JP4004007B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a developing device used in a developing process of an image forming apparatus such as a copying machine or a laser beam printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a developing device is known that uses a magnetic toner to control a toner concentration without requiring a toner concentration (weight percentage of toner contained in a developer) detection means. In these developing devices, the amount of toner taken in is different at locations where the developer moves actively and where it is not, or where there is a lot of developer, and where the toner density is unstable. Band-like density unevenness and wavy density unevenness) are likely to occur. For this reason, attempts have been made to achieve a more stable and uniform image density by stabilizing the toner density by improving the mechanism of the toner intake section.
[0003]
FIG. 4 is a schematic diagram showing a configuration of a developing device as an example of the prior art.
A second regulating member 9 adjacent to the developer carrying member 1 is formed at the lower end of the developer storage case 4 so that when the toner concentration of the developer is within an appropriate range, the developer staying portion in the toner supply path 7 No. 10 is formed and the toner and the developer are in contact with each other, so that the developer and the toner are not mixed, so that the toner is not taken in. When the toner is consumed, the volume of the developer is reduced, the developer retention portion 10 is reduced, and the developer is circulated below the second regulating member 9. When the toner comes into contact with the circulation portion 11, the toner is taken into the circulating developer and when the bulk increases, the developer retention portion 10 is formed again to interrupt the toner take-in. In order to realize such an operation, the pole arrangement / magnetic force of the developer carrier 1, the position of the second regulating member 9, the shape and position of the space for circulating the developer formed on the front side thereof, and By optimizing the relative positional relationship of the toner replenishment path, density unevenness is reduced. However, since the developer on the developer carrier 1 is not separated from the developer carrier 1 and is rotated around the developer carrier 1, there is almost no replacement with the developer forming the developer circulation portion 11. There has been a problem that the stress on the carrier becomes very large and the charge amount is reduced, resulting in a short life as a developer.
Therefore, in the developing device, the developer peeling member 13 that rotates in the vicinity of the developer carrier 1 in the developer storage case 4 is provided to intentionally peel the developer from the developer carrier 1, and in the developer circulation section 11. A device has been devised to eliminate the above problem by replacing the developer.
[0004]
[Problems to be solved by the invention]
However, in the above-described prior art, by providing a developer peeling member, the developer on the developer carrier and the developer in the developer circulation portion are replaced to suppress the deterioration of the carrier in the developer. There will be free developer that is not restrained by magnetic force in the area surrounded by the first regulating member, developer carrier and developer peeling member, and when installing a printer or copier, If there is a height difference in the unit, the developer gradually moves from the high side to the low side, and the amount of developer can be changed in the axial direction, resulting in a difference in toner uptake in the axial direction, resulting in image density. There is a problem that left and right deviations can be made.
[0005]
In addition, a developer aggregate may be formed by mixing the developer in a region surrounded by the first regulating member, the developer carrying member, and the developer peeling member. If the gap between the regulating member and the developer carrying member is sandwiched, the developer in that portion cannot pass between the first regulating member and the developer carrying member, and is appropriate in the image forming area on the surface facing the image carrying member. Therefore, there is a problem that defective images such as white spots are generated because a large amount of developer cannot be obtained.
[0006]
Therefore, the present invention pays attention to the free developer in the region surrounded by the first regulating member, the developer carrier and the developer peeling member in the developer containing chamber, and by providing ribs, It is an object of the present invention to provide a developing device that suppresses the movement and reduces the toner density deviation in the axial direction.
