JPH0437773A - Color image forming device - Google Patents

Abstract

PURPOSE:To increase the toner capacity of a developing device for black developer with high frequency in use so as to eliminate the fear of the intermission of replenishment and to prevent scraped fatigue developer from flowing in an adhesion chamber soon by constituting a developer replenishing chamber for the black developer so that it may be larger than any other replenishing chamber, providing a partition plate which divides the replenishing chamber to a fresh developer replenishing path and a used developer collecting path and providing a stirring screw in each path so that the direction of the flow of the replenished developer may be reverse to that of the flow of the collected developer. CONSTITUTION:In the developing device 11 for black toner, the lower side of a developing roller 11a is divided to the developer replenishing chamber H and the developer adhesion chamber F by a scraping plate R contacting with the roller 11a, which is the same as other developing devices 8-10, but the chamber H is constituted larger than any other replenishing chamber. Then, the partition plate 11f which divides the replenishing chamber H to the fresh developer replenishing path h1 and the used developer collecting path h2 is provided in the chamber H. The stirring screws S3 and S4 are respectively provided in the path h1 which is replenished with the toner from a toner replenishing port 11d and the path h2 so that the directions of both flows of the developer may be reverse, and the flow of the fresh developer and the flow of the used developer are not mixed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a color image forming apparatus that forms a toner image on a photoreceptor belt using an electrophotographic method and then transfers it to a recording paper to obtain a color image. It is related to.

[Conventional technology]

Generally, the image forming principle of this type of color image forming apparatus is as follows: ■Photoreceptor drum method ■Photoreceptor belt method It is broadly divided into two types.

Among these, the photoreceptor drum method forms a multicolor image on a photoreceptor drum with a photoconductor formed on its surface by repeating latent image formation and development according to the number of separated colors of the original image. A color copy is obtained by transferring a multicolor image onto recording paper (for example, Japanese Patent Laid-Open No. 75850/1983). This method has the advantage of stabilizing the formation of a latent image and making it easy to transfer it to the recording paper. However, as the original image becomes larger, the diameter of the photoreceptor drum also increases, and the recording paper from the drum becomes larger. This method has disadvantages in that the separability of the components deteriorates, and the overall size and complexity of the device cannot be avoided. In addition, repeated development according to the number of separated colors tends to cause misalignment during transfer to recording paper.
Another drawback is that precise multicolor copying is difficult.

Therefore, the basic process of a method in which a color toner image is superimposed on the drum by rotating the photoreceptor drum multiple times to form an electrostatic latent image, and then transferred to recording paper one at a time is as follows.
Disclosed by the present applicant (Japanese Unexamined Patent Publication No. 60-7585)
No. 0, No. 60-76766, No. 60-95456,
No. 60-95458, No. 60-158475). In a color image forming apparatus that uses such superimposed images, a plurality of developing units containing color toner of each color are arranged in parallel around the periphery of the photosensitive drum.

On the other hand, in the photoconductor belt method, a photoconductor is applied onto a flexible belt stretched between rotating rollers, and an electrostatic latent image is formed on the belt. Compared to this, it has the advantage that space can be used more effectively and a compact color image forming apparatus can be constructed. Also, in this method,
Since the recording paper can be separated using a small-diameter rotary roller travel section (large curvature), there is also the advantage of excellent separation performance.

[Problems to be Solved by the Invention] The conventional color image forming apparatus described above has a problem in that the image component corresponding to the black developer is likely to deteriorate.

That is, conventional belt-type color image forming apparatuses basically print C (cyan), M (magenta), and Y (yellow).
, Bk (black) are arranged in parallel below the photoreceptor belt, but among these four colors, black toner is used less frequently. It is much larger than the other three colors, and is therefore used in large quantities. This may cause problems such as (1) out of supply of black toner (2) insufficient stirring of black toner.

In view of the above points, it is an object of the present invention to provide a color image forming apparatus that can prevent the occurrence of such troubles regarding black developer and can be maintained in the same manner as other color toners.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a developer that is divided into a developer supply chamber and a deposition chamber by a magnetic developing roller and a developer scraping plate, and in which the developer can be circulated by a stirring screw in each chamber. In a color image forming apparatus in which a group of developing devices each having a storage box are arranged in parallel below a photoreceptor belt, a developer replenishing chamber of a predetermined developing device among the developing devices is configured to be wider than other replenishing chambers. In addition, a partition plate is provided to divide the replenishment chamber into a fresh developer supply path and a used developer recovery path, and a stirring screw is installed in each flow path so that the replenishment developer flow and the recovered developer flow are in opposite directions. is provided to increase the replenishment capacity of the black developer to increase margin and to prevent the collected used developer from flowing into the deposition chamber too quickly.

