JPS6226465B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a carrierless (one-component system) magnetic brush developing device for electrophotography using magnetic toner made by dispersing a magnetic material in a resin material. be.

[Conventional technology]

Magnetic toner does not require a carrier, unlike the commonly used two-component developer consisting of a mixture of non-magnetic toner (resin component) and magnetic carrier, so there is no need to worry about carrier fatigue.
In addition, it has many advantages, such as not requiring a means to improve the frictional charging between the toner and carrier or a mixing means to obtain a uniform toner concentration.
It has recently become known.

On the other hand, as a developing device using this magnetic toner, the one shown in FIGS. 1 and 2 is known.
That is, a rotatable sleeve 2 is disposed partially inside a hopper-shaped toner storage tank 1, and a magnetic field generator 3 in which an appropriate number of permanent magnets are fixedly arranged concentrically is installed inside the sleeve. 2 in the direction of arrow A, the magnetic toner 4 in the storage tank 1 is transferred while adhering to and transferred to the surface of the sleeve 2 by the magnetic absorption action of the magnetic field generator 3. The height is regulated by a regulating plate 5, and the magnetic toner 4 reaches the developing section 6 at a position above the main magnet _M1 of the magnetic field generator 3 facing the electrostatic latent image support 7.
The magnetic toner stands up and comes into sliding contact with the electrostatic latent image support 7, and the magnetic toner is attached to the electrostatic latent image, thereby developing the electrostatic latent image.

The magnetic force of the magnetic field generator 3 used in this developing device is such that the main magnet M ₁ has a strong magnetic force to improve the stacking, and the other conveyor magnets M ₂ , M ₃ , M ₄
The magnetic force is also strengthened for conveyance force and prevention of scattering, and the combination of these magnetic lines of force improves the standing of the developing area.For example, the magnetic force of the main magnet is 1400 gauss, and the magnetic force of the other conveyor magnets is 1400 gauss. The magnetic force is set to 1000 Gauss.

[Problem that the invention seeks to solve]

Therefore, the magnet located in the storage tank 1, that is, the first
_The magnetic force of the magnets M ₂ and M ₃ in the figure or the magnet M ₃ in FIG. 2 is the same as that of the magnet M ₄ in FIG.
Since it is similar to the magnetic force of _M4 , the conveying force due to the magnetic force in the storage tank 1 becomes stronger, the amount of magnetic toner 4 scraped off by the regulating plate 5 increases, and the front surface 8 of the regulating plate 5 increases.
As the magnetic toner 4 accumulates and is used repeatedly, the agglomeration of the magnetic toner 4 progresses, leading to problems such as poor conveyance and poor stacking in the developing section 6, resulting in poor developability.

Furthermore, if the magnetic force of the magnets (M ₂ and M ₃ in FIG. 1 or M ₃ in FIG. 2) in the storage tank 1 is set to 0, then the unloading magnet near the outside of the regulating plate 5 (in FIGS. 1 and 2) Since the magnetic force of M ₄ ) is not directed into the storage tank 1, there arises a drawback that the magnetic toner 4 is difficult to draw out.

[Means for solving problems]

Therefore, the present invention solves the above-mentioned drawbacks.
A magnetic field generator having a plurality of magnetic poles is fixed in a rotatable non-magnetic sleeve that is partially inserted into the one-component magnetic toner storage tank, and a regulating plate is provided at the toner outlet below the sleeve. In the magnetic brush developing device, the magnetic force of the magnetic pole of the magnetic field generator located in the one-component magnetic toner storage tank is set to 1/2 to 1 of the magnetic force of the discharge magnetic pole located downstream of the regulating plate in the toner transport direction. /10.

〔Example〕

An embodiment shown in FIG. 3 will be described below.

11 is a one-component magnetic toner storage tank, 12 is a rotatable non-magnetic sleeve partially inserted into the storage tank 11, and 13 is a permanent magnet magnetic pole M ₁₁ .
A magnetic field generator having M ₁₂ , M ₁₃ , and M ₁₄ is fixed concentrically within the sleeve 12 . 14 is a magnetic toner formed by dispersing a magnetic material in a resin, 15 is a regulating plate provided at the outlet of the storage tank 11, 16 is a developing section, and 17 is an electrostatic latent image support.

The magnetic pole _M11 of the magnetic field generator 13 is a main magnetic pole facing the electrostatic latent image support 17, and the magnetic pole _M12 stores the one-component magnetic toner remaining in the non-magnetic sleeve 12 after development. The magnetic pole M13 is a carry-in magnetic pole carried into the tank 11, and the magnetic pole _M13 is a magnetic pole located in the one-component magnetic toner storage tank 11.
A magnetic pole M ₁₄ located downstream of the regulating plate 15 in the toner transport direction between the main magnetic toner M ₁₃ and the main magnetic toner M ₁₁ is a one-component magnetic toner carried out from the one-component magnetic toner storage tank 11 by the non-magnetic sleeve 12 . Magnetic toner main pole M ₁₁
The magnetic force of the main magnetic pole M ₁₁ , the carry-in magnetic pole M ₁₂ , and the carry-out magnetic pole M ₁₄ is approximately the same as that of the corresponding conventional magnetic poles, and
The magnetic force of _M13 is set to 1/2 to 1/10 of the magnetic force of the output magnetic pole _M14 .

