JPH0631481Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a developing device, and more particularly, to a developing device that effectively prevents toner cloud generated in the developing housing from flowing out of the housing. Regarding improvement.

[Prior Art] Conventionally, as a developing device used in an image forming apparatus such as a copying machine, as shown in FIG. 3, for example, a developer G is stored in the vicinity of a latent image carrier 1 such as a photosensitive drum. A housing 2 is provided, and an opening 3 is formed on the side of the latent image carrier 1 of the housing 2, while a magnet roll 4 is arranged near the opening 3 of the housing 2 and a housing adjacent to the magnet roll 4 is provided. The blender 5 and the paddle wheel 6 are arranged in the interior of the blender 2 from the back side, and the blender 5
The developer G charged in the housing 2 is triboelectrically charged, the developer G frictionally charged by the paddle wheel 6 is conveyed to the magnet roll 4 side, and the latent image carrier 1 is passed through the magnet roll 4 via the magnet roll 4. To supply the developer G to develop the latent image on the latent image carrier 1 with toner. In FIG. 3, reference numeral 7 is a trimming plate which is provided above the magnet roll 4 and regulates the thickness of the developer G on the magnet roll 4, and reference numeral 8 is a surplus generated near the trimming plate 7. This is a mixer plate that returns the developer G of to the blender 5 side.

[Problems to be Solved by the Invention] By the way, in such a developing device, the internal pressure in the housing 2 rises due to the rotational movement of the blender 5, the paddle wheel 6, etc. The toner cloud soars, and the soaring toner cloud flows out of the housing 2 through the gap between the housing 2 and the magnet roll 4, mainly the gap between the housing 2 on the side where the trimming plate 7 is not disposed and the magnet roll 4. However, there arises a problem that the parts around the developing device are contaminated with the toner cloud.

In order to eliminate such a situation, in the conventional case, the third
As shown in the figure, an air suction duct 11 is provided outside the housing 2, and a blower is provided on the end side of the air suction duct 11.
In addition to disposing 12 and a filter 13 for adsorbing the toner cloud in the air suction duct 11, the toner cloud from the inside of the housing 2 is forcibly sucked and removed, and FIG. As shown, a magnet seal 15 is provided on the opening edge 3a of the housing 2, and the space between the magnet seal 15 and the latent image carrier 1 is sealed with the developer G to prevent the toner cloud from flowing out of the housing 2. Something is provided to prevent it.

However, in the case of the former type in such conventional toner cloud preventing means, since the air suction duct 11 is provided outside the housing 2, not only the developing device becomes large, but also as a constituent member. Since the air suction duct 11, the blower 12 and the filter 13 are used, the number of parts is increased, which causes a problem that the device cost is increased. Also, in the latter type,
Although the problem of increasing the size of the developing device does not occur, toner accumulates on the magnet seal 15 with the passage of time, and on the contrary, the toner adheres to the latent image carrier 1 side, which causes a problem of degrading image quality. Occurs. Further, since the magnet seal 15 is separately provided on the opening edge portion 3a of the housing 2, the problem that the cost of the developing device increases correspondingly cannot be avoided.

[Means for Solving Problems] The present invention has been made in view of the above problems, and makes it possible to make the apparatus compact and inexpensive without impairing the returning operation of the developer. Provided is a developing device capable of preventing the toner cloud from flowing out of the housing.

That is, the present invention has a housing for accommodating the developer in the vicinity of the latent image carrier, opens an opening on the latent image carrier side of the housing, and conveys the toner inside the rotary sleeve near the opening of the housing. A magnet roll having fixed magnetic poles is provided, and a trimming member for regulating the thickness of the developer supplied to the magnet roll is provided in the housing portion located on the developer supply portion side of the magnet roll. Assuming a developing device in which a developer whose thickness is regulated is introduced onto a latent image carrier via a magnet roll to develop the latent image on the latent image carrier by toner, the developer returning portion side of the magnet roll. Of the housing located at the position away from the housing opening, projecting toward the magnet roll side, and having a planar shape along the circumferential direction of the magnet roll. An extending spacer portion is provided, and a minute gap having a substantially uniform width dimension which is 1 to 2 times the thickness of the developer regulating layer by the trimming member is formed between the spacer portion and the magnet roll, and the spacer portion is provided. In the opposing magnet roll portions, one of the carrier magnetic poles on which the vertical magnetic field acts is arranged near the center of the spacer portion.

In this type, the developer transport direction of the magnet roll is not limited to the same direction as the latent image carrier, but may be the opposite direction to the latent image carrier. Further, the arrangement position and structure of the trimming member, the trimming gap, and the like may be appropriately changed in design depending on the type of developer and the development method. Further, as the member stored in the housing, in addition to the magnet roll, a stirring member for stirring the developer charged in the housing, a conveying member for guiding the stirred developer to the magnet roll side, or the like is appropriately used. A functional member is used.