In addition, when the rib is made of a magnetic material, the amount of developer passing through the first regulating member is reduced by the bridge of the developer formed between the developer carrying member and the rib, so that the proper amount in the image forming area is obtained. It is an object of the present invention to provide a developing device that prevents the occurrence of defective images due to the inability to obtain a developer amount. It is another object of the present invention to provide a developing device that prevents the developer on the developer carrying member from being peeled off by the ribs and preventing rib marks from being generated on the image. Further, the developer aggregate formed by mixing of the developer in the region surrounded by the first regulating member, the developer carrying member and the developer peeling member is broken, and the aggregate is the first regulating member. An object of the present invention is to provide a developing device that prevents the occurrence of defective images such as white spots generated by being sandwiched in the gap between the toner and the developer carrying member.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes a developer carrying member having a magnetic field generating means therein and carrying and conveying a two-component developer containing toner and a magnetic carrier, and development. A first restricting member for restricting the amount of developer carried and conveyed by the agent carrier, a developer containing portion for containing the developer scraped off by the first restricting member, and a first restricting member A second regulating member disposed on the upstream side of the developer carrying member in the transport direction of the developer, and a toner containing unit adjacent to the developer containing unit and for supplying toner to the developer carrying member. The second regulating member has a gap between the developer carrying member and the developer carrying member to restrict the increase when the toner concentration on the developer carrying member increases and the layer pressure of the developer increases. The developer container is rotated in contact with or close to the developer carrier, and is carried on the developer carrier. In a developing device provided with a peeling member that peels the developer and toner from the developer carrier, a plurality of ribs are provided at regular intervals in a region surrounded by the first regulating member, the developer carrier, and the peeling member. The developing device is provided so as to protrude from the first regulating member to the peeling member. The invention described in claim 2 is the developing device according to claim 1, wherein the rib is made of a non-magnetic material. According to a third aspect of the present invention, an interval between the surface of the rib facing the developer carrying member and the developer carrying member is an end portion that regulates the amount of the developer of the first regulating member. The developing device according to claim 1, wherein the developing device is equal to or wider than an interval between the developer carrying member and the developer carrying member. According to a fourth aspect of the present invention, there is provided the developing device according to any one of the first to third aspects, wherein an amount of protrusion from the first regulating member decreases as the rib approaches the developer carrying member.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing a configuration of a developing device according to an embodiment of the present invention.
A magnetic field generating means is fixed inside the developer carrier 1, and the first regulator member 2 and the first regulator member that support the developer carrier 1 rotatably around the developer carrier 1 and regulate the layer thickness of the developer. A developer storage case 4 that forms a developer storage portion 3 that stores the developer blocked by 2 is disposed upstream of the regulating member 2 (in the developing sleeve rotation direction). A toner hopper 6 that stores toner 5 is disposed adjacent to the developer storage case 4, and the toner hopper 6 and the developer storage portion 3 are connected by a toner supply path 7. Provided in the toner hopper 6 is a replenishment stirring member 8 for feeding the toner 5 toward the replenishment path while stirring. A second regulating member 9 adjacent to the developer carrier 1 is formed at the lower end of the developer storage case 4 so that the toner concentration of the developer (weight percentage of the toner to be held by the developer) is within the proper range. The developer staying portion 10 is formed in the replenishment path 7 and the toner 5 is not taken in because the developer and the toner 5 are not mixed in the place where the toner 5 and the developer are in contact with each other. When the toner 5 is consumed, as the volume of the developer decreases, the developer retention portion 10 decreases and the developer circulates below the second regulating member 9. When the toner 5 comes into contact with the circulating portion 11, the toner 5 is taken into the circulating developer and when the bulk increases, the developer retaining portion 10 is formed again to interrupt the toner 5 taking-in.
Further, the developer carried and transported on the developer carrier 1 is peeled off by the developer peeling member 13 installed in the vicinity of the developer carrier 1, and the developer is circulated by creating a flow along the path indicated by the arrow A. Efficient mixing and replacement with the developer in the section 11 is performed. Therefore, the charging ability can be maintained until the original life of the developer without deteriorating only the carrier in the developer carried around the developer carrier 1.
[0009]
An example of conditions for realizing the operation as described above will be described below.
