JPH117183A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of dealing with locally massive consumption of a toner by a single developing device. SOLUTION: A developing device 12 contained in this device is provided with a developing roller 26 for bringing a developer in contact with a photoreceptor 10. A first toner replenishing section 18 is provided with a first replenishing roller 46 and the developer is replenished to a developing vessel by this first replenishing roller 46. Moreover, the developing device 12 is provided with a second toner replenishing section 20 and a toner is replenished to the first toner replenishing section 18 by plural toner replenishing devices provided thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, and more particularly to a developing apparatus for use in an electrophotographic image forming apparatus for visualizing an electrostatic latent image formed on a photoreceptor. About.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, for example, a copying machine or a printer, a process of forming an electrostatic latent image on a photoreceptor and visualizing the electrostatic latent image with a powder toner is performed.
In such an image forming apparatus, since the electrostatic latent image is formed with a predetermined width in a direction orthogonal to the rotation direction of the photoconductor (photoconductor axis direction), the density of the image to be generated is reduced in all regions. In order to maintain the value at or above a predetermined value, the toner must be uniformly contacted with the photosensitive member in its axial direction.

On the other hand, in copiers and printers, when a large number of original images including a solid image such as a photograph are printed in large quantities,
A large amount of toner is consumed in a specific area on the photoconductor.

In view of the above, an image forming apparatus in which a plurality of developing devices are arranged around a photoreceptor has been proposed as an image forming apparatus which can secure a uniform image density in the axial direction of the photoreceptor and can cope with a large amount of local consumption of toner. Have been.

[0005]

However, arranging a plurality of developing devices around the photoreceptor increases the size of the image forming apparatus, and contradicts the demand for downsizing.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of coping with local mass consumption of toner with a single developing apparatus. A developing tank for housing at least one rotating member extending in a first direction orthogonal to the rotation direction of the photoconductor in order to bring the developer into contact with the photoconductor, and bringing the developer into contact with the photoconductor according to the rotation of the rotating member Having. The developing device also has a first replenishing unit arranged along the first direction, and has a first developer replenishing unit for replenishing the developing tank with the first replenishing unit by the first replenishing unit. A plurality of second replenishing units disposed along the direction of the first direction, and a second developer replenishing unit for replenishing the first developer replenishing unit with the plurality of second replenishing units. Have.

[0007]

In the developing device described above, the replenishing developer is stored in the second developer replenishing section. This developer
The first developer replenishing unit is replenished by a plurality of second replenishing means. Next, the developer in the first developer supply section is supplied to the developing tank by the first supply means. When replenishing the developer from the second developer replenishment unit to the first developer replenishment unit, if only a specific replenishment unit is driven out of the plurality of second replenishment units, the first developer replenishment unit receives the first developer replenishment unit. The developer is supplied only to an area corresponding to the driven supply means. Therefore, when a large amount of the developer is consumed in a specific area on the photoconductor, the second replenishing unit corresponding to this is driven to increase the replenishment amount of the developer in the specific area.
Therefore, the developer is uniformly supplied to the photoconductor in all the areas including the specific area, and an image without density unevenness is obtained.

In the developing device, the first developer replenishing section includes a plurality of developers arranged at predetermined intervals in the first direction in order to detect a distribution of the developer amount in the first direction. Preferably, an amount detecting means is provided, and the plurality of second replenishing means are selectively driven based on a detection result of the corresponding developer amount detecting means. In this embodiment, the developer can be supplied in consideration of the developer amount distribution in the first developer supply section.

In the second developer replenishing section, the same number of second replenishing means are respectively provided in left and right regions divided by a center line passing through the central portion of the photoreceptor and extending in a second direction orthogonal to the first direction. Are preferably driven simultaneously. In the present embodiment, extreme bias of the developer in the first developer supply unit is eliminated, and the image density of the entire image can be appropriately maintained.

