing device 12 can be reduced, and the width of each of the image forming units 14a to 14d of the color printer 17 can be reduced. The size of the device can be reduced.

The developing roller 27 has an N-polar developing magnetic pole N1.
And a recovery magnetic pole N3, and a magnetic roller 27a having transport magnetic poles S1, S2, and N2 arranged so that the N polarity and the S polarity are alternately arranged between them, and a development that rotates around the magnet roller 27a in the direction of arrow r. Sleeve 27
b. Reference numeral 31 denotes a doctor blade for regulating the thickness of the magnetic brush formed around the developing roller 27.

Reference numeral 32 denotes a developer supply port provided on the upper surface of the end portion of the developing container 11 to supply replenished toner or new developer. Further, a developer discharge port 33 which is opened and closed by a shutter (not shown) on the end bottom surface opposite to the replenishing port 32 of the developing container 11 to discharge the used developer which has reached the end of its life.
Are formed.

Next, the operation will be described. When a color image signal is sent to the color printer 17 by a print start input, the exposure device 20 and the image forming units 14a to 14a-1
4d is driven, and the photosensitive drum 13 is charged, exposed, and developed according to the rotation in the direction of the arrow x to form toner images of yellow, magenta, cyan, and black, respectively. Next, the photosensitive drum 13 is supplied to the transport belt 16 by a registration roller 40 so as to be synchronized with the toner image on the photosensitive drum 13, and is sequentially placed on a sheet paper (not shown) to be yellow, magenta, cyan, and black. Are sequentially transferred in a multiplex manner.

After the transfer, the sheet having the color toner image is peeled off from the conveyor belt 16, is heated and fixed by the fixing roller 41, and is then discharged onto a discharge tray (not shown). On the other hand, after the transfer of the toner image is completed, the photosensitive drum 13 is brought into a state where the next image can be formed via the cleaning device 23 and the discharging lamp 24, and the above-described printing operation is repeated until the required number of sheets is reached.

Next, the operation of the developing device 12 will be described in detail. When the printing is started, the upper and lower screws 30a and 30b rotate in the developing device 12, and the two-component developer 10 is agitated and conveyed in the direction of arrow t in the upper conveying path 28a while being transferred to the developing roller 27 as indicated by arrow v. The toner is supplied and further conveyed to the lower conveyance path 28b together with the replenishment toner supplied from the replenishment port 32. In the lower transport path 28b, the upper transport path 28
a, and the two-component developer recovered from the recovery magnetic pole N3 of the developing roller 27 is agitated and transported in the direction of arrow u by the screw 30b.
The two-component developer 10 is circulated and conveyed in the vertical direction in the developing container 11 so as to be conveyed in the direction 8a.

On the other hand, in the developing roller 27, a magnetic brush (not shown) is formed with the rotation of the developing sleeve 27a in the direction of the arrow r, and the layer thickness is regulated by the doctor blade 31, so that the photosensitive member is Development is performed using a developing electrode N1 provided at a position facing the drum 13. Thereafter, the two-component developer 10 remaining on the peripheral surface of the developing sleeve 27a is recovered to the lower transport path 28b as indicated by the arrow w.

Next, a method of replacing the two-component developer 10 will be described with reference to a flowchart shown in FIG. When the number of development operations reaches a predetermined number of lives while the development device 12 performs the development operation, a code for automatically discharging the developer is input to the main body of the color printer 17 from a control panel (not shown) in step 100. I do. As a result, in step 101, the toner cartridge attached to the developer supply port 32 is removed, the shutter (not shown) of the developer discharge port 33 is opened, and the developing device 12 is driven in this state, and the vertical screw 30a , 30b, all the used two-component developer 10 in the developer container 11 is discharged from the developer discharge port 33.

Next, at step 102, the developer outlet 33
The shutter (not shown) is closed, the developing device 12 is driven, and only the carrier not mixed with toner (raw carrier) is supplied from the developer supply port 32 while rotating the upper and lower screws 30a and 30b. 8 of 10 stitches
Feed until 0% is reached. Then, when the supply amount of the raw carrier reaches 80% of the insertion amount of the two-component developer 10, the developing device 12 is driven for 5 minutes in that state, and the toner fixed on the wall of the developing container 11 is scraped off by the raw carrier. The inside of the developing container 11 is cleaned.

After a lapse of 5 minutes, at step 103, the shutter (not shown) of the developer outlet 33 is opened, and the developing device 12
To drive the raw carrier in the developing container 11
Developer outlet 3 with fixed toner scraped off the wall
Discharge from 3. Next, in step 104, the shutter of the developer discharge port 33 is closed, a developer cartridge (not shown) for storing a new two-component developer is attached to the developer supply port 32, and the developing device 12 is driven to In step 106, the toner concentration controller (ATC) is adjusted, a toner cartridge (not shown) is attached to the developer supply port 32, and the developer replacement operation is completed. However, in consideration of the fact that about 70 g of raw carrier remains in the developing container 11 after the discharging of the raw carrier in step 103, the developing container 11
The toner concentration ratio of a new two-component developer 10 supplied to
Set higher than when used.