The magnetic poles are alternately arranged inside the developer carrier 1 and the magnetic poles facing the image carrier 12 are P1 poles, P2 and P3 are arranged counterclockwise, and the P4 poles are located at positions facing the developer storage unit 3. Deploy. When the developer circulation section 11 takes in the toner 5 and reaches a predetermined concentration, the arrangement and magnetic force of the P3 pole and P4 pole, the magnetic force, It is necessary to optimize the position of the regulating member 9, the shape and position of the space for the developer formed on the front side thereof to circulate, and the relative positional relationship of the toner supply path 7. FIG. 2 is a diagram illustrating machine setting conditions of the developing device illustrated in FIG. 1. Based on the experimental results, these conditions are shown in FIG.
[0010]
<Machine setting conditions>
P3 pole: θ1 = 127 °
Maximum magnetic flux density in the normal direction of the developer carrier surface: 53 mT
P4 pole: θ2 = 35 °
Maximum magnetic flux density in the normal direction of the developer carrier surface: 56 mT
Second regulating member angle: θ3 = 14 °
Angle that the surface of the second regulating member facing the developer carrying member is perpendicular to the vertical direction: θ4 = 24 °
Angle formed by the first regulating member and the developer peeling member: θ5 = 39 °
Distance between downstream end of second regulating member and developer carrier surface: a = 0.6 (mm)
Toner supply path opening width: b = 5.5 (mm)
Developer carrier diameter: c = φ16 (mm)
Distance between developer peeling member and developer carrier surface: d = 0.3 (mm)
(Developer)
Career:
Material: Magnetite or iron Average particle size: 40-50 μm
toner:
Magnetic substance (magnetite) content: 15-40wt%
Average particle size: 7.5 μm
Silica amount: 0.5 to 1.0 wt%
Covering ratio of toner to carrier: 50 to 120%
Toner concentration: about 10 wt%
Toner charge amount Q / M: 10 to 30 μc / g
The operation under the above condition setting is possible and the toner density of the developer can be stabilized.
By combining these conditions, the operation can be reproduced even under different conditions, and the above conditions are examples.
[0011]
The present invention relates to a developing device used in a developing portion of an image forming apparatus such as a copying machine or a laser beam printer. However, it is also considered that they are used in an environment having a height difference in the axial direction of the developing device. There must be. When used in an environment with a height difference in the axial direction, free developer that is not restrained by the magnetic force existing in the region surrounded by the first regulating member 2, the developer carrier 1 and the developer peeling member 13 As a result, the toner 5 is not uniformly taken in the axial direction in order to promote the deviation of the developer amount in the axial direction of the developer circulating portion 11, and as a result, the toner density deviation is caused in the axial direction. Appear. Therefore, as shown in FIG. 1, ribs 14 (shaded portions in FIG. 1) are provided at regular intervals in a portion surrounded by the first regulating member 2, the developer carrier 1 and the developer peeling member 13. Therefore, even if the developing device is used with a height difference in the axial direction, the height difference in the section between the two ribs 14 is very small, so that there is not much difference between the developer amount on the high side and the low side. . For this reason, in a section between the two ribs 14, there is no toner density deviation, and a good image without image density deviation can always be printed even when used in an environment where there is a height difference in the axial direction of the developing device. it can.
[0012]
Since the rib 14 is made of a non-magnetic material, a developer bridge is not formed between the rib 14 and the developer carrier 1 or between the rib 14 and the developer peeling member 13, thereby preventing circulation of the developer. Alternatively, the developer is prevented from passing through the regulating member 2.
Further, since the interval between the rib 14 and the developer carrier 1 is set to be equal to or larger than the interval between the first restriction member 2 and the developer carrier 1, it passes through the first restriction member 2. The amount of the developer on the developer carrier 1 after this is uniform in the axial direction, and the occurrence of defective images such as the appearance of rib marks on the image can be prevented. Here, the interval between the ribs and the interval between the ribs and the developer carrier 1 are set to appropriate values according to the magnetic force of the developer carrier 1, the type of developer, and the like.
