JPH03168668A - Developing device - Google Patents

Abstract

PURPOSE:To suppress a developer from clogging by providing a developer escaping port on a position where a space between a supply quantity control member and a bottom developing roller is the narrowest or in the vicinity thereof. CONSTITUTION:The developer is supplied to the bottom developing roller 12 side. When a large quantity of the developer flows into between the roller 12 and the supply quantity control member 16 by the rotation of the roller 12 in the direction of an arrow C, an excessive developer goes to a paddle 15 side through the developer escape port 17 provided on a position where the space between the roller 12 and the member 16 is narrowest. Since the excessive developer is thus pushed out through the developer escaping port in a direction going away from a photosensitive body, developer clogging never arises in the vicinity of the photosensitive body. Therefore, sudden fluctuation in electric charges never arises caused by supplying the large quantity of developer to the photosensitive body side when the developing device is actuated, and prescribed development and copying. Thus, the copying is smoothly carried out. Moreover, the developer is prevented from scattering, as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device provided in an electrostatographic copying machine or the like.

[Conventional technology]

Recently, in order to increase the developing efficiency of the above-mentioned developing device, one in which two developing rollers rotating in different directions are provided in a developing case provided close to the photoreceptor has been put into practical use. It is becoming.

FIG. 4 shows the main parts of such a developing device. In FIG.
2. A developing case disposed close to the surface of the developing device 32, and inside thereof, two developing rollers 33 are placed so as to face the photoreceptor 32.
, 34 are provided. The upper developing roller 33 located above and the lower developing roller 34 located below are horizontally arranged so as to rotate in opposite directions. and,
The rotation direction of the upper developing roller 33 is the same direction of arrow B as that of the photoreceptor 32, and therefore, the upper developing roller 3
3 rotates in a recurved manner so that the moving direction is opposite to that of the photoreceptor 32 at the portion facing the photoreceptor 32 . Further, the rotating direction of the lower developing roller 34 is in the direction of arrow C, which is opposite to that of the photoreceptor 32. Therefore, the lower developing roller 34 moves in the same direction as the photoreceptor 32 in the portion facing the photoreceptor 32. Rotate in parallel directions so that Reference numeral 35 denotes a conveying roller disposed at a position farther from the photoreceptor 32 than the upper developing roller 33, and rotates in the direction of arrow D to transport the two developing rollers 33, 3.
The remaining developer G from No. 4 is sent to an inclined return plate (not shown). Note that these rollers 33, 34. 35 includes a plurality of fixed magnets (in the figure, symbols N,
) are appropriately arranged.

Reference numeral 36 denotes a paddle serving as a developer supplying means for rotating in the direction of arrow E to agitate the developer G containing toner and supplying it to the lower developing roller 34 side, and is provided at the lower inside of the developing case 3l. There is. Reference numeral 37 denotes a supply amount limiting member for limiting the amount of developer G supplied to the lower developing roller 34 side, which forms a predetermined developer passage gap K between its lower end and the inner upper surface of the developing case 3l. In this state, it is provided between the lower developing roller 34 and the paddle 36. In addition to the above-mentioned members, the developing case 31 is provided with a stirring member (not shown) for stirring the toner supplied from the toner supply hopper (not shown) and the developer G from the transport plate. The developer G that has passed through the stirring member is sent in the direction of the paddle 36.

According to the above-mentioned developing device, during the developing operation, the developer G sent out by the paddle 36 rotating in a predetermined direction is limited by a predetermined amount by the supply amount limiting member 37 and is transferred to the lower developing area. It is supplied to the roller 34 side. The developer G passes between an upper developing roller 33 and a lower developing roller 34 that rotate in predetermined rotational directions, and is applied to the photoreceptor 3 by the rotation of both developing rollers 33 and 34.
The electrostatic latent image formed on the surface of the photoreceptor 32 is developed. The remaining developer G that is not used for development returns to the paddle 36 via the conveying roller 35, an inclined return plate (not shown), and a stirring member (not shown), and is used for the next development. [Problems to be Solved by the Invention] However, in the developing device configured as described above, during non-developing operation when the photoreceptor 32 and both copying rollers 33 and 34 are stationary, the problem shown in FIG. 4(A) occurs. As shown, the developer G accumulates in a portion between the lower developing roller 34 and the supply amount limiting member 37 (indicated by the symbol P in the figure), and during development, the developer G is deposited along with the photoreceptor 32 and both the developing rollers 33, 34, etc. When the developing rollers 33 and 34 begin to rotate in a predetermined direction, the developer G accumulated in the portion P is removed as shown in FIG.
As shown in B), both developing rollers 33. 34 and the photoreceptor 32
The developer G is clogged in a portion close to the photoreceptor 32 (indicated by the symbol Q in the figure), and as a result, a large amount of developer G is supplied to the photoreceptor 32 side when the developing device is started, resulting in sudden load fluctuations. In some cases, the specified development process and even the copying process were not carried out. The present invention has been made with the above-mentioned considerations in mind, and an object of the present invention is to provide a developing device that does not cause clogging of developer in the vicinity of a photoreceptor.

