JP3010585B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device of an image forming apparatus using an electrophotographic technique, such as a copying machine and a laser beam printer.

(Prior Art) Conventionally, in an image forming apparatus such as a copying machine, an electrostatic latent image formed on a photosensitive drum serving as an image carrier is developed using a developer (a toner only or a mixture of a magnetic material and a toner). A developing device is incorporated which develops the electrostatic latent image into a toner image by developing the electrostatic latent image into a toner image.

The developing device generally has a developing sleeve which is a developer carrying member, a developing unit for supplying the developer toward the photosensitive drum, and a fixed amount of the developer, and the internal developer is supplied via a stirring member. And a developer container to be supplied to the developing unit. The developing device is removably provided in the main body of the image forming apparatus. When the developer in the developer container runs out, the developing device can be replaced with a new one.

By the way, in a developing device having a configuration in which a developer is generally pumped and supplied from a developer container to a developing unit, a stirring member in the developer container has a function of stirring the developer and a function of conveying the developer to the developing unit. Because it is necessary to combine
As the stirring member, a plate-like member capable of transporting the developer without leakage is used.

(Problems to be Solved by the Invention) However, the following problems have occurred in the conventional example.

In other words, the initial density is low, and the density is not stabilized at a high density unless a certain number of sheets are printed (hereinafter, referred to as “rise of the initial density”). there were.

The reason why there is the above-mentioned "rise of the initial density" is that when a plate-shaped stirring member is used, the developer without a tribo is transferred to the developing section by transporting the developer from the developer container section to the developer without leakage. This is because the excess amount of developer causes the triboelectricity of the developer contributing to the development around the developing sleeve to relatively decrease at the beginning.

Also, the reason why the stirring torque is increased is that when a plate-shaped stirring member is used, the resistance pressing force of the developer to the stirring member increases.

The present invention has been made in view of the above problems, and has as its object the occurrence of the phenomenon of “rising initial density” and the occurrence of defects such as uneven density and low density of a portion where the developer is insufficiently supplied to the developing section. It is another object of the present invention to provide a developing device capable of preventing the above problem and reducing the stirring torque of the developer.

(Means for Solving the Problems) In order to achieve the above object, the invention according to claim 1 provides a developer carrying member for carrying a developer, a developer container for containing a developer, and the developer container. A plurality of rotatable stirring members for stirring the developer contained in the portion and conveying the developer to the developer carrier, wherein each stirring member includes a rotating shaft portion and a rotating shaft portion. In a developing device having a single stirring section provided from one end to the other end, a plurality of openings are formed in each of the stirring sections, and each opening is formed in an axial direction of each of the stirring members. Are overlapped with each other.

Further, the invention according to claim 2 is a developer carrying member for carrying a developer, a developer container for containing a developer, and a developer for stirring the developer contained in the developer container. A rotatable stirrer for conveying to the carrier, wherein the stirrer includes a rotary shaft, and a single stirrer provided from one end to the other end of the rotary shaft. In the developing device described above, the stirring portion is provided with an opening formed in a net shape.

(Operation) According to the present invention, since the developer leaks from the opening formed in the stirring member when the developer is stirred by the stirring member, the developer without the triboelectricity is excessively sent to the developing unit. This prevents the occurrence of the so-called “rise of the initial concentration” phenomenon. And, because the plurality of openings formed in each stirring member overlap each other in the axial direction of the stirring member, or because the stirring portion of the stirring member is provided with a mesh-shaped opening, The amount of the developer passing through the opening becomes substantially uniform in the axial direction, and it is possible to prevent the occurrence of problems such as uneven density and low density at a portion where the developer is insufficiently supplied to the developing unit.

Further, as described above, since the developer leaks from the opening of the stirring member, the resistance pressing force of the developer against the stirring member can be reduced, and as a result, the stirring torque of the developer can be reduced.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

1 to 3 are views showing a first embodiment of the present invention. FIG. 1 is a perspective view of a developing device when there is no developer in a process cartridge, and FIG. 2 is a longitudinal section of the process cartridge. FIG. 3 is a front view of a stirring member of the developing device.

In FIG. 2, reference numeral 1 denotes a photosensitive drum serving as an image carrier,
A charging roller 2 and a cleaning blade 3 are in contact with the outer periphery of the roller, and a developing sleeve 4 is provided. Note that a rubber blade 5 is in contact with the outer periphery of the developing sleeve 4.

In FIG. 2, reference numeral 6 denotes a developer container which contains a developer 7 and has a plurality of stirring members 8 for stirring the developer 7 therein. The stirring member 8 is driven to rotate in a direction indicated by an arrow in FIG. 2 by a gear group 10 (see FIG. 1) meshing with a gear (not shown) connected to one end of the photosensitive drum 1.