[0013]
In the region surrounded by the first regulating member 2, the developer carrier 1 and the developer peeling member 13, the developer conveyed by the developer peeling member 13 and the first regulating member 2 are regulated and regulated. Since the developer that has risen along the member 2 is mixed, an aggregate of the developer may be formed. If these aggregates are sandwiched between the gaps between the regulating member 2 and the developer carrier 1, the developer carried on the developer carrier 1 at that portion cannot pass through the regulating member 2, and the image An appropriate amount of developer cannot be secured in the image forming area that is the surface facing the carrier 12, and a defective image such as white spots occurs. Therefore, by arranging the comb-like developer diffusing member 15 between the ribs 14, the aggregate of the developer 1 is prevented from being formed, and at the same time, the aggregate formed in a place other than the above-described region. On the other hand, they are broken to prevent the occurrence of defective images such as white spots. FIG. 3 is a schematic view showing the shape of the developer diffusing member.
The developer diffusing member 15 is not limited to a comb-like shape, and a thread-like one or a mesh-like one can be appropriately selected.
[0014]
【The invention's effect】
As described above, in the developing device of the present invention, an image density deviation is always maintained even when used in an environment where there is a height difference in the axial direction of the developing device without causing a toner density deviation in a section between two ribs. It is possible to print a good image with no image. In the developing device of the present invention, the rib is made of a non-magnetic material so that the developer is prevented from circulating between the rib 14 and the developer peeling member or the developer is prevented from passing through the regulating member. A good image without any image density deviation can be printed without forming a bridge of the agent. In the developing device of the present invention, the amount of developer on the developer carrying member after passing through the first regulating member is uniform in the axial direction, and the occurrence of defective images such as the appearance of rib marks on the image can be prevented. In the developing device of the present invention, the amount of the developer on the developer carrying member is less peeled than a developing device in which such a shape is not applied to the ribs, and the rib marks can be prevented from appearing in the image. . In the developing device of the present invention, the developer aggregates are prevented from being formed, and at the same time, the aggregates formed at places other than the above-described regions are broken to prevent the occurrence of defective images such as white spots.
[Brief description of drawings]
FIG. 1 is a schematic diagram illustrating a configuration of a developing device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating machine setting conditions of the developing device illustrated in FIG. 1;
FIG. 3 is a schematic view showing a shape of a developer diffusing member.
FIG. 4 is a schematic diagram illustrating a configuration of a developing device which is an example of a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Developer support body 2 1st control member 3 Developer storage part 4 Developer storage case 5 Toner 6 Toner hopper 7 Toner replenishment path 8 Replenishment stirring member 9 Second control member 10 Developer retention part 11 Circulation part 12 Image Carrier 13 Developer peeling member 14 Rib 15 Diffusion member A Developer flow P1, P2, P3, P4 Magnetic pole

Claims (4)

A developer carrier having a magnetic field generating means therein and carrying and transporting a two-component developer containing toner and a magnetic carrier, and the amount of developer carried and carried by the developer carrier are regulated. A first regulating member;
A developer storage portion for storing the developer scraped off by the first restriction member; and a second restriction disposed on the upstream side in the transport direction of the developer on the developer carrier relative to the first restriction member. Members,
A toner container that is adjacent to the developer container and that supplies toner to the developer carrier;
The second regulating member has a gap between the developer carrying member and the developer carrying member to regulate the increase when the toner density on the developer carrying member increases and the layer pressure of the developer increases. In a developing device provided with a release member that rotates in contact with or in close proximity to a developer carrier within the developer container, and peels the developer and toner carried on the developer carrier from the developer carrier.
A development characterized in that a plurality of ribs are provided in a region surrounded by the first regulating member, the developer carrier and the peeling member so as to protrude from the first regulating member to the peeling member with a certain interval. apparatus. The developing device according to claim 1, wherein the rib is made of a nonmagnetic material. The distance between the surface of the rib facing the developer carrier and the developer carrier is the distance between the end of the first regulating member that regulates the amount of the developer and the developer carrier. The developing device according to claim 1, wherein the developing device is equal to or wider than the developing device. 4. The developing device according to claim 1 , wherein an amount of protrusion of the rib from the first regulating member decreases as the developer carrier is approached . 5.

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