[Means to solve the problem]

In order to achieve the above-mentioned purpose, the developing device according to the present invention has the following features:
A feature of the present invention is that a developer escape hole is provided in the supply amount limiting member at or near a position where the distance between the supply amount limiting member and the lower developing roller is the narrowest.

[Effect]

In the developing device according to the present invention having the above-mentioned characteristic structure, at the initial stage of the development operation, the developer is passed between the supply amount limiting member and the lower developing roller through the developer passing gap formed below the supply amount limiting member. Even if a large amount of developer is present, the excess developer is pushed away from the photoreceptor through the developer escape hole provided in the supply amount limiting member, so developer clogging near the photoreceptor is not caused. do not have.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. First, FIG. 2 shows the main parts of an electrostatographic copying machine incorporating a developing device according to the present invention, and in this figure, l is indicated by an arrow A.
It is a photoreceptor that rotates in the direction, and around it is a main charging device 2.
, developing device 3 (detailed structure will be described later), transfer device 4,
A paper separation device 5, a cleaning device 6, etc. are provided. 7 is a mirror that irradiates the surface of the photoreceptor 1 with light from an exposure device (not shown); 8 is a paper supply path that supplies paper from a paper feeder (not shown) toward the photoreceptor 1 at a predetermined timing; 9 is a paper supply path (not shown) This is a paper transport path that transports the paper after transfer and separation to an external fixing device.

The structure of the developing device 3 will be explained with reference to FIG.
IO is a developing case disposed close to the surface of the photoreceptor 1, and two developing rollers 11 and 12 are provided inside the case so as to face the photoreceptor 1. The upper developing roller 11 located above and the lower developing roller 12 located below are configured to rotate in opposite directions. The rotational direction of the upper developing roller 1l is the same direction of arrow B as that of the photoreceptor l. Therefore, the upper developing roller l2 moves in the opposite direction to the photoreceptor l in the portion facing the photoreceptor l. Rotate in the opposite direction so that Further, the rotation direction of the lower developing roller 12 is indicated by an arrow C opposite to that of the photoreceptor l.
Therefore, the lower developing roller 12 rotates in the OI direction so that the moving direction is the same as that of the photoreceptor 1 at the portion facing the photoreceptor 1. Note that both the developing rollers 11
, 12 are assumed to be stopped during non-developing operation when the photoreceptor 1 is stopped. In addition, 13 is an upper developing roller l.
1 is a conveyance roller disposed at a position farther away from the photoreceptor 1, and rotates in the direction of arrow D to transport both the developing rollers 11,
The remaining developer from 12 is sent to an inclined return plate 14. Note that these rollers 11. 12. 13, each has a plurality of fixed magnets (in the figure, symbols N and S
In particular, in the roller 12, six fixed magnets (three each of N and S poles) are arranged alternately N and S so as to divide the circumference into six equal parts. (Details will be explained later). Further, although not shown, fins are appropriately provided upright on the inclined upper surface of the inclined return temporary 14. Reference numeral 15 denotes a developer supplying means which is provided in the lower part of the inside of the developing case IO and rotates in the direction of the arrow E. The paddle is used to stir the developer containing toner and supply it to the lower developing roller 12 side. 16 is a plate-shaped supply amount limiting member for limiting the amount of developer supplied to the lower developing roller 12 side, and is provided between the lower developing roller 12 and the paddle 15, and its upper end side is It extends along the circumferential surface of the roller l3, and its lower end is connected to the developing case I.
A developer passage gap K through which a predetermined amount of developer G passes is formed between the developer passage gap K and the inner upper surface of the developer G. A developer escape hole 17 is formed in the supply amount limiting member 16 at a position where the distance from the lower developing roller 12 is the narrowest, and is inclined slightly upward. More specifically, as shown in FIGS. 3A and 3B, the developer escape hole 17 is located at the narrowest point U between the supply amount limiting member 16 and the lower developing roller l2. It was established on 16th. Reference numeral 18 denotes a guide member provided on the surface of the supply amount limiting member l6 on the paddle 15 side along the developer escape hole l7 and inclined diagonally upward. Further, in this case, it is preferable that the six fixed magnets N and S in the lower developing roller l2 be provided as follows. That is, as shown in FIG. 3(A), the developer escape hole 1
A point M on the lower developing roller 12 side corresponding to 7 is connected to two fixed magnets N, which are provided close to the supply amount limiting member 16
Set it to the middle position of S. That is, the fixed magnet S is arranged 30 degrees above the line connecting the center 0 of the lower developing roller l2 and the point M, and the fixed magnet N is arranged 30 degrees below. , N as a reference, and the other four fixed magnets S, N are arranged.