Further, the spacer portion provided in the housing may be formed integrally with the housing, or may be a separate member. In addition, when designing the housing, it is necessary to prevent the developer from directly overflowing from the housing opening when the developer that has passed through the developing portion remains attached to the magnet roll and returns to the inside of the housing. It is necessary, and the gap resistance near the housing opening must be made relatively small. From this point, it is necessary to select a portion appropriately separated from the housing opening as the formation portion of the spacer portion. Further, the minute gap between the spacer portion and the magnet roll can effectively prevent the outflow of the toner cloud generated in the housing without extremely increasing the passage resistance of the developer returning to the inside of the housing. It is necessary to select in the range, and the preferable size is about 1 to 2 times, and more preferably about 1.2 to 1.7 times based on the trimming gap of the developer on the magnet roll.

[Operation] According to the technical means as described above, a desired minute gap is formed between the magnet roll and the spacer portion of the housing, so that the developer returning to the inside of the housing while being attached to the magnet roll is the spacer portion. When you reach the vicinity,
This developer rises based on the magnetic field of the magnet roll and substantially closes the minute gap. For this reason,
The toner cloud generated in the housing is effectively blocked by the minute gap portion.

In particular, in the present invention, the spacer portion extends in a planar shape along the circumferential direction of the magnet roll, and the magnetic roll portion facing the spacer portion acts on the vertical magnetic field component near substantially the center of the spacer portion. Since one of the transport magnetic poles is arranged, the developer near the spacer portion behaves as follows.

That is, the spikes of the developer on the magnet roll are still in a sleeping state at the time of reaching the inlet portion of the spacer portion, and completely rise along the vertical magnetic field component at the time of reaching the approximate center of the spacer portion. Further, since the developer gradually sleeps on the outlet portion side of the spacer portion, the developer is smoothly guided into the spacer portion, and when the developer reaches substantially the center of the spacer portion, the developer is substantially closed between the wall surface of the spacer portion, Further, it smoothly passes through the spacer portion and returns to the inside of the housing.

[Embodiment] Hereinafter, the present invention will be described in detail based on an embodiment shown in the accompanying drawings.

In FIG. 1, a developing device using a two-component developer G is shown, and the basic configuration is such that the developer G is stored in the vicinity of the latent image carrier 1 such as a photosensitive drum. A housing 2 is provided, and an opening 3 is formed on the side of the latent image carrier 1 of the housing 2, while a magnet roll 4 is arranged near the opening 3 of the housing 2 and a housing adjacent to the magnet roll 4 is provided. A blender 5 and a paddle wheel 6 are arranged in the inside from 2 and a housing portion located on the developer supply portion side of the magnet roll 4 (upper side of the magnet roll 4 in this embodiment).
2a is provided with a trimming plate 7 for regulating the thickness of the developer G on the magnet roll 4, and a mixer plate 8 similar to the conventional one is provided in the vicinity of the trimming plate 7.

In this embodiment, the developer return portion side of the magnet roll 4 (the lower side of the magnet roll 4 in this embodiment).
The housing portion 2b located at is provided with a spacer portion 20 protruding toward the magnet roll 4 side. The spacer portion 20 is provided at a position appropriately separated from the position of the opening 3 of the housing 2, and is formed by bulging a corresponding portion of the housing portion 2b toward the magnet roll 4 side in a convex shape. Further, the dimension m of the minute gap 21 between the spacer portion 20 and the magnet roll 4 is approximately in the range of t ≦ m ≦ 2t, where t is the trimming gap between the trimming plate 7 and the magnet roll 4. Is set.

In addition, in this embodiment, the magnet roll 4 is used.
As a plurality of sets of carrier magnetic poles 4b for carrying the developer are embedded and fixed on the peripheral surface of the fixed shaft 4a, and a repelling magnetic pole 4c for peeling the developer.
One set (N pole in this embodiment) is embedded and fixed, and a sleeve 4d is rotatably mounted around the fixed shaft 4b. A magnet roll facing the substantially center of the spacer portion 20 is used. The S pole of the carrier magnetic pole 4b is arranged on the fixed shaft 4a portion of No. 4.

Therefore, according to the developing device of this embodiment, the developer G charged in the housing 2 is frictionally charged by the blender 5 and then supplied to the magnet roll 4 side by the paddle wheel 6. Then, the developer G supplied onto the magnet roll 4 is regulated by the trimming plate 7 to the supply amount of the trimming gap t, and also sequentially moves on the sleeve 4d along the carrying magnetic pole 4b to form a latent image. The latent image on the carrier 1 is developed with toner.
After that, the developer G remaining on the magnet roll 4 is
Moving on the sleeve 4d along the carrier magnetic pole 4b,
It returns to the inside of the housing 2 on the developer return side of the magnet roll 4.