〔Example〕

The present invention will be described below based on an embodiment shown in the accompanying drawings.

FIG. 1 is a cross-sectional view showing the overall configuration of the color image forming apparatus of the present application, FIG. 2 is a cross-sectional view showing the configuration of a black developing device, FIG. 3 is a cross-sectional view showing the configuration of another color developing device, and FIG. FIG. 2 is an explanatory diagram showing the relationship between developer flows in a black developing device.

In FIG. 1, reference numeral 1 denotes a flexible photoconductor belt having a photoconductor formed on its surface 1a, and the photoconductor belt 1 is disposed between rotating rollers 2.3 which are mounted on a shaft in a cartridge 30. It is constructed so that it can run clockwise (in the direction of the arrow) by driving the rollers 2.

Reference numeral 4 denotes a guide member, and the guide member 4 is inscribed in the photoreceptor belt 1, and is arranged so that a predetermined tension state can be applied to the belt 1 by a tension roller 5. Thus, the surface 1a of the photoreceptor belt 1 is maintained in a constant positional relationship with respect to the surface of the guide member 4, allowing stable surface image formation.

6 is a charger, and 7 is a laser writing unit serving as an exposure means for forming a latent image. The writing unit 7 is
The laser beam, which is the original image information separated into each primary color,
Polygon mirror 7a, fθ lens 7b, reflection mirror 7C
17d etc., it is possible to form an electrostatic latent image by condensing and scanning light onto the surface 1a of the photoreceptor bell 1.

8.9.10 are C (cyan) and M (magenta) respectively.
, developing device corresponding to Y (yellow), 11 is Bk (black)
The developing devices 8 to 11 are arranged in parallel to face the lower running surface of the photoreceptor belt 1.

The developing units 8 to 11 each include a magnetic developing roller 8a,
9a, 10a.

11a, and developer storage boxes 8b, 9b, 10b, and 11b containing developer Z (a mixture of resin-coated ferrite carrier and color toner) below the developer Z.

A cartridge 30, which is formed by integrating the photoreceptor belt 1 and the developing devices 8 to 11, is configured to be openable and closable or to be detachable from the main body 100.

The developing rollers 8a to lla each correspond to the photoreceptor belt 1.
A magnetic roll J is housed inside a rotating sleeve close to the surface 1a of the belt, and the magnetic attraction force of the magnetic roll J attracts the developer Z, and the rotating sleeve K supplies toner to the belt surface 1a. It is now possible to do so. Then, the electrostatic latent image on the belt surface 1a is converted into a toner image via the rotating sleeve K by a non-contact development method.

A color developing device is shown in FIGS. 3(a) and 5.

The developer storage boxes 8b to 10b are connected to the developing rollers 8a to 1.
It is divided into a developer supply chamber H and a developer adhesion chamber F by a scraping plate R in contact with the lower side of Oa. Here, the blade of the scraping plate R is in contact with the rotating sleeve K of the developing rollers 8a to 10a on the side of the developer supply chamber H, and the scraped developer is configured to fall into the supply chamber H. ing. In addition, stirring screws St and Sz are provided in the developer replenishment chamber H and the developer adhesion chamber F, respectively, so that the replenishment toner and carrier, which are the constituent components of the developer Z, are scraped off by the scraping plate R. The used toner can be circulated between the supply chamber H and the deposition chamber F while being stirred and mixed uniformly. That is, under normal conditions, the toner flowing in from the toner supply ports 8d, 9d and 10d is mixed with the carrier and used toner, as shown in the third figure, and then stirred to form the developer Z, and the developer is deposited from the supply chamber H. Room F
After the developer adheres, the toner replenishment ports 8d to 1
It will circulate to the 0d side. Furthermore, developer discharge ports 8e to 10e are provided at the lower end of the developer adhesion chamber F, respectively, and as described later, after moving the magnetic pole, the stirring screws S1 and S2 are rotated. , Unused developer can be discharged from below (third
Figure (b)).

Note that the toner supply ports 8d to 8lid provided at the top of each developing unit group are also used as developer supply ports for supplying developer in advance.

On the other hand, in the developing device 11 for black toner shown in FIGS. 2 and 4, the lower side of the developing roller lla is connected to the developer replenishing chamber H and the developer adhering chamber F by the scraping plate R in contact with the lower side of the developing roller lla. The developer replenishment chamber H is divided in the same way as the other developing units 8 to 10, but the developer supply chamber H is configured to be wider than the other replenishment chambers. The replenishment chamber H is provided with a partition plate 11f that divides the replenishment chamber H into a fresh developer replenishment path and a used developer recovery path h2. That is, the black developing device 11 has a developer capacity approximately 50% larger than that of the other color developing devices 8 to 10.

