JPH0470778A - Developing device - Google Patents

Abstract

PURPOSE:To obtain the stabilization of toner density control and to shorten the electrifying time of replenished toner ad a developer by providing a magnet for napping the developer inside a housing in a vertical direction in the vicinity of the toner replenishing port of the external wall of the housing. CONSTITUTION:A stick magnet 7 is fixed on a place corresponding to the toner replenishing port 5 among the outside surfaces of the side walls of the housing 2. The developer 9 under the toner replenishing port 5 is napped in the vertical direction by the magnetic force line of the stick magnet 7, and the developer 9 at that place has a through gap from the almost top to the bottom in the vertical direction. Therefore, when the toner 10 is replenished from the toner replenishing port 5 on the top of the gap, the toner 10 is supplied on the whole of the layer of the developer 9 from the top layer to the bottom layer of the developer 9. When the developer 9 is carried to the downstream side, a little, by the rotation of a stirring paddle 4, the replenished toner 10 is already dispersed on the whole of the developer 9. Thus, the stabilization of the toner density control is obtained, and the replenished toner and developer can be electrified in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a developing device, and more specifically, to a developing device incorporated into an image forming apparatus such as a copying machine or a facnomy machine using a two-component developing method. .

(0) Prior Art Conventionally, as a developing device incorporated in an image forming apparatus using a two-component developing method, a developing housing is disposed adjacent to a photosensitive drum, and the developing device is placed close to and facing the photosensitive drum within the housing. The sleeve is rotatably supported, and a stirring paddle that stirs the developer in the housing and sends it to the developing sleeve is rotatably supported in the housing, and the developer is moved into the housing to the extent that the stirring paddle is hidden. There are some known that contain chemicals.

Such developing devices are usually equipped with a toner concentration detection means such as a magnetic permeability sensor, and when the toner concentration in the developer decreases, the stirring paddle (almost hidden by the developer) Drop the replenishment toner onto it. Then, this supplied toner is mixed with the developer (toner and carrier) near the stirring paddle and supplied to the developing sleeve.

(c) Problems to be Solved by the Invention In the developing device as described above, the specific gravity of the developer near the stirring paddle in the developing housing and the specific gravity of the replenishment toner that has fallen onto the stirring paddle are important. It is about 51, which is a big difference. For this reason, the replenishment toner that falls onto the stirring paddle does not sink into the developer very much, but remains in the shape of a mountain on top of the developer, and is drawn into the developer from the foot of the mountain. In this way, it is stirred little by little.

Therefore, the toner concentration detection means detects toner shortage,
Even though toner is being replenished, the response until a predetermined toner concentration is reached is slow. When the "toner supply stop" signal is sent, more toner than necessary has already been supplied into the developing housing (it has not yet been mixed with the developer).

For this reason, the toner concentration may exceed the set value after a while after the toner is replenished, and there is a risk that toner scattering may occur. Another problem was that the developer and toner could not be charged in a short time.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a developing device that has good stability in toner density control and is capable of charging replenishing toner and developer in a short time. .

(d) Means for Solving the Problems and Their Effects This invention includes a developing housing provided adjacent to an image carrier, and a developing developer rotatably supported within the housing in close proximity to and facing the image carrier. a developer carrier, a stirring member that is rotatably supported within the housing and stirs the developer in the housing and sends it to the developer carrier; and a stirring member that is provided at the top of the housing and supplies toner into the housing. In addition, there is a toner supply port on the outer wall of the housing near the toner supply port.
This developing device is equipped with a magnet that causes the developer in the housing to stand up in the vertical direction, thereby creating a vertical gap in the developer.

That is, the developing device of the present invention is characterized in that a magnet is provided near the toner supply port on the outer wall of the housing to cause the developer in the housing to stand up in spikes in the vertical direction. and,
Such a magnet creates a vertical gap in the developer to ensure that the supplied toner penetrates into the developer.

Here, the magnet used is, for example, a bar magnet.

Further, the stirring member is preferably made of a non-magnetic material such as plastic or aluminum alloy.

