JPH04190379A - Developing device - Google Patents

Abstract

PURPOSE:To prevent stagnation of toner in the vicinity of a toner replenishing port so as to fully agitate and convey of the toner by reversing the rotation of a screw for conveying the toner to a position near the toner replenishing port. CONSTITUTION:A conveyer screw 2 is reversely rotated so fully convey toner to a position in the vicinity of a toner replenishing port 1 so that development (normal rotation) and the replenishment of the toner are simultaneously carried out. Subsequent to the second cycle, the operation is carried out similarly. By reversing the rotation of the screw just before the second cycle, a part of the toner which remains, without being conveyed, in the vicinity of the replenishing toner upon first cycle toner replenishment is mixed with a developer by agitation, and is conveyed while it is agitated. Further, stagnation of the toner which occurs the second cycle toner replenishment is agitated and conveyed upon reverse rotation during the third cycle. Thus, by driving the conveyer screw 2 in the reverse direction for a predetermined time just before development, the toner fed to the toner replenishing port 1 is fully mixed with the developer by agitation during development, and is then fed to a developer circulating passage.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a toner to be transported from a toner replenishment port into a developer circulation path by a toner transport screw.
The present invention relates to a developing device such as a digital copying machine using component developers.

[Prior Art] A developing device such as a digital copying machine using a two-component developer is generally constructed as shown in FIG. 5.6. In other words, a pair of screws 2 for stirring and transporting toner and developer.
．． 3, a developing sleeve 4, a partition plate 5, etc. The toner conveying screw 2 extends outward and has a toner supply port 1 formed at its end. Therefore, the developer is always in the circulation path shown by the arrow in FIG. 6, and the rotation of the screws 2 and 3 keeps the developer concentration on the developing sleeve 4 shown in FIG. 5 constant. It circulates in the direction.

Also, the same amount of toner as that used for development is replenished from the replenishment port 1, and the screw 2 supplies the toner in the developer circulation path 1.
The toner is conveyed to the screw 3, merges with the developer whose concentration has been reduced by development, is stirred and conveyed, is further conveyed to the screw 3, and is developed on the developing sleeve 4. This series of operations is repeated according to the development and replenishment sequence shown in FIG.

[Problems to be Solved by the Invention] As described above, during development, the transport screw 2 rotates in the normal direction, and the developer is in the developer circulation path 10 and is not present near the toner replenishment port 1, so that toner replenishment is not possible. The toner replenished from the mouth is not conveyed properly to the developer circulation path in the developing device.
A toner buildup occurs near the replenishment port, which prevents toner from entering the replenishment port and causes it to spill out. Further, there is a problem that unevenness occurs in developer concentration, resulting in an unstable state.

Therefore, an object of the present invention is to provide a developing device that can smoothly replenish toner.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a two-component developer that is transported from a toner supply port into a developer circulation path by a toner transport screw. In a developing device such as a digital copying machine, the conveyance screw is configured to be driven in the opposite direction for a predetermined period of time immediately before the development.

Further, in the invention as set forth in claim 2, the conveyance screw is driven in the reverse direction for a predetermined period of time after the completion of development.

[Function] According to the present invention, the toner conveying screw is driven in the opposite direction for a predetermined period of time immediately before or after development, that is, in the opposite direction to the conveying direction, so that the developer is conveyed to the vicinity of the toner replenishment port. Therefore, the toner supplied to the toner supply port is well mixed with the developer during development and is conveyed to the developer circulation path.

[Embodiment] In carrying out the present invention, the intended purpose can be achieved even if the toner conveying screw is reversely rotated by a predetermined number of rotations. Therefore, although the predetermined number of rotations is included in the predetermined time, the explanation is given in terms of time in the embodiment.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1st
The figure shows the 341 embodiment, in which SR indicates the rotational direction of the toner conveying screw, and T indicates the presence or absence of toner replenishment with e and e.

When the developing device is now in the developing position shown in FIG. 5, it operates according to the sequence shown in FIG. First, conveyor screw 2
rotates in the opposite direction to sufficiently convey the developer to the vicinity of the toner supply port 1. The same operation is performed from the second time onward, in which development (forward rotation) and toner replenishment are performed simultaneously. Due to the reverse rotation of the screw just before the second development, the toner that was not transported during the first toner replenishment and remains near the replenishment port is mixed with the developer, and is transported while being stirred during the development. Further, the toner pool generated during the second toner replenishment is agitated and conveyed by the third reverse rotation.

In other words, the toner pool at the nth time of toner replenishment is n
The toner can be removed by reverse rotation of the screw just before the +1st development, and the toner can be sufficiently agitated and transported.

A second embodiment of the invention is shown in FIG. According to this embodiment, the toner conveying screw 2 is rotated in the reverse direction for a predetermined period of time after development. That is, immediately after the first development and toner replenishment, the screw 2 is rotated in the opposite direction to eliminate toner accumulation that occurs during toner replenishment, and to mix the toner with the developer. Then, during the second development, it is transported while being stirred. The toner pool generated during the second toner replenishment is agitated by reverse rotation of the screw immediately after development, and agitation is performed during the next development. In other words, n
The toner accumulated during the second toner replenishment is removed by reverse rotation of the screw immediately after the current development and is mixed with the developer, and further stirred and conveyed during the (n+1)th development.

It is clear that this embodiment can also eliminate toner accumulation.

FIG. 3 shows a third embodiment of the invention. Also in this embodiment, SR indicates the direction of rotation of the toner conveying screenie 2, and T indicates whether or not toner is replenished.

According to this embodiment, after the first development, the screw 2
The developer is conveyed to the vicinity of the toner replenishing port 1 by the reverse rotation of the toner replenishing port 1. By completing toner replenishment after the end of the reverse rotation and before the end of the copying operation, the toner and developer replenished during the second development can be conveyed while being stirred.

By continuing this operation, toner accumulation can be eliminated and toner and developer can be sufficiently stirred and transported.

[Effects of the Invention] As described above, according to the present invention, the present 11! By rotating the screw in the opposite direction to convey the developer, it is possible to eliminate toner accumulation near the toner replenishment port and to agitate and convey the developer.

[Brief explanation of the drawing]

Figures 1.2 and 3 are sequence diagrams showing different embodiments of the present invention, Figure 4 is a conventional sequence diagram, and Figure 5 is a sequence diagram showing different embodiments of the present invention.
The figure is a partially cutaway view showing one example of a developing device, and FIG. 6 is a top view thereof. 1... Toner supply port 2... Toner transport screw, developer transport screw 4... Developing sleeve 4 people Figure 1 Figure 2 Copy start
The end of copying is shown in Figure 3. The start of copying is shown in Figure 4.

Claims (1)

[Scope of Claims] 1. In a developing device such as a digital copying machine that uses a two-component developer that is transported from a toner supply port into a developer circulation path by a toner transport screw, the transport screw is A developing device characterized in that it is driven in a reverse direction for a predetermined period immediately before developing. 2. In a developing device such as a digital copying machine that uses a two-component developer that is transported from a toner supply port into a developer circulation path by a toner transport screw, the transport screw is reversed for a predetermined period of time after development is completed. A developing device characterized in that it is driven in a direction.