The blade of the seeding plate R is connected to the used developer recovery path h2.
It is in contact with the rotating sleeve K of the developing roller lla on its side, and is configured so that the seeded developer falls into the recovery channel h2.

In addition, a stirring screw S is installed in each flow path so that both the developer flows are in opposite directions in the fresh developer replenishment flow path that receives toner from the toner replenishment port lid and in the used developer recovery path h2. +, S4 is provided to prevent mixing of the fresh and used developer streams. That is, the replenished fresh developer flow passes through the replenishment channel by the stirring screw S, is transported by the stirring screw sI in the adhesion chamber F, and adheres to the rotating sleeve K of the developing roller lla, and is further deposited with the used toner. It merges with the developer flow exiting the recovery path h2 and returns to the replenishment flow path together with fresh developer.

In addition, at the lower part of the terminal end of the developer adhesion chamber F of the developing device 11,
It is exactly the same as the other developing devices 8 to 10 in that a developer discharge port lie is provided and unnecessary developer can be discharged by rotating the stirring screw S1.

Here, the magnetic rolls 8a to lla have S on their surfaces.
Equipped with a magnetic field in which poles and N poles are alternately magnetized, the developer Z (
carriers), but a non-magnetic region is formed over an area of approximately 90 degrees at the center angle. That is, in this embodiment, as shown in the second diagram, 4
Magnetic regions M, in which S and N appear alternately every 5 degrees, are formed on 374 (0 to 270 degrees) of the entire surface, and in the remaining 1/4 region, N (270 degrees) → non-magnetized ( 315 degrees) → N (3
60 degrees) is formed. Then, the magnetic rolls 8a to lla cover the non-magnetic region M2,
It is configured so that it can face the toner supply chamber F side during normal times (during development) and the developer adhesion chamber F side when developer is discharged.

That is, during development, the suction force is not applied to the developer Z on the side of the developer supply chamber H, and the used developer scraped off by the scraping plate R is transferred to the developing roller 8a in the supply chamber H. ~l
It is designed to prevent it from re-adhering to the rotating sleeve K of la. When discharging the developer, the discharge ports 8e to 8lie are opened, the magnetic roll is rotated, and the stirring screws S, S are rotated (in the normal direction) while the magnetic field is moved, and the developer adhesion chamber is rotated. The structure is such that the suction force is not applied to the developer Z on the F side so that the discharge of the developer Z can be promoted.

Each developing roller 8a, 9a, 10 of the developing device groups 8 to 11
In the vicinity of a, lla, developer regulating rollers 8c, 9c,
10c and llc are provided so that the amount of developer adhering to the rotating sleeve K can be regulated. Here, the regulating rollers 8C to 11C are provided opposite to the developing rollers 8a to 11a with a small gap G interposed therebetween, and during normal operation (
During development), the developing rollers 8a to 8a entering the gap G
The developer Z on the surface of 11a is regulated to a predetermined height, so that an approximately constant amount of developer can be supplied.

Note that the distance between the gaps G is extremely close to zero.

On the other hand, the regulating rollers 8C to llc are provided with a rotation means X, and are rotated by a predetermined angle during non-operation (during maintenance or non-development) to change the surface facing the developing rollers 8a to lla. It is designed to eliminate clogging. Although various embodiments of the rotating means By driving the arm member A, all the regulating rollers 8c to llc can be rotated at the same time.

Further, the arm member A is configured to be connected to the attachment/detachment mechanism of the cartridge 30 via the protrusion 101 of the main body 100. For example, when the cartridge 30 is opened or closed during maintenance and inspection, each developing roller 8a to ll is automatically
a is rotated to eliminate clogging of the regulating roller 8cm11c.

12 is a transfer device, and 12a is a charge eliminating bar. The transfer device 12
Thus, the toner image on the photoreceptor belt 1 is transferred onto the recording paper P fed from the paper feed cassette 13, and the charge can be removed by the rear charge removal bar 12a. Reference numeral 14 denotes a cleaning device. The cleaning device 14 is for removing a slight amount of toner remaining on the surface 1a of the photoreceptor belt 1 after development, and is composed of a scraping blade 14a and a toner conveying roller 14b. It is provided near the rotating roller 3 inside the cartridge 30.

18 is a fixing device for thermally fixing the toner image on the recording paper P;
9 is a paper discharge roller, and 20 is a paper discharge tray.

In the above embodiment, the color original image data taken in from the image input section is sent to the polygon mirror 7a and fθ lens 7b of the laser writing unit 7.