Reference numeral 19 denotes a stirring member which is provided on the downstream side of the inclined return plate l4 in the return direction and rotates in the direction of arrow F, and is used to move the toner supply member 2N from the toner supply hopper 20 (see FIG. 2) connected to the developing case 10 (see FIG. 2). The toner supplied through the agitating member 19 and the developer from the inclined return roller 14 are agitated, and the developer that has passed through the agitating member 19 is sent toward the paddle 15. Note that the conveyance roller 13, paddle 15. It is assumed that the stirring member 19 is stopped during non-developing operation.

Next, the operation of the above-mentioned developing device 3 will be explained. During copying, when a copy key (not shown) is turned on, the developing device 3 enters a developing operation, and the photoconductor 1 and both developing rollers 11 . 12, conveyance roller 13, paddle 15.
The stirring members 19 begin to rotate in respective predetermined directions. In the initial stage of the developing operation, the developer G sent out by the paddles 1 and 5 rotating in the direction of the arrow E is shown in FIG.
As shown in A), the developer passes through the developer passage gap K below the supply amount limiting member 16 and is supplied to the lower developing roller l2 side. At this time, even if a large amount of developer G flows between the lower developing roller 12 and the supply amount limiting member l6 due to the rotation of the lower developing roller 12 in the direction of arrow C, the lower developing roller 12 and the supply amount limiting member l6 Part U where the gap is the narrowest
Moreover, since the developer escape hole l7 is opened in the supply amount limiting member 16 in this portion U,
As shown in FIG. 2B, the excess developer G that cannot pass through the portion U passes through the developer escape hole 17 and is pushed out toward the paddle 15 side of the supply amount limiting member 16.
The excess developer G that has passed through the developer escape hole 17 in this way flows toward the paddle l5.
Stir again by 5.

As in the above-described embodiment, the point M of the lower developing roller l2 example corresponding to the developer escape hole 17 is located at an intermediate position between the two fixed magnets N and S provided close to the supply amount limiting member l6. When these fixed magnets N
, S is least influenced by the magnetic force of the developer G, so that escape of the developer G from the developer escape hole 17 is facilitated.

Note that when the developing device 3 is in a steady state, the upper developing roller 11 and the lower developing roller l2 rotate in a predetermined manner, and even if they flow between the lower developing roller l2 and the supply amount limiting member l6, they do not rotate in their respective predetermined rotational directions. The electrostatic latent image formed on the surface of the photoreceptor 1 is developed by passing between the upper developing roller l1 and the lower developing roller l2 and being supplied to the surface of the photoreceptor 1 by the rotation of both developing rollers 11 and 12. There is no problem as it will be served to The present invention is not limited to the above-described embodiment, and the position of the developer escape hole 17 formed in the supply amount limiting member 16 is the narrowest part between the lower developing roller l2 and the supply amount limiting member 16. It may be in the vicinity of .

〔Effect of the invention〕

As explained above, in the present invention, since the developer escape hole is provided in the supply amount limiting member at or near the position where the gap between the supply amount limiting member and the lower developing roller is the narrowest, it is possible to Even if a large amount of developer is supplied between the supply amount limiting member and the lower developing roller through the developer passing gap formed below the supply amount limiting member at the initial stage of operation, the excess developer will not reach the supply amount limiting member. Since the developer is pushed out in a direction away from the photoreceptor through the developer escape hole, there is no chance of developer clogging near the photoreceptor. Therefore, unlike conventional developing devices of this type, there is no sudden load fluctuation caused by a large amount of developer being supplied to the photoreceptor side when the developing device is started, and the prescribed development and eventually copying can be carried out smoothly. It will be done.

Further, scattering of the developer can also be prevented.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, FIG. 1 is a sectional view showing an example of a developing device according to the present invention, and FIG. 2 is a sectional view of an electrostatographic copying machine incorporating the developing device. 3A and 3B are enlarged views of the main parts for explaining the operation. FIGS. 4(A) and 4(B) are sectional views showing essential parts of a conventional developing device for explaining the prior art and its drawbacks. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 3...Developing device, 10...Developing case, 1l...Upper developing roller, 12...Lower developing roller, 15...Baddle (developer supply means>), 16・
...Supply amount limiting member, l7...Developer escape hole. Applicant Sanda Kogyo Co., Ltd. Agent Patent attorney Hideo Fujimoto Figure 3 (A) CB) Figure 4 (A) (B) = η

Claims (1)

[Claims] An upper developing roller that rotates in the opposite direction so that the direction of movement is opposite to the surface of the photoreceptor, and a lower developing roller that rotates in the same direction as the surface of the photoreceptor are placed in close proximity to each other in the developing case. At the same time, a developer supplying means for supplying developer to the lower developing roller side is provided in the lower part of the inside of the developing case, and a supply amount limiting member for restricting the amount of developer supplied to the lower developing roller side. In the developing device in which the supply amount limiting member is provided between the lower developing roller and the developer supplying means, the developer is placed at or near a position of the supply amount limiting member where the distance between the supply amount limiting member and the lower developing roller is the narrowest. A developing device characterized by having an escape hole.