When the development is performed after replacing the two-component developer 10 by this method, a good developed image can be obtained with a uniform toner without causing toner clamping even in the initial development immediately after the replacement of the developer. Was. FIG. 8 is a graph comparing the occurrence of toner clamp immediately after the replacement of the developer with the conventional one. In the conventional replacement method, the toner clamp occurred immediately after the replacement of the developer until the number of passed sheets reached 500. On the other hand, in the present embodiment, no toner clamp was observed.

In this embodiment, the state of occurrence of toner clamp was examined by changing the cleaning time with the raw carrier. As shown in FIG. 9, if the cleaning time was 5 minutes or more, the initial state immediately after the replacement of the developer was obtained. It was found that no toner clamp was generated. Further, in this embodiment, the state of toner clamp generation was examined by changing the supply amount of the raw carrier to the developing container 11, and the result was as shown in FIG. 80 of scale
%, It was found that toner clamping did not occur from the initial stage immediately after the replacement of the developer.

With this configuration, when replacing the two-component developer, the used developer is discharged, and the inside of the developing container 11 is cleaned with a raw carrier to remove the toner adhered to the side wall of the developing container 11. Further, after the raw carrier is discharged after the cleaning is completed, a new two-component developer 10 is supplied, so that a good developed image with a uniform toner can be obtained without causing a toner clamp even in the initial development immediately after the replacement of the developer. Can be Thereby, regardless of the downsizing of the developing device 12 due to the downsizing of the color printer 17, an image with high display quality can be formed without impairing the maintainability.

The present invention is not limited to the above-described embodiment, and can be variously changed in design. For example, the structure of the developing container is not limited, and the arrangement of the screws is also arbitrary. However, if the screws are arranged vertically, the width of the developing device can be reduced, and the size of the color image forming apparatus can be reduced. If the toner clamp does not occur after the replacement of the developer, the supply amount of the raw carrier at the time of cleaning or the cleaning time by the raw carrier is also arbitrary. Further, the toner concentration ratio of the new developer supplied after the completion of the cleaning is also arbitrary according to the amount of the raw carrier remaining in the developing container.

[0028]

As described above, according to the present invention, when the developer of the developing device is replaced, the toner fixed on the side wall of the developing container is cleaned with a raw carrier, and then a new developer is supplied. Even in the initial development immediately after the replacement of the developer, a good developed image with a uniform toner can be obtained without causing toner clamping.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram illustrating a developing device according to an embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a developing device according to the embodiment of the present invention.

FIG. 4 is a front view of a part of the developing device according to the embodiment of the present invention as viewed from a developing roller side.

FIG. 5 is a plan view of a part of the developing device according to the embodiment of the present invention as viewed from a bottom surface.

FIG. 6 is a schematic explanatory view showing a conveying direction of a two-component developer in a developing container of the developing device according to the embodiment of the present invention.

FIG. 7 is a flowchart illustrating a method for replacing a two-component developer according to the embodiment of the present invention.

FIG. 8 is a graph showing a state of occurrence of a toner clamp immediately after a developer replacement according to the embodiment of the present invention, in comparison with a conventional replacement method.

FIG. 9 is a graph showing a state of occurrence of a toner clamp caused by changing a cleaning time by a raw carrier according to the embodiment of the present invention.

FIG. 10 is a graph showing how toner clamps are generated by changing the supply amount of raw carriers according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 two-component developer 11 developing container 12 developing device 13 photoreceptor drums 14a to 14d image forming means 17 color printer 27 developing roller 28a upper transport path 28b lower transport path 30a upper screw 30b Lower screw 32: developer supply port 33: developer discharge port

Claims (4)

[Claims] A developing container for storing a two-component developer including a toner and a carrier; and a magnetic container for conveying the two-component developer agitated and conveyed in the developing container to the electrostatic latent image carrier. A method of exchanging a developer in a developing device having a developing means for applying toner, a first step of discharging all of the two-component developer contained in the developing container, and after discharging the two-component developer. A second step of supplying only the carrier into the developing container, a third step of stirring and transporting the carrier in the developing container to clean the inside of the developing container, and the carrier after the cleaning is completed. And a fifth step of supplying a new two-component developer into the developing container. A method of exchanging the developer in the developing device, comprising: 2. The method according to claim 1, wherein a cleaning time of the carrier in the developing container in the third step is 5 minutes or more. 3. The method according to claim 2, wherein the amount of the carrier supplied into the developing container in the second step is 80 to 100% of the two-component developer stored in the developing container. 3. A method for replacing a developer in the developing device according to claim 1. 4. The method according to claim 1, wherein the specific toner concentration of the new two-component developer supplied in the fifth step is set higher than the specific toner concentration of the two-component developer during a normal developing operation. A method for replacing a developer in the developing device according to claim 1.