After the original image is focused and scanned on the surface 1a of the photoreceptor belt 1 by reflection mirrors 7c, 7d, etc. to form an electrostatic latent image, color toner of each color is applied to the latent image by developing units 8-11. Make it adhere. At this time, the developer Z in the developer storage boxes 8b to Ilb is stirred in the developer storage boxes 8b to Ilb.
,,S,,S, (in the case of the developer box 11b) circulates between the replenishment chamber H and the deposition chamber F while being stirred, and in the deposition chamber F, the amount is regulated by the regulating rollers 8c to 11C while the developing rollers 8a to 8a lla, and a toner image is formed by a non-contact development method. Then, in the vicinity of the rotary roller 2, the toner image is transferred onto the recording paper P by the transfer device 2, fixed by the fixing device 18, and then discharged onto the paper discharge tray 20 by the paper discharge roller 19.

At the time of ejection, first, the ejection mode in the image forming apparatus is selected. That is, when discharging the developer Z after a predetermined maintenance period and replacing it with fresh one, the discharge ports 8e-l
ie is opened, and the non-magnetic areas M2 of the magnetic rolls 8b to llb are conveyed by the rotation of the stirring screws SI and S2, with the non-magnetic areas M2 facing the adhesion chamber F side. Then, the developer Z moves within the adhesion chamber F without causing adhesion to the developing rollers 8 to 11, and reaches the developer discharge ports 8e to 11e.
and collected by a predetermined collection means.

During this discharge, control is performed such that only the developing device group is operated simultaneously or selectively in sequence while other drive systems are stopped. Further, the developing roller may be stopped.

〔Effect of the invention〕

As described above, the present invention includes a magnetic developing roller and a developer box that is divided into a developer supply chamber and a deposition chamber by a developer scraping plate, and in which the developer can be circulated by a stirring screw in each chamber. In a color image forming apparatus in which a group of developing devices are arranged in parallel below a photoreceptor belt, a developer replenishing chamber of a predetermined developing device among the developing devices is configured to be wider than other replenishing chambers; A partition plate is installed to divide the replenishment chamber into a fresh developer supply path and a exhausted used developer recovery path, and each flow is designed so that the developer flow supplied with toner and the developer flow with reduced toner concentration are in opposite directions. Since it is characterized by a stirring screw installed in the path, it increases the toner capacity of the frequently used black developer, eliminating the risk of running out of supply, and prevents scraped and exhausted developer from flowing into the adhesion chamber. You can do it like this.

As a result, it is possible to prevent various troubles related to the black developing device from occurring with a simple configuration, and to provide a color image forming apparatus that achieves stable image quality and improved operational reliability. .

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of the color image forming apparatus of the present application, FIG. 2 is a cross-sectional view showing the configuration of a black developing device, FIG. 3 is a cross-sectional view showing the configuration of another color developing device, and FIG. 5 is an explanatory diagram showing the relationship between the developer flow in the black developing device, and FIG. 5 is a principle diagram showing the relationship between the developer discharge port and the developer flow. 1 - Photosensitive belt 2.3 - Rotating roller 4 - Guide member 5 - Tension roller 6 - Charger 7 - Laser writing unit developer 1a 1b 1c id ie 8, 9, 10, 11 8a, 9a, 10a, 8b, 9b, 10b, 8c, 9c, 10 cl 8d, 9d, 10d. 8e, 9e, 10 el 11f - Partition plate 12 - Transfer device 12a - Static neutralizer 13 - Paper feed cassette 14 - Cleaning device 14a - Scraping blade 14 b --- Toner transport roller 18 Fixed applicator 19 - Paper discharge roller 20-Paper output tray 30-Cartry/7ji 100-Main body 101-Protrusion A---Arm member Developing roller Developer storage box regulating roller Toner supply port Developer discharge port C-Clutch F-Toner adhesion chamber G-- - Gap H - Developer supply chamber hl - Fresh developer flow path h2 - Used developer flow path J - To the magnetic roll - Rotating sleeve Ml - Magnetic area M2 - Non-magnetic area P - Recording paper R - Sweeping plate s,, SZ, 33, S, - Stirring screw X...-
Rotating means z - Developer patent Applicant: Konica Corporation

Claims (1)

[Claims] A developing device group equipped with a magnetic developing roller and a developer storage box that is divided into a developer supply chamber and a developer adhesion chamber by a developer scraping plate, and in which the developer can be circulated by a stirring screw in each chamber. In a color image forming apparatus, a developer replenishing chamber of a predetermined developing device among the developing devices is configured to be wider than other replenishing chambers, and the replenishing chamber is used for fresh development. A color that is characterized in that a partition plate is provided to separate the developer supply path and the used developer recovery path, and a stirring screw is provided in each flow path so that the flow of replenishing developer and the flow of recovered developer are in opposite directions. Image forming device.