In the first direction, a plurality of developer adhering amount estimating means for estimating the amount of the developer adhering to the photoreceptor are provided. Preferably, the second replenishing means is selectively driven. In the present embodiment, since the developer is supplied after estimating the actual amount of the applied developer, an image having a further appropriate density can be obtained.

The plurality of second replenishing means are provided corresponding to the plurality of openings arranged in the first direction and the respective openings, and the first developer replenishing unit is provided through the openings. May be constituted by a plurality of developer replenishing members for replenishing the developer, or one opening formed along the first direction, and arranged along the opening, through the opening. And a plurality of developer supply members for supplying the developer to the first developer supply section.

The first replenishing means may comprise a plurality of developer replenishing members arranged in a first direction.

[0013]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a part of a photoconductor 10 and a developing device 12 included in an electrophotographic image forming apparatus according to the present invention. The photoreceptor 10 can be driven to rotate at a constant speed in the direction of arrow 14. The developing device 12 is generally
A developing tank 16 containing a two-component developer composed of a toner and a carrier, a first toner replenishing unit 18 for replenishing the developing tank 16 with toner, and a first toner replenishing unit 18 for replenishing toner to the first toner replenishing unit 18 And two toner supply units 20.

The developing tank 16 accommodates a developing roller 26 which faces the photoreceptor 10 in a developing area 24. The developing roller 26 is rotatable in the direction of arrow 28. A magnet 30 is housed inside the developing roller 26, and the developer can be held on the outer periphery of the developing roller 26 by a magnetic field formed by the magnet 30.
A developer regulating plate 32 is opposed to the upper outer peripheral surface of the developing roller 26 at a predetermined minute interval, so that the amount of the developer conveyed by the developing roller 26 is adjusted. A first stirring roller 34 is accommodated on the opposite side of the developing region 24 with the developing roller 26 interposed therebetween so as to be rotatable in the direction of the arrow 36. The rotation of the first stirring roller 34 mixes the toner and the carrier. And are charged to opposite polarities. On the opposite side of the developing roller 26 with the first stirring roller 34 interposed therebetween, a second stirring roller 38 is disposed so as to be rotatable in the direction of arrow 40, and mixes the developer with the first stirring roller 34. The charge amount of the toner and the carrier is increased by stirring.

The first toner supply section 18 has a first toner container 42. The first toner container 42 has a supply port 44 that connects the developing tank 16 and the first toner container 42 above the first stirring roller 34. The supply port 44 extends in a first direction parallel to the axial direction of the photoconductor 10. In the vicinity of the supply port 44, a first toner supply roller 46 is provided so as to be rotatable in the direction of the arrow 48 so as to close the supply port 44. Inside the first toner container 42, a first toner supply roller 46 is also provided.
A supply blade 50 that conveys toner toward is provided so as to be rotatable in the direction of arrow 52.

As shown in FIGS. 2 and 3, the second toner replenishing section 20 comprises a plurality (four in the present embodiment) of toner replenishers 54 (54A-54D). The toner replenishing units 54 (54A-54D) are respectively fixed units 56 fixed to the main body (see FIG. 1) of the second toner replenishing unit 20.
And a rotation cap 58 rotatably supported by the fixed portion 56, and a toner bottle 60 (60A-60D) containing replenishment toner. The drive mechanism including the motor 62 rotates in the direction of arrow 64. The toner bottle 60 is fixed by inserting its mouth 66 into the rotating cap 58 and rotates with the rotating cap 58. An opening 68 is formed in the toner bottle 60 near the mouth 66 to supply the toner contained in the toner bottle 60. On the other hand, the rotating cap 58
Is formed with a supply port 70 communicating with the opening 68 with the toner bottle 60 attached thereto.
The rotation cap 58 and the toner bottle 6
0, the toner drops from the supply port 70 when the supply port 70 faces vertically downward, and the first toner supply unit 1
8 through a drop port 72 provided above the first toner supply unit 1.
8 is supplied to the toner container 42 in a falling state.