At this time, as shown in FIG. 1, since the gap 22 between the housing portion 2b and the magnet roll 4 in the vicinity of the opening 3 of the housing 2 is ensured to be relatively wide, the developer returning to the housing 2 can be prevented. The situation where G ′ overflows in the vicinity of the opening 3 of the housing 2 is effectively avoided.
In addition, the returning developer G ′ is transferred to the sleeve 4d along the transport magnetic pole 4b.
As it moves upward, it passes through the minute gap 21 between the spacer portion 20 and the magnet roll 4, but at this time, the return developer G'is very small as shown in FIG. In the gap 21 portion, the minute gap 21 is substantially closed by rising appropriately along the magnetic field perpendicular to the magnetic field in the direction of arrow A.
Therefore, even if the internal pressure of the housing 2 rises due to the rotational movement of the blender 5 and the paddle wheel 6 and a toner cloud is generated in the housing 2, the toner cloud passes through the minute gap 21 and the outside of the housing 2 Is almost never leaked to. In particular, the dimension m of the minute gap 21
It has been experimentally confirmed that the toner cloud is more reliably prevented from flowing out when is set in the range of 1.2t ≦ m ≦ 1.7t. The trimming plate 7 effectively prevents the toner cloud from flowing out of the housing 2 from the upper side of the housing 2.

Further, in this embodiment, since the carrier magnetic pole 4b for exerting a vertical magnetic field is provided near the center of the spacer portion 20 at the portion of the magnet roll 4 facing the spacer portion 20, the magnet roll 4 is provided. Top return developer G '
The ears of the stalks will rise completely along the vertical magnetic field of the carrier pole 4b when reaching the approximate center of the spacer portion 20, but are still in a sleeping state at the entrance portion and the exit portion of the spacer portion 20. Therefore, the returning developer G ′ is used for the spacer portion 20.
It is smoothly guided inside, passes smoothly through the spacer portion 20, and returns to the inside of the housing 2.

Further, since the repelling magnetic pole 4c, which is the developer peeling portion of the magnet roll 4, is provided on the inner side of the minute gap 21, the return developer G ′ peeled from the magnet roll 4 is deposited on the minute gap 21. Then, there is no possibility that the returning operation of the returning developer G ′ into the housing 2 is impaired.

[Advantage of the Invention] According to the developing device of the present invention, a spacer portion extending in a planar shape along the circumferential direction of the magnet roll is provided at an appropriate position on the developer return side of the housing facing the magnet roll. A minute gap having a substantially uniform width dimension which is 1 to 2 times the developer regulation layer thickness by the trimming member is formed between the spacer portion and the magnet roll, and the spacer portion is provided at the magnet roll portion facing the spacer portion. Since one of the carrier magnetic poles on which the vertical magnetic field acts is arranged in the vicinity of the approximate center, the following basic effects are obtained.

The size of the minute gap between the planar spacer portion and the magnet roll is optimized in relation to the thickness of the developer regulating layer by the trimming member, and the planar spacer is generated by the rising of the return developer due to the vertical magnetic field of the carrier pole. Since the return developer is made to come into close contact with the wall surface near the center of the part with a certain width, it is possible to seal the minute gap portion with the return developer in an airtight manner. It is possible to reliably prevent the generated toner cloud from flowing out of the housing.

The vertical magnetic field of the carrier pole is applied to the vicinity of the center of the planar spacer to keep the spikes of the developer on the magnet roll at the time of reaching the entrance of the spacer and at the exit side. As a result, it is possible to smoothly guide the returning developer into the minute gap and to smoothly pass the returning developer inside the minute gap without accumulating the returning developer. Can be stabilized.

As a conventional method for preventing toner cloud outflow,
It is possible to prevent the toner cloud generated in the housing from flowing out of the housing with a simple structure in which a spacer is simply provided in a part of the housing without using a member such as a member for forced suction or a magnet seal. .

[Brief description of drawings]

FIG. 1 is a sectional explanatory view showing an embodiment of a developing device according to the present invention, FIG. 2 is a detailed view of a II portion in FIG. 1, FIG. 3 and FIG.
The drawings are cross-sectional explanatory views showing different examples of conventional developing devices. [Explanation of symbols] (1) …… Latent image carrier (2) …… Housing (3) …… Opening (4) …… Trimming plate (trimming member) (20) …… Spacer (21) …… Small Gap

Continuation of front page (56) Reference JP-A-60-159770 (JP, A) JP-A-61-110177 (JP, A) JP-A-61-175662 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A housing for accommodating a developer is provided in the vicinity of a latent image carrier, an opening is formed on the side of the latent image carrier of the housing, and a carrier magnetic pole is provided inside the rotary sleeve near the opening of the housing. Is provided with a magnet roll, and a trimming member for regulating the thickness of the developer supplied to the magnet roll is provided in the housing portion located on the developer supply portion side of the magnet roll. In a developing device that guides a regulated developer onto a latent image carrier through a magnet roll and develops the latent image on the latent image carrier by toner, the developer is located on the developer return side of the magnet roll. A space that protrudes toward the magnet roll and extends in a planar shape along the circumferential direction of the magnet roll at a portion of the housing that is separated from the housing opening. Is provided, and a minute gap having a substantially uniform width dimension of 1 to 2 times the developer regulation layer thickness by the trimming member is formed between the spacer portion and the magnet roll, and faces the spacer portion. The developing device is characterized in that one of the carrier magnetic poles on which the vertical magnetic field acts is arranged near the center of the spacer portion in the magnet roll portion.