(E) Example Hereinafter, the present invention will be described in detail based on one example shown in the drawings. Note that this invention is not limited to this.

In FIGS. 1 to 3, a developing device l of a copying machine includes a developing housing 2 provided adjacent to a photosensitive drum (not shown) as an image carrier, and a developing housing 2 located close to the photosensitive drum within this housing 2. It has a developing sleeve 3 as a developer carrier that is rotatably supported to face each other. housing 2
A partition wall 8 is provided inside along the axial direction of the developing sleeve 3. The interior of the housing 2 is divided by the partition wall 8 into a first developer storage chamber II and a second developer storage chamber 12.

Each of the first developer storage chamber 11 and the second developer storage chamber 12 is rotatably supported by the housing 2 and stirs the developer (toner and carrier) 9 in the housing 2 to form a developing sleeve 3. A plastic stirring paddle 4 is provided as a stirring member for feeding the water to the water. Further, a toner replenishment port 5 for replenishing toner IO into the housing 2 is formed on the upper surface of the housing 2 on the side of the first developer storage chamber ll.

Therefore, the toner 10 replenished from the toner supply port 5
The developer moves in the direction of the arrow while being stirred with the developer 9 in the first developer storage chamber 11, and is sent to the second developer storage chamber 12. The developer 9 sent to the second developer storage chamber 12 moves in the direction of arrow B while being further stirred and is supplied to the developing sleeve 3.

In addition, the bottom part j of the housing 2 on the first developer storage chamber 11 side
A magnetic permeability sensor 6 is provided downstream of the toner replenishment port 5. Further, a bar magnet 7 is fixed to a portion of the outer surface of the side wall of the housing 2 corresponding to the toner replenishing port 5, for example, with the S pole facing upward and the N pole facing downward.

In this developing device 1, the developer 9 below the toner replenishing port 5 stands up in spikes in the vertical direction due to the lines of magnetic force of the bar magnet 7. Then, in the developer 9 at that location, a vertical gap is created that penetrates almost from the top to the bottom. If you look at this situation from a plane, it looks like a cedar forest seen from above (
(See Figure 3).

When the toner IO is supplied from the toner supply port 5 above these gaps, the toner IO is supplied to the entire developer 9 layer from the upper layer to the lower layer.

By the time the developer 9 is conveyed a little downstream by the rotation of the stirring paddle 4, the replenishment toner 10 has already been dispersed throughout the developer 9.

Thus, according to this developing device AT, the response to the magnetic permeability sensor 6 is quick and the accuracy of toner concentration control is improved. Furthermore, charging of the replenishment toner 10 and the developer 9 is also performed quickly.

(f) Effects of the Invention Since the developing device of the present invention is configured as described above, the stability of toner concentration control is good and replenishment toner and developer can be charged in a short time.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the invention. That is, FIG. 1 is an explanatory diagram of the configuration of the developing device seen from the front, FIG. 2 is an explanatory diagram of the configuration of the developing device seen from the side, and FIG.
The figure is a partially omitted plan view of the developing device. ■...Developing device, 2...Developing housing, 3...Developing sleeve (developer carrier), 4...
... Stirring paddle (stirring member), 5...
Toner supply port, 6... - Magnetic permeability sensor, 7... Bar magnet (magnet), 8... Partition wall, 9... Developer, 10... ...Toner number is number 2! l! !

Claims (1)

[Claims] 1. A developing housing provided adjacent to the image carrier;
A developer carrier rotatably supported within the housing in close opposition to the image carrier, and a developer carrier rotatably supported within the housing to agitate the developer in the housing and send it to the developer carrier. The device includes a stirring member and a toner replenishment port provided at the top of the housing for replenishing toner into the housing, and further includes a toner replenishment port on the outer wall of the housing that causes the developer in the housing to stand up in a vertical direction. , a developing device comprising a magnet thereby creating a vertical gap in the developer. 2. The developing device according to claim 1, wherein the stirring member is made of a non-magnetic material.