JPH0466355B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic brush developing device, and in particular,
This invention relates to a magnetic brush developing device which constantly and evenly mixes a developer (developer) and replenishment toner to obtain copies without uneven density.

[Prior art]

Usually, in a magnetic brush developing device, the amount of developer picked up on a developing roll (mag roll) is controlled by a developer control plate (trimmer plate). In order to better mix the surplus developer with toner newly supplied from outside the developing machine, a configuration is often adopted in which a conveying plate is used to convey the excess developer to the toner replenishing section.

That is, as an example is shown in FIG. 1, the developer 1 is put into the developing machine 2 and is held in the state shown by the dotted line. By the paddle wheel 3, the developer 1 is picked up onto the developing roll 6 by the pick-up magnetic pole 5 of the magnet roll 4, and is conveyed upward by the rotation of the developing roll 6. And trimmer plate 7
Then, the developer 1 is controlled to an appropriate amount and is conveyed to the electrostatic latent image area on the photoreceptor drum 8. On the other hand, the surplus developer 1 regulated by the trimmer plate 7 is guided by the conveyor plate 9 to a toner dispense roll 10 that supplies replenishment toner, and here, it is fed from the toner dispense roll 10. Mixed again with new toner. The developer 1 conveyed to the electrostatic latent image section forms brush-like spikes according to the magnetization pattern of the developing magnetic pole 11, and creates an optimally set developing space 1.
2, the electrostatic latent image on the photoreceptor drum 8 is developed. By depositing toner on the electrostatic latent image, one of the toner
The developer which has lost its portion is transported along with the rotation of the developing roll 6, and when it comes to the pick-off magnetic pole 13, it is picked off by the centrifugal force and the repulsion magnetic field. Then return to paddle wheel 3.

By the way, in this developing machine, the conveying plate is usually made of an aluminum plate, etc., but in this case, it is affected by the magnetic force of the magnet roll in the developing roll,
The flow of developer on the conveyor plate fluctuates, and although this is influenced by the angle of the conveyor plate, there are times when it stops flowing at all, and the amount of developer toner supplied to the paddle wheel 3 together with new toner varies greatly. There was an inconvenience that copy density was uneven.

Further, the developing device shown in FIG. 2 uses a pipe containing an auger 21 in place of a dispense roll for supplying replenishment toner to supply new toner. In this developing device, the excess developer 1 scraped off from the developing roll by the trimmer plate 7 is transferred to the auger 21 by the conveying plate 9.
The toner is mixed with new toner by an auger and supplied to the paddle wheel 3. This auger 21 is shown in FIG. 3 as an outline of its main parts and peripheral parts as seen from direction A in FIG.
It is arranged near the lower end of the conveyance plate 9,
It has a developer supply port 22 near the guide piece _9A provided at a part of the lower end of the conveyor plate 9, and is surrounded by a pipe 24 having a toner supply port 23 for supplying new toner on the outside thereof. . Furthermore, this pipe 24 is equipped with a slit 25 that is opened to gradually become wider in the same direction as the conveyance direction A in the developer perforation of the auger, and as the auger 21 rotates, the toner is supplied from the toner supply port 23. The new toner and the surplus developer supplied from the developer supply port 22 are mixed and supplied to the paddle wheel 3 from the slit 25. This supply amount is the fourth
As shown by the dotted line a in the figure, it is desirable that the thickness be uniform in the axial direction of the auger 21. however,
Since the conveyor plate 9 is usually made of an aluminum plate, the flow of the developer on the conveyor plate 9 is likely to change due to the magnetic influence of the mag roll, and the flow rate of the developer flowing into the developer supply port 22 changes. , in fact, the fourth
As shown by solid lines b and c in the figure, it was non-uniform in the axial direction. b is the developer supply port 2
When the amount of developer flowing into 2 is too large,
On the other hand, when c is too low, the amount of developer to the paddle wheel (mixed with new toner)
The distribution of the amount of falling (supply amount) is shown. If the amount of developer perk supplied to the paddle wheel is uneven as described above, there is a problem in that the density of the copy becomes uneven.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and
To provide a magnetic brush developing device which can maintain a constant flow of a developer on a conveying plate for conveying the developer from a trimmer plate to a toner replenishing part and obtain a good copy image without density unevenness.

[Structure of the invention]

In order to achieve the above object, in the magnetic brush developing device of the present invention, a portion or the entire transport plate is made of a magnetic material.

As a result, the flow rate of the developer on the conveying plate is always kept constant without being affected by the magnetic change of the mag roll, so it is possible to supply the developer evenly and uniformly.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 5, this developing device includes a conveying plate 9' for conveying the surplus developer scraped off from the developing roll by the trimmer plate to the position of the toner dispense roll.
is composed of a magnetic plate, and the other composition is the first
This is similar to the conventional developing device shown in the figure.

