JP2002072688A - Developing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing apparatus having proper toner concentration in an image forming area and making the deviation of the toner concentration in the axial direction of a developer carrier small. SOLUTION: This developing apparatus self-controlling the toner concentration with a small amount of developer is equipped with a 1st regulating member 2 and a developer storing part 3 in which the developer scraped off by the 1st regulating member 2 is stored, and is further provided with a peeling member 13 for peeling developer and toner carried on a developer carrier 1 from the developer carrier 1 by bringing the peeling member 13 into contact with or close to the developer carrier 1 in the developer storing part 3. A rib 14 is provided in an area surrounded by the 1st regulating member 2, the developer carrier 1 and the peeling member 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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 and a laser beam printer.

[0002]

2. Description of the Related Art Hitherto, there has been known a developing device which does not require a toner density (weight percentage of toner contained in a developer) detecting means and controls the toner density by using a magnetic toner. In these developing devices, the amount of taken-in toner differs between a portion where the developer movement is active and a portion where the developer is not active, or a portion where the amount of the developer is large and a portion where the amount of the developer is small. Band-like density unevenness and wavy density unevenness) are likely to occur. For this purpose, attempts have been made to stabilize the toner density by improving the mechanism of the toner take-in section, thereby realizing a more stable and uniform image density.

FIG. 4 is a schematic diagram showing a configuration of a developing device which is an example of the related art. A second regulating member 9 is formed at the lower end of the developer accommodating case 4 and is close to the developer carrier 1. When the toner concentration of the developer is within an appropriate range, the developer is stored in the toner supply path 7. At the position where the toner and the developer are in contact with each other, the toner is not taken in because the developer and the toner do not mix. When the toner is consumed, the bulk of the developer decreases, the developer retaining portion 10 decreases, and the developer circulates below the second regulating member 9. When the toner comes into contact with the circulating portion 11, the toner is taken in by the circulating developer, and when the volume increases, the developer stagnating portion 10 is formed again to interrupt the taking of the toner. 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 a space for circulating the developer formed on the front side thereof, and The relative positional relationship of the toner supply path and the like are optimized to reduce the density unevenness. However, the developer on the developer carrier 1 rotates around without being separated from the developer carrier 1, and there is almost no exchange with the developer forming the developer circulating portion 11. There has been a problem that stress on the carrier becomes extremely large and the charge amount is reduced, and the life of the developer is shortened. Therefore, in the developing device, a rotating developer peeling member 13 is provided near the developer carrier 1 in the developer accommodating case 4 so that the developer is intentionally peeled from the developer carrier 1 and the developer is circulated in the developer circulating section 11. The above problem is solved by exchanging the developer.

[0004]

However, in the above-mentioned prior art, the developer on the developer carrier and the developer in the developer circulating section are exchanged by providing a developer peeling member. Although the deterioration of the carrier is suppressed, the free developer which is not restrained by the magnetic force exists in the area surrounded by the first regulating member, the developer carrier and the developer peeling member, and the When the machine is installed, if there is a height difference between the units in the axial direction, the developer gradually moves from the high side to the low side, and there is a difference in the amount of the developer in the axial direction. In the image density, resulting in a left-right deviation in image density.

In some cases, the developer is mixed in a region surrounded by the first regulating member, the developer carrying member, and the developer peeling member to form an aggregate of the developer. When sandwiched in the gap between the first regulating member and the developer carrying member, the developer in that portion cannot pass between the first regulating member and the developer carrying member, and image formation on the surface facing the image carrying member Since an appropriate amount of developer cannot be obtained in the region, there is a problem that a defective image such as white spots occurs.

Accordingly, the present invention focuses on free developer in a region surrounded by a first regulating member, a developer carrier and a developer peeling member in a developer accommodating chamber, and provides a rib by providing a rib. It is an object of the present invention to provide a developing device that suppresses axial movement and reduces axial toner density deviation.
Further, when the rib is made of a magnetic material, the amount of the 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 appropriate amount in the image forming area is obtained. An object of the present invention is to provide a developing device that prevents the occurrence of a defective image due to a failure in obtaining a developer amount.
It is still another object of the present invention to provide a developing device that prevents the developer on the developer carrier from being peeled off by the ribs, thereby preventing the occurrence of rib marks on an image. Further, the aggregate of the developer formed by mixing the developer in a region surrounded by the first regulating member, the developer carrier and the developer peeling member is broken, and the aggregate is formed by the first regulating member. An object of the present invention is to provide a developing device that prevents a defective image such as a white spot caused by being caught in a gap between a developer and a developer carrier.