As shown in FIG. 3, the toner replenisher 54 is arranged symmetrically with respect to a center line which is orthogonal to the rotation direction of the photoconductor 10 and passes through the center of the photoconductor 10.
A plurality of toner amount detectors 74 (74A-74D) are provided at the bottom of the toner container 42 in the first toner replenishing section 18 corresponding to the plurality of toner replenishers 54. The toner amount detector 74 may be a pressure sensor that detects the weight of the toner on the toner sensor, or may be a device that detects the remaining amount of toner in a combination of an optical sensor and the optical sensor.

Each toner amount detector 74 is provided with a replenishment control device 76.
Is electrically connected to The supply control device 76 is connected to the motor 62 of each toner supply device 54. The replenishment control device 76 drives the motor 62 in accordance with a predetermined program based on the output of the toner amount detector 74, and sends a predetermined amount of toner from each of the toner replenishers 54 to a corresponding portion of the first toner replenishment unit 18. The toner is dropped and supplied.

In the developing device 12 configured as described above,
The developer contained in the developing tank 16 is mixed and stirred by the rotation of the first stirring roller 34 and the second stirring roller 38, and the toner and the carrier are respectively charged to opposite polarities. Further, the developer stirred by the first stirring roller 34 is supplied to the developing roller 26 and is held on the outer peripheral surface of the developing roller 26 by the magnetic force of the magnet 30. Next, after the transport amount of the developer is adjusted by the regulating plate 32, the developer comes into contact with the outer peripheral surface of the photoconductor 10 in the developing area 24, and the toner is applied to the electrostatic latent image formed on the outer peripheral surface of the photoconductor 10. To form a visible image.

As described above, when the toner is consumed and the density of the created image becomes lower than a predetermined value, the first
The toner replenishing roller 46 and the supply blade 50 of the toner replenishing section 18 rotate, and the toner is replenished to the developing tank 16. In the present embodiment, the toner supply roller 46 has a length substantially corresponding to the width (length in the axial direction) of the photoconductor 10, and the toner is uniformly distributed in the axial direction of the photoconductor in the toner container 42. As long as the toner is supplied to the developing tank 16 in the same direction.

In the first toner supply section 18, the toner distribution state (or empty state) in the toner container 42 is detected by a toner amount detector 74. When it is determined that the toner amount (toner level) of a specific portion is lower than a predetermined value, the toner replenishing device 54 corresponding to the region is driven to supply a necessary amount of toner to the portion. . Therefore, the toner container 42 of the first toner replenishing unit 18 always stores a certain amount or more of toner in all areas thereof, and replenishes the toner uniformly from the first toner replenishing unit 18 to the developing tank 16. can do.

The structure of the second toner supply section 20 is not limited to the above embodiment. For example, FIGS. 4 and 5 show another form of the toner replenishing unit 20, and the second toner replenishing unit 20 includes a plurality of toner replenishers 80. A screw-type conveyor 82 is provided at the bottom of the second toner replenishing machine 80.
The toner is sent out by each conveyor 82 based on the driving of the motor 84. On the other hand, an opening 86 is formed in the first toner replenishing section 18 at a toner drop position of the conveyor 82, and
The toner conveyed in 2 is dropped and supplied to the first toner supply unit 18 through the opening 86. In the present embodiment, the toner amount of each part of the second toner replenishing unit 20 is detected by the toner amount detector 74, and based on the detection result, the control device 76 drives the corresponding motor 84 and the conveyor 82 An appropriate amount of toner is supplied to each part.

The toner replenishers 54 and 80 of the second toner replenishing section 20 may be driven based on image information created by the image forming apparatus. For example, in the digital image forming apparatus, the controller 76 determines the image black-and-white ratio or toner consumption (FIG. 6B) of the area assigned to each toner replenisher 54 or 80 from the image data to be created (FIG. 6A).
And the toner replenisher 54 or 80
Drive and drive time are set.