By the way, in this embodiment, as shown in FIG. 2, each stirring member 8 has the same phase in the rotation direction from the one end to the other end of the rotating shaft 8A and the rotating shaft 8A. And one plate-shaped agitating section 8B provided in the main body. As shown in FIG. 1 and FIG. 3, a plurality of openings 8a are formed obliquely on one side of the stirring member 8, and openings 8b inclined in the opposite direction to the openings 8a are formed on the other side. Are formed.

Therefore, when the developer 7 is conveyed from the developer container to the developing unit by the stirring member 8, the developer 7 leaks through the openings 8a and 8b formed in the stirring unit 8B of the stirring member 8. become. As a result, the developer 7 having no tribo is not excessively fed to the developing section, and the tribo around the developing sleeve 4 can be prevented from lowering. Can be effectively prevented.

Further, since the developer 7 leaks through the openings 8a and 8b, the resistance pressing force of the developer 7 against the stirring member 8 can be reduced, and the stirring torque can be reduced.

Thus, in the present embodiment, as shown in FIG. 3, the openings 8a and 8b are formed so as to overlap each other in the axial direction (the direction of the arrow in the drawing). That is,
In FIG. 3, two openings 8a adjacent on a broken line XX
(8b) The end competitors overlap each other. By doing so, the amount of the developer passing through the openings 8a and 8b becomes substantially uniform in the axial direction, and the occurrence of problems such as uneven density and low density at a portion where the developer is insufficiently supplied to the developing section is reduced. Can be prevented.

Furthermore, if the directions of the oblique openings 8a and 8b formed in the stirring member 8 closer to the developing sleeve 4 and the stirring member 8 farther away are made bilaterally symmetric with respect to the broken line XX shown in FIG. The movement of the developer in the developer container 6 can be made uniform, and the deviation of the amount of the transported developer can be eliminated.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a view similar to FIG. 1 showing the second embodiment, and FIG. 5 is a front view of the stirring member. In these figures, the same elements as those shown in FIGS. 1 to 3 are used. Are denoted by the same reference numerals, and description thereof will be omitted below.

In the present embodiment, the stirring member 8 is formed of a net-like plate, in which a number of openings 8a are formed. Note that, also in the present embodiment, the openings 8a overlap each other in the axial direction of the stirring member 8.

Thus, in this embodiment, in addition to the effect obtained in the first embodiment, an effect that the opening 8a can be easily formed is obtained.

Also, as shown in FIG. 5, if a blind member 11 formed with a plurality of openings 11a is adhered on the mesh-like stirring member 8, the development leaks through the openings 8a of the stirring member 8. The amount of agent can be easily controlled.

(Effects of the Invention) As is apparent from the above description, according to the present invention, when the developer is stirred by the stirring member, the developer leaks from the opening formed in the stirring member, so that the development without the tribo is established. It is possible to prevent the agent from being excessively sent to the developing section, and to prevent the so-called “initial rise of the initial density” from occurring.

Also, because the plurality of openings formed in each stirring member overlap each other in the axial direction of the stirring member, or because the stirring portion of the stirring member is provided with a mesh-shaped opening, The amount of the developer passing through the opening becomes substantially uniform in the axial direction, and the effect of preventing the occurrence of problems such as uneven density and low density at a portion where the developer is insufficiently supplied to the developing section can be obtained.

Also, as described above, the developer leaks from the opening of the stirring member, so that the resistance pressing force of the developer against the stirring member can be reduced, and as a result, the effect of reducing the stirring torque of the developer can be obtained. can get.

[Brief description of the drawings]

FIG. 1 is a perspective view of a developing device when there is no developer in a process cartridge, FIG. 2 is a longitudinal sectional view of the process cartridge, FIG. 3 is a front view of a stirring member, and FIG. FIG. 5 is a view similar to FIG. 1 showing a second embodiment, and FIG. 5 is a front view of a stirring member. 4 developing sleeve (developer carrying member), 6 developer container, 7 developer, 8 stirring member, 8A rotating shaft portion,
8B: stirring section, 8a, 8b, 11a: opening.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Nagata 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Toshihiko Yamanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-64-4778 (JP, A) JP-A-63-35058 (JP, U) JP-A-62-71648 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G03G 15/08-15/09

Claims (2)

(57) [Claims] A developer carrying member for carrying the developer, a developer container for containing the developer, and agitating and transporting the developer contained in the developer container to the developer carrying member. A developing device comprising: a plurality of rotatable stirring members, wherein each of the stirring members includes a rotation shaft portion, and a single stirring portion provided from one end side to the other end side of the rotation shaft portion. In the developing device, a plurality of openings are formed in each of the stirring units, and the openings overlap each other in an axial direction of each of the stirring members. 2. A developer carrying member for carrying a developer, a developer container containing the developer, and a developer contained in the developer container being stirred and transported to the developer carrying member. A developing device comprising: a rotatable stirring member, wherein the stirring member includes a rotating shaft portion and a single stirring portion provided from one end to the other end of the rotating shaft portion. A developing device, wherein the stirring portion is provided with a net-shaped opening.