[0007]

In order to achieve the above object, the invention according to claim 1 has a magnetic field generating means inside, and carries a two-component developer containing a toner and a magnetic carrier. A developer carrier to be conveyed; a first regulating member for regulating the amount of developer carried and carried by the developer carrier; and a developer accommodating the developer scraped off by the first regulating member. An accommodating portion, a second regulating member disposed upstream of the first regulating member in the direction of transport of the developer on the developer carrier, and a toner carrier adjacent to the developer accommodating portion. And a toner container for supplying the toner. The second regulating member is provided between the developer holding member and the developer holding member when the toner concentration on the developer holding member increases and the layer thickness of the developer increases. With a gap that regulates the flow rate of the developer. In a developing device provided with a peeling member that peels off the developer and toner carried on the developer carrying member from the developer carrying body, an area surrounded by the first regulating member, the developer carrying body, and the peeling member is provided. A developing device with ribs. The invention according to 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, the gap between the rib and the developer carrier is equal to or wider than the gap between the first regulating member and the developer carrier. Equipment. 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 the rib becomes thinner as approaching the developer carrier. According to a fifth aspect of the present invention, there is provided the developing device according to any one of the first to fourth aspects, wherein a diffusion member for diffusing the developer between the ribs is provided.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating 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 developer carrier 1 is rotatably supported around the first and second regulating members 2 and 1 for regulating the layer thickness of the developer. A developer accommodating case 4 forming a developer accommodating portion 3 accommodating the developer blocked by the developer 2 is arranged upstream of the regulating member 2 (in the developing sleeve rotating direction). A toner hopper 6 for storing the toner 5 is disposed adjacent to the developer storage case 4, and the toner hopper 6 and the developer storage section 3 are connected by a toner supply path 7. In the toner hopper 6, there is provided a supply stirring member 8 for feeding the toner 5 toward the supply path while stirring.
A second regulating member 9 is formed at the lower end of the developer accommodating case 4 close to the developer carrier 1. When the toner concentration of the developer (percentage by weight of the toner contained in the developer) is within an appropriate range, the toner is stopped. When the developer 5 is formed in the supply path 7 and the toner 5 contacts the developer, the toner 5 is not taken in because the developer and the toner 5 do not mix. When the toner 5 is consumed, the developer stagnant portion 10 decreases as the bulk of the developer 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 in by the circulating developer, and when the volume increases, the developer stagnant portion 10 is formed again to interrupt the taking of the toner 5. Further, the developer carried and conveyed on the developer carrier 1 is peeled off by a developer peeling member 13 provided in the vicinity of the developer carrier 1, and the developer is circulated by forming a flow along a locus indicated by an arrow A. Mixing and replacement with the developer in the section 11 are performed efficiently. Therefore, only the carrier in the developer entrained by the developer carrier 1 does not deteriorate, and the charging ability can be maintained until the original life of the developer.

An example of conditions for realizing the above operation will be described below. Magnetic poles are alternately arranged inside the developer carrier 1, the magnetic pole facing the image carrier 12 is a P1 pole, P2 and P3 are arranged counterclockwise, and a P4 pole is located at a position facing the developer accommodating section 3. Deploy. The developer circulation part 11
When the predetermined concentration is reached, the arrangement of the P3 and P4 poles and the magnetic force, the position of the second regulating member 9, and the near side thereof are required to cause the developer stagnation portion 10 to appear at the contact portion between the toner 5 and the developer. It is necessary to optimize the shape and position of the space in which the developer to be formed circulates, and the relative positional relationship of the toner supply path 7. FIG. 2 is a diagram showing setting conditions of the machine of the developing device shown in FIG. These conditions are shown using FIG. 2 based on the experimental results.

<Machine setting conditions> P3 pole: θ1 = 127 ° Maximum magnetic flux density in the direction normal to the developer carrier surface: 53 mT P4 electrode: θ2 = 35 ° Maximum magnetic flux density in the direction normal to the developer carrier surface: 56 mT Angle of the second regulating member: θ3 = 14 ° Angle formed by the vertical surface of the second regulating member facing the developer carrier: θ4 = 24 ° Angle formed by the first regulating member and the developer peeling member: θ5 = 3
9 ° Distance between the downstream end of the second regulating member and the surface of the developer carrying member:
a = 0.6 (mm) Opening width of toner supply path: b = 5.5 (mm) Diameter of developer carrier: c = φ16 (mm) Distance between developer peeling member and developer carrier surface: d = 0 .3
(Mm) (developer) Carrier: Material: magnetite or iron Average particle size: 40 to 50 μm Toner: Magnetic substance (magnetite) amount: 15 to 40 wt% Average particle size: 7.5 μm Silica amount: 0.5 to 1. 0% by weight Covering ratio of toner to carrier: 50 to 120% Toner concentration: Approx. 10% by weight Toner charge amount Q / M: 10 to 30 μc / g It is possible to operate under the above condition setting and stable toner concentration of developer. Can be done. The operation can be reproduced under another condition by combining these conditions, and the above condition is an example.

The present invention relates to a developing device used in a developing section of an image forming apparatus such as a copying machine, a laser beam printer, etc., which are used in an environment having a height difference in the axial direction of the developing device. Must also be considered. When used in an environment having a height difference in the axial direction, free developer that is not restrained by magnetic force existing in a region surrounded by the first regulating member 2, the developer carrying member 1, and the developer peeling member 13 is removed. It moves to a relatively low side, and as a result, the developer amount deviation in the axial direction of the developer circulating portion 11 is promoted, so that the toner 5 is not taken in uniformly in the axial direction.
This appears as a toner density deviation in the axial direction. Therefore, FIG.
As shown in FIG. 1, ribs 14 (hatched 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 difference in height in the axial direction, the two ribs 1
Since the height difference in the section sandwiched by 4 is very small, there is no significant difference between the developer amounts on the high side and the low side. for that reason,
In a section sandwiched between the two ribs 14, a good image having no image density deviation can be always printed 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.