On the other hand, in the case of an analog type image forming apparatus, a plurality of reflection sensors are provided on the side of the photoconductor 10 in the axial direction of the photoconductor 10, thereby detecting the amount of toner adhered to the photoconductor 10. The same operation and effect can be obtained by measuring the toner consumption amount and selectively driving the plurality of toner replenishers 54 or 80 based on the result.

In the above description, the second toner supply unit 20
Provided with a plurality of toner replenishers 54 or 80 in the axial direction of the photoreceptor 10, but as shown in FIG. 7, one toner replenishing roller 90 extending in the longitudinal direction of the photoreceptor 10 is provided. The toner may be dropped from the toner supply unit 20 to the first toner supply unit 18.

The first toner supply roller 46 and / or
Alternatively, the second toner supply roller 90 may be divided into a plurality of small rollers, and these small rollers may be selectively driven. In this case, as described above, it is preferable to drive the same number of rollers in the left and right regions with respect to the line passing through the central portion of the photoconductor 10 and orthogonal to the axis of the photoconductor 10.

The toner supply control of the developing device 12 will be described. 8 and 9 show the toner amount detector 74 (74A-
FIG. 74D shows supply control for driving the toner supply motor 62 in accordance with the detection result. In this replenishment control, it is determined whether or not toner is present in the toner bottle 60, and if there is no toner, a warning is issued. Instead of the warning, the developing device or the image forming device may be deactivated. On the other hand, when there is toner in the toner bottle 60, the toner amount detector 74 (74A-74)
Based on the detection result of D), it is determined whether or not a predetermined amount of toner is present in an area of the first toner supply unit 18 to which each of the toner amount detectors 74 (74A-74D) is allocated (whether or not the toner is empty). If it is determined that there is no predetermined amount of toner, the corresponding toner supply motor 62 is driven to supply toner to the corresponding area.

FIGS. 10 and 11 show another toner supply control. In this toner supply control, the toner amount detector 74 (74A-
If a predetermined amount of toner is not present in the area to which 74D) is assigned, the corresponding toner supply motor 62 is driven to drive the second toner supply unit 20 to the first toner supply unit 1.
8, the toner supply roller 46 is driven to supply toner to the developing tank 16.

FIGS. 12 and 13 correspond to FIGS.
Modifications 0 and 11 are shown, in which toner supply is controlled based on image data of the image forming apparatus. That is,
If there is an image with high toner consumption in a specific area,
From the image data, it is determined which of the toner replenishers is assigned to the specific area, and based on the result, the corresponding toner replenisher motor is driven to supply toner.

The toner replenishment control shown in FIG. 14 determines whether or not there is toner in the bottle corresponding to the case where the toner shortage is detected by the toner amount detector 74, and drives the toner replenisher based on the determination result. Things. In this supply control, for example, when toner shortage is detected by the toner amount detector 74A at the end, first, it is determined whether or not there is toner in the corresponding bottle 60A, and if there is, toner is supplied from the bottle 60A. However, if there is no toner in the bottle 60A, it is determined whether there is toner in the next bottle 60B, and if there is no toner there, it is determined whether there is toner in the next bottle 60C. Replenish.

However, the toner amount detector 74B other than the end portion
When it is determined that the predetermined amount of toner does not exist in FIG.
As shown in FIG. 6, when a toner shortage is detected by the toner amount detector 74B, first, it is determined whether or not there is toner in the corresponding bottle 60B.
Supply toner from 0B. However, if there is no toner in the bottle 60B, it is determined whether or not there is toner in the adjacent bottles 60A and 60C. If there is toner in these bottles, the toner is supplied from both the bottles 60A and 60C. However, if there is no toner in one of the bottles, the toner is replenished from the bottle 60A or 60C where the toner exists and another bottle 60D. However, if there is no toner in any of the bottles 60A and 60C, the toner is supplied from the remaining bottle 60D.

