JPH03170977A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of concentration of a toner and to stabilize the toner concentration by constituting the device so that a part of the toner replenished to a first stirring line from a toner replenishing port is bypassed to the downstream side of a second stirring line from a notch part. CONSTITUTION:A part of a toner passes through a notch part 3a of a partition plate 3 from a first stirring line A and flows out to a second stirring line B and brought to reflux to a first stirring line A from the downstream end of a second stirring line B, and the other toner circulates through a circulating line consisting of a first stirring line A and a second stirring line B. A part of the toner carried through the circulating line is developed and consumed to a photosensitive drum from a developing roller while it is moving through a second stirring line B, and the residual toner is joined with the toner which flows out through the notch part 3a of the partition plate 3 and brought to reflux to a first stirring line A from the downstream end of a second stirring line B. Subsequently, toner concentration after the confluence is detected by a toner concentration detecting means 7, and by a result of detection, the toner concentration is controlled. In such a way, the toner concentration supplied to the photosensitive drum 8 can be supplied uniformly and stably.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a developing device installed in an image forming apparatus such as a copying machine, and particularly to a developing device that uniformly and stably supplies toner density to a photoreceptor drum. This invention relates to the structure of a developing device.

[Conventional technology]

FIG. 3 shows a partially cutaway perspective view of an embodiment of a conventional developing device having a first stirring path and a second stirring path separated by a partition plate inside the developing container. The developing device shown in the figure is
The inside of the developer container l is partitioned by a partition plate 3, forming a first stirring path A and a second stirring path B, and further a second stirring path B.
A developing roller 6 is disposed adjacent to. In this developing device, toner supplied from a toner replenishment port 2 provided at an appropriate position above a developing container 1 on the upstream side of a first stirring path A is stirred and charged by a stirring spiral 4 in the first stirring path A. It is conveyed to the downstream side while being stirred, and is conveyed to the second stirring path B from the hole 1a at the downstream end. Further, the conveyed toner is conveyed from the upstream side to the downstream side in the second stirring path B while being stirred and charged by the stirring spiral 5 in the second stirring path B, and is sucked by the developing roller 6 during this conveyance. Furthermore, the toner attracted by the developing roller 6 is developed and consumed by the photosensitive drum 8. Then, the remaining toner is transferred to the second stirring path B.
The toner is returned to the first stirring path A from the hole 1b at the downstream end of the toner, and is circulated through the first and second stirring paths A and B together with newly replenished toner. Further, the toner density after development is detected by a sensor 7.

[Problem to be solved by the invention]

By the way, in the conventional developing device described above, the stirring path is made as long as possible in order to sufficiently charge the replenished toner while stirring, but the replenished toner passes through the second stirring path B. The toner is consumed by the developing operation while being conveyed, and the toner concentration becomes low on the downstream side Cg5 in the second stirring path B, making it difficult to obtain a uniform toner concentration over the entire developing roller 6. Further, the toner concentration after replenishment is detected by the sensor 7 after the toner moves through the first stirring path A and the second stirring path B, and the toner concentration is controlled based on this detection result. A time delay occurs in density control, making it difficult to control stable toner density.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device that uniformly and stably supplies toner density to a photoreceptor drum.

[Means to solve the problem]

The present invention provides a circulating stirring path consisting of a first stirring path and a second stirring path formed by partitioning the inside of the developing device with a partition plate in order to stir and charge toner, and an upstream side of the first stirring path. It has a toner replenishment port provided on the side, and a toner concentration detection means provided downstream of the second stirring path adjacent to the developing roller, and based on the detected toner concentration. In the developing device in which the amount of toner replenishment is controlled, one or more notches are provided on the replenishment port side of the partition plate.

[Effect]

According to the present invention, a part of the toner flows from the i-th stirring path to the second stirring path through the notch of the partition plate, and flows back from the downstream end of the second stirring path to the first stirring path. do. Further, other toners circulate through a circulation path consisting of a first stirring path and a second stirring path. A part of the toner being conveyed through the circulation path is developed and consumed from the developing roller onto the photoreceptor drum while moving through the second agitation path, and the remaining toner flows out through the perforated portion of the partition plate. The second toner merges with the second toner.
from the downstream end of the stirring path to the first stirring path. Then, the toner concentration after this merging is detected by a toner concentration detection means, and the detected result. The toner concentration is controlled by the effect.

〔Example〕

An embodiment of the present invention will be described based on the drawings.

FIG. 1 is a partially cutaway perspective view of a developing container of a developing device according to the present invention. Moreover, FIG. 2 shows a plan sectional view of the developer container. A developing container 1 of this developing device is partitioned into two chambers by a partition plate 3, and a first stirring path A and a second stirring path B for stirring and charging the toner are formed. Further, a toner replenishment port 2 is formed at a suitable location on the upper surface of the developer container assembly, upstream of the first stirring path A. A toner hopper (not shown) is provided in the upper part of the developer container 1, and toner is supplied from the toner hopper through the replenishment port 2.