Since the ribs 14 are made of a non-magnetic material, a developer bridge is not formed between the ribs 14 and the developer carrier 1 or between the ribs 14 and the developer peeling member 13 and the developer is circulated. Or the developer is restricted by the regulating member 2.
Hinders passing through. The distance between the rib 14 and the developer carrier 1 is set to be equal to or larger than the distance between the first regulating member 2 and the developer carrier 1, so that the rib 14 passes through the first regulating member 2. The amount of the developer on the developer carrier 1 after the processing is uniform in the axial direction, and the occurrence of a defective image such as the appearance of a rib mark on the image can be prevented. Here, the interval between the ribs and the interval between the rib and the developer carrier 1 are set to appropriate values according to the magnetic force of the developer carrier 1 and the type of the developer.

Further, the first regulating member 2 and the developer carrier 1
The developer conveyed by the developer peeling member 13 and the developer regulated by the first regulating member 2 and rising along the regulating member 2 are mixed in a region surrounded by the developer and the developer removing member 13. Aggregates of the developer may be formed due to the matching. When those aggregates are caught in the gap between the regulating member 2 and the developer carrier 1, the developer carried on that portion of the developer carrier 1 cannot pass through the regulating member 2, and the image An appropriate amount of developer cannot be secured in an image forming area which is a surface facing the carrier 12, and a defective image such as a white spot occurs. Therefore, by disposing the comb-shaped developer diffusion member 15 between the ribs 14, the formation of the aggregate of the developer 1 is prevented, and at the same time, the aggregate formed in a place other than the above-described region is prevented. 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 diffusion member. Developer diffusion member 1
5 is not limited to a comb shape, and a thread shape or a mesh shape can be appropriately selected.

[0014]

As described above, in the developing device according to the first aspect, there is no difference in toner density in the section between the two ribs, and there is no difference in elevation in the axial direction of the developing device. Even when used, a good image without any image density deviation can always be printed. The developing device according to claim 2, wherein the rib is made of a non-magnetic material, so that
Between the developer and the developer release member,
Alternatively, a good image having no image density deviation can always be printed without forming a bridge of the developer so as to prevent the developer from passing through the regulating member. In the developing device according to the third aspect, the amount of the developer on the developer carrier after passing through the first regulating member becomes uniform in the axial direction, and the occurrence of a defective image such as the appearance of a rib mark on the image can be prevented. . In the developing device according to the fourth aspect, compared with a developing device in which the rib is not provided with such a shape, the amount of peeling of the developer on the developer carrier is small, and the rib mark is prevented from appearing on the image. be able to. In the developing device according to the fifth aspect, at the same time as preventing the formation of the aggregates of the developer, the aggregates formed in a place other than the above-described region are broken to prevent the occurrence of defective images such as white spots. To prevent.

[Brief description of the 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 setting conditions of a machine of the developing device illustrated in FIG. 1;

FIG. 3 is a schematic view illustrating a shape of a developer diffusion member.

FIG. 4 is a schematic diagram illustrating a configuration of a developing device that is an example of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developer carrier 2 first regulating member 3 developer accommodating section 4 developer accommodating case 5 toner 6 toner hopper 7 toner replenishing path 8 replenishment stirring member 9 second regulating member 10 developer retaining section 11 circulation section 12 image Carrier 13 Developer stripping member 14 Rib 15 Diffusion member A Flow of developer P1, P2, P3, P4 Magnetic pole

Claims (5)

[Claims] 1. A developer carrier having a magnetic field generating means therein for carrying and transporting a two-component developer containing a toner and a magnetic carrier, and a developer carried and transported by the developer carrier A first regulating member for regulating the amount of the developer, a developer accommodating section for accommodating the developer scraped off by the first regulating member, and a transfer of the developer on the developer carrier more than the first regulating member. A second regulating member disposed on the upstream side in the direction, and a toner accommodating portion that is adjacent to the developer accommodating portion and supplies the toner to the developer carrying member. The second regulating member includes a developer carrying member. A gap that regulates the increase in the layer thickness of the developer due to an increase in the toner concentration on the developer carrier when the toner concentration on the developer carrier is increased. Bring them closer together
In a developing device provided with a peeling member that peels off the developer and toner carried on the developer carrying member from the developer carrying body, an area surrounded by the first regulating member, the developer carrying body, and the peeling member is provided. A developing device comprising a rib. 2. The developing device according to claim 1, wherein the rib is made of a non-magnetic material. 3. The gap according to claim 1, wherein a gap between the rib and the developer carrier is equal to or larger than a gap between the first regulating member and the developer carrier. Developing device. 4. The developing device according to claim 1, wherein the rib becomes thinner as approaching the developer carrier. 5. The developing device according to claim 1, further comprising a diffusion member for diffusing the developer between the ribs.