It should be noted that whether or not toner should be supplied is determined based on whether or not there is an image with a large amount of toner consumption in the corresponding area of the toner amount detectors 74A-74D from the image data. Similarly, toner may be supplied (see FIGS. 15 and 17).

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a developing device mounted on an image forming apparatus according to the present invention.

FIG. 2 is an exploded perspective view of a toner replenishing machine in a second toner replenishing unit provided to the developing device.

FIG. 3 is a diagram illustrating toner supply of a second toner supply unit.

FIG. 4 is a perspective view of another embodiment of a toner supply device in a second toner supply unit.

FIG. 5 is a view for explaining toner supply by a second toner supply unit shown in FIG. 4;

FIG. 6 is a diagram showing a relationship between a document image (A) and a toner consumption amount (B) when the document image is developed.

FIG. 7 is a diagram illustrating another embodiment of the second toner supply unit.

FIG. 8 is a block diagram of a toner supply control circuit.

FIG. 9 is a flowchart of toner supply control.

FIG. 10 is a block diagram of another embodiment of the toner supply control circuit.

11 is a flowchart of the toner supply control circuit shown in FIG.

FIG. 12 is another toner supply control circuit diagram.

FIG. 13 is another toner supply control circuit diagram.

FIG. 14 is a flowchart of control for selecting a toner supply device.

FIG. 15 is a flowchart of control for selecting a toner supply device from image data.

FIG. 16 is another flowchart of control for selecting a toner supply device.

FIG. 17 is another flowchart of control for selecting a toner supply device from image data.

[Explanation of symbols]

10 photoconductor, 12 developing device, 16 developing tank, 18
First toner supply unit, 20... Second toner supply unit.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshifumi Watanabe 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Shinya Matsuura Inventor Shinya Azuchi-cho, Chuo-ku, Osaka-shi 2-3-13 Osaka International Building Minolta Co., Ltd.

Claims (7)

[Claims] In an electrophotographic image forming apparatus, a developing device for visualizing an electrostatic latent image formed on a rotating photoconductor is provided in order to bring a developer into contact with the photoconductor. A developing tank which accommodates at least one rotating member extending in a first direction orthogonal to the rotating direction of the developer, contacts the developer with the photosensitive member in accordance with the rotation of the rotating member, and is arranged along the first direction. A first developer replenishing unit having a first replenishing unit for replenishing the developer to the developing tank with the first replenishing unit; and a plurality of second replenishing units arranged along the first direction. A second developer supply unit that supplies the first developer supply unit with the developer by the plurality of second supply units;
An image forming apparatus comprising: A first developer supply unit configured to detect a plurality of developer amounts detected at predetermined intervals in the first direction in order to detect a developer amount distribution in the first direction; 2. The image forming apparatus according to claim 1, further comprising: means for selectively driving the plurality of second replenishing means based on detection results of the plurality of developer amount detecting means. 3. The same number of second replenishers are simultaneously driven in left and right regions divided by a center line passing through a central portion of the photoconductor and extending in a second direction orthogonal to the first direction. 2 image forming apparatus. 4. A plurality of developer adhering amount predicting means for estimating an amount of developer adhering to the photoreceptor in the first direction, wherein the plurality of developer adhering amount estimating means are provided in accordance with a result of the developer adhering amount estimating means. 4. The method according to claim 2, wherein the second supply means is selectively driven.
Image forming apparatus. 5. The plurality of second replenishing means are provided corresponding to each of a plurality of openings arranged in a first direction and the first developer via the openings. The image forming apparatus according to claim 1, further comprising a plurality of developer supply members that supply the developer to the supply unit. 6. A plurality of second replenishing means, one opening formed along a first direction, and arranged along the opening, and a first developing means provided through the opening. The image forming apparatus according to claim 1, further comprising a plurality of developer supply members configured to supply the developer to the developer supply unit. 7. The image forming apparatus according to claim 1, wherein said first replenishing means comprises a plurality of developer replenishing members arranged in said first direction.