Stirring spirals 4 and 5 are provided in the first and second stirring paths A and B, respectively. Stirring spiral 4.5
are rotated by drive mechanisms (not shown), the stirring spiral 4 transports toner in the direction of arrow a, and the stirring spiral 5 transports toner in the direction of arrow b. Passages 1a and 1b are provided between both ends of the partition plate 3 and the side plate of the developer container 1, and the passage 1a serves as a passage for guiding the toner from the first stirring passage A to the second stirring passage B, and the passage 1b
is a passageway for guiding the toner from the second stirring passage B to the first stirring passage A. A toner circulation path (hereinafter referred to as a first circulation path) is formed by these paths la, lb, the first stirring path A, and the second stirring path B, and the toner passes through the first circulation path as a carrier. The material is conveyed while being stirred with the material, and is effectively charged. Further, a notch 3a is provided at a proper position on the toner supply port 2 side of the partition plate 3, and the notch 3a and the first stirring path A1, the second stirring path B, and the passage 1b are connected to the first stirring path A1, the second stirring path B, and the passage 1b. A bypass of one circulation path (hereinafter referred to as a second circulation path) is formed. The cutout portion 3a is preferably one in which a plurality of cutouts having a predetermined width are provided at a predetermined interval, and the cutout portion 3a is shown in which two cutouts are formed in the figure. Said second
A part of the toner conveyed through the first stirring path B by the circulation path moves to the second stirring path B through the notch 3a, and then passes through the first stirring path B.
It joins with the toner that has moved through the circulation path and flows back to the first stirring path A from the path 1b.

In the second stirring path B, a developing roller 6 is arranged in parallel with the stirring spiral 5. A predetermined voltage is applied to the developing roller 6 by a power source (not shown), and a portion of the toner moving in the second stirring path B is attracted to the surface of the developing roller 6. There is. During development, the developing roller 6 is rotationally driven by a drive mechanism (not shown), and the toner attracted to the roller surface is attracted to the photoreceptor drum 8 and consumed to develop the electrostatic latent image.

A sensor 7 for detecting toner concentration is disposed at an appropriate position on the side plate of the developer container 1 on the downstream end side of the second stirring path B. The sensor 7 detects the concentration of the toner circulating in the first circulation path and the second circulation path, and based on the detection result, a predetermined amount of toner is controlled by a control means (not shown) to maintain the toner concentration constant. are being replenished.

In the above structure, most of the toner replenished from the replenishment port 2 is conveyed from the first stirring path A to the second stirring path B via the passage 1a. The toner conveyed through the second stirring path B is consumed by the developing operation, and the toner concentration on the downstream side of the second stirring path B is lower than that on the upstream side. On the other hand, supply port 2
A part of the toner supplied from the toner flows out from the notch 3a provided in the partition plate 3 to the downstream side C of the second stirring path B, and
It merges with the toner conveyed through the first circulation path to prevent a decrease in the toner concentration in the downstream side C portion of the second stirring path B. This reduces the imbalance of toner concentration in the second stirring path B, and stabilizes the toner concentration. Also,
A portion of the toner replenished from the replenishment port 2 quickly flows out from the notch 3a to the second stirring path B.
The toner concentration at the downstream side C section is increased. As a result, changes in toner concentration after toner replenishment are detected by the sensor 7 at an early stage, and toner replenishment is controlled, thereby stabilizing the toner concentration in the developer container 1 quickly. Especially when toner is replenished when no developing operation is being performed, the time lag between toner replenishment and detection of changes in toner concentration after replenishment is shortened, so toner concentration can be stabilized quickly. be able to. Note that the toner conveyed through the second circulation path is a part of the toner conveyed through the first circulation path, and most of the toner is conveyed through the first circulation path, so there is no influence on the toner stirring and charging operation. is small, and the developing effect does not deteriorate.

〔Effect of the invention〕

As explained above, according to the present invention, a notch is provided in the partition plate that partitions the first stirring path and the second stirring path,
Since a part of the toner supplied to the first stirring path from the toner supply port is bypassed from the notch to the downstream side of the second stirring path, the toner is consumed by the developing operation and is not used for the second stirring path. A decrease in toner concentration occurring on the downstream side of the path is prevented, and the toner concentration within the developing device can be stabilized. Further, since changes in the toner concentration after replenishment can be detected early, the toner concentration can be quickly stabilized. By stabilizing these toner concentrations, a good developing effect can be obtained, which in turn enables suitable image formation.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a developing container of a developing device according to the present invention, FIG. 2 is a plan sectional view showing the developing container of a developing device according to the present invention, and FIG. 3 is a developing device of a conventional developing device. FIG. 3 is a partially cutaway perspective view of the container. DESCRIPTION OF SYMBOLS 1... Developer container, la, lb... Passage, 2... Replenishment port, 3... Partition plate, 3a... Notch, 4, 5...
- Stirring spiral, 6... Developing roller, 7... Sensor, 8... Photosensitive drum, A... First stirring path, B
...Second stirring path.

Claims (1)

[Claims] 1. A circulating stirring path consisting of a first stirring path and a second stirring path formed by partitioning the inside of the developing container with a partition plate in order to stir and charge the toner, and a circulating stirring path on the upstream side of the first stirring path. A toner replenishment port is provided, and a toner concentration detection means is provided downstream of a second stirring path provided adjacent to the developing roller, and the toner replenishment is performed based on the detected toner concentration. A developing device in which an amount is controlled, characterized in that one or more notches are provided on the side of the replenishment port of the partition plate.