That is, the developing device according to the embodiment of the present invention has a developing roll 6 equipped with a magnet roll 4 therein, and a paddle wheel 3 that mixes the developer roller 1 better, triboelectrically charges it, and supplies it to the developing roll 6.
and a trimmer plate 7 that regulates the amount of developer adhered to the developing roll 6 prior to development;
A conveyance plate 9 made of a magnetic plate for conveying the excess developer removed by the trimmer plate 7, and a toner dispense roll 10 disposed at the end of the conveyance plate for replenishing new toner. The surplus developer conveyed by the conveyance plate 9 falls while mixing with new toner supplied by the toner dispense roll 10,
The mixture is again mixed by the paddle wheel 3 and supplied to the developing roll.

The magnet roll 4 also attracts the developer 1 and supplies toner to a pick-up magnetic pole 5 for adhering to the surface of the developer roll and an electrostatic latent image portion on the photoreceptor drum 8 to form a visible image. A developing magnetic pole 11 is provided, and a pick-off magnetic pole 13 is provided for removing developer remaining from the surface of the developing roll after development.

According to this configuration, the excess developer scraped off from the surface of the developing roll 6 by the trimmer plate 7 is blocked from the influence of the magnetic field by the magnet roll 4 by the conveying plate 9 made of a magnetic plate. Therefore, it flows evenly over the conveyance plate 9. This developer mixes with new toner supplied by the toner dispense roll 10 and falls, is uniformly stirred by the paddle wheel 3, is frictionally charged, and is guided to the developer roll 6. . Therefore, the flow of surplus developer is always constant, and this is mixed with new toner, and the same amount of developer is always mixed evenly at the paddle wheel 3, so there is no density unevenness. It becomes possible to obtain a clear copy image without causing any distortion.

Next, other embodiments of the present invention will be described.

As shown in FIG. 6 as a schematic diagram and as shown in FIG. 7 as an enlarged view of the main part viewed from the direction of arrow B in FIG. The developing device is constructed by attaching a plate 26, and the other structure is the same as that of the developing device shown in FIGS. 2 and 3.

That is, in this device, the developer flows on the magnetic plate 26 without being affected by the magnetic field of the magnet roll, so the developer flowing into the developer supply port 22 of the pipe 24 is always constant, and the developer is supplied from the toner supply port 23. The toner is mixed well with new toner by the auger, and is transported through the slit 25 and dropped onto the paddle wheel 3 while maintaining uniformity in the axial direction. Then, at the paddle wheel 3, the toner is mixed even better with the developer located there, and then supplied to the developing roll 6, so that a clear copy image without density unevenness can be obtained.

In addition to the structure shown in the examples, the structure of the conveyor plate may be one in which a magnetic plate is glued to the entire back side of a normal aluminum plate, or a structure in which a magnetic plate and a normal aluminum plate are glued together. It can be selected as appropriate.

〔Effect of the invention〕

As explained above, according to the present invention,
Part or all of the conveying plate for conveying the surplus developer scraped off from the developing roll to the new toner replenishment port under the control of the trimmer plate is made of a magnetic material. A constant amount of developer is always conveyed without being affected by the magnetic field of the magnet roll. This developer is mixed with new toner and supplied to the paddle wheel as a constant amount of uniform developer, making it possible to obtain a clear copy image without uneven density.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing a conventional magnetic brush developing device, Figure 3 is an enlarged view of a portion seen from direction A in Figure 2, and Figure 4 shows the distribution of the developer supply amount. 5 is a diagram showing a magnetic brush developing device according to an embodiment of the present invention, FIG. 6 is a diagram showing a magnetic brush developing device according to another embodiment of the present invention, and FIG. 7 is a diagram showing a magnetic brush developing device according to another embodiment of the present invention. It is a partially enlarged schematic diagram seen from direction B. 1...Developer, 2...Developer, 3...
Paddle wheel, 4... Magnet roll, 5...
...Pickup magnetic pole, 6...Developing roll, 7...
Trimmer plate, 8... Photosensitive drum, 9...
Conveyance plate, 10... Toner dispense roll, 11... Development magnetic pole, 12... Development space, 13
...Pick-off magnetic pole, 21...Auger, 22...
... Developer supply port, 23 ... Toner supply port, 24 ... Pipe, 25 ... Slit, 9 _A ...
...Guide piece, 9'...Transportation plate, 9''...Transportation plate, 26...Magnetic plate.

Claims (1)

[Claims] 1. In a magnetic brush developing device, the developer adhering to the developing roll is regulated by a developer control plate, and the magnetic brush developing device is equipped with a conveying plate that conveys the surplus developer generated by the regulation to a toner replenishing section, A magnetic brush developing device characterized in that a part or the whole of the conveying plate is made of a magnetic material.