In this way, the magnetic pole M ₁₃ located inside the storage tank 11
The reason why the magnetic force is set to 1/2 to 1/10 of the magnetic force of the carry-out magnetic pole _M14 located downstream of the regulating plate 15 in the toner transport direction is because if the magnetic force is larger than 1/2, the toner near the regulating plate 15 is If aggregation progresses and the magnetic force is smaller than 1/10, the toner transport force will drop too much and a sufficient amount of toner cannot be supplied to the developing area. If the amount of electric charge that the toner particles have within the toner particles becomes too large, they tend to stick to various parts of the non-magnetic sleeve 12 and storage tank 11, and this tendency becomes more noticeable the longer the toner transport process continues. In order to alleviate this, it is necessary to peel off some of the toner from the top of the non-magnetic sleeve 12 and replace it with the toner in the toner storage tank 11. The toner stripping effect becomes too small, and the toner is subjected to frictional charging on the non-magnetic sleeve 12 for a long time, has too much charge, and tends to stick to the non-magnetic sleeve 12 due to image force. This is because if the magnetic force is smaller than that, the effect of stripping the toner from the non-magnetic sleeve 12 becomes too large, and the number of lines of magnetic force between the output magnetic poles _M14 decreases, resulting in a decrease in conveyance performance.

In the above embodiment, the number of magnetic poles located in the storage tank 11 is one _M13 , but if there are two or more magnetic poles, their magnetic force is reduced to 1/2 to the magnetic force of the exported magnetic pole _M14 .
Make it 1/10.

The present invention reduces the magnetic force of the magnetic pole M ₁₃ located in the storage tank 11 to 1/2 to 1/10 of the magnetic force of the magnetic pole M ₁₄ as described above.
Therefore, when the sleeve 12 is rotated in the direction of arrow A, the magnetic toner 14 in the storage tank 11 moves to the magnetic pole M ₁₃
Due to the magnetic force of the toner, the toner adheres to the surface of the sleeve 12 and is carried out from the toner outlet.However, since the magnetic force of the magnetic pole _M13 is weaker than that of the carry-out magnetic pole _M14 , the amount of toner that adheres to the surface of the sleeve 12 is small. Less amount is scraped off.

The magnetic toner 14 attached to the surface of the sleeve 12 and discharged from the toner outlet has magnetic poles M ₁₄ and M _{11 .}
, the sleeve 12 is transported while adhering to the surface and being dislocated, reaching the developing section 16 and forming a magnetic pole.
The magnetic toner 14 stands up due to the magnetic force of M ₁₁ and slides into contact with the electrostatic latent image support 17 rotating in the direction of arrow B to develop the electrostatic latent image, and the remaining magnetic toner 14 is transferred to the magnetic pole M _{12 .}
While being subjected to the magnetic force of , it adheres to the surface of the sleeve 12 and is dislocated, and is returned to the storage tank 11 again.

In this case, since the magnetic poles M ₁₁ , M ₁₂ , and M ₁₄ have the same magnetic force as in the conventional case, the state of standing up in the conveying and developing section 16 is maintained as well as in the conventional case.

〔Effect of the invention〕

Since the present invention is configured as described above, the amount of magnetic toner that adheres to the sleeve and is transported toward the regulating plate in the magnetic toner storage tank is small.
The amount of toner scraped off by the regulating plate is small, and excessive pressure is not applied by the magnetic toner conveyed to the regulating plate of the storage tank, and agglomeration does not occur near the regulating plate. Because the magnetic toner is always well-developed, the developing performance is maintained well, and the magnetic force of the magnetic pole in the magnetic toner storage tank is weak, the remaining toner after development and the toner in the magnetic toner storage tank are kept at a suitable level. Furthermore, since the magnetic force of the ejection magnetic pole located downstream of the regulating plate in the toner transport direction is moderately stronger than the magnetic force of the magnetic pole located inside the magnetic toner storage tank,
This is an excellent invention that allows for the delivery of sufficient toner necessary for development.

The device of the present invention is fully effective when using magnetic toner.

In addition, in the case of the present invention, since the magnetic toner is only consumed through use, the magnetic toner storage tank is of a type without a hopper as shown in FIG. 3, so that a fixed amount of copies can be made. When a problem occurs, only the storage tank is replaced and there is no need to replenish toner or replace the carrier as in the conventional method, which is advantageous in that there is no risk of fine particles of developer scattering inside the device.

[Brief explanation of the drawing]

1 and 2 are schematic cross-sectional side views showing respective embodiments of a conventional magnetic brush developing device, and FIG. 3 is a schematic cross-sectional side view showing an embodiment of the present invention. 11...Magnetic toner storage tank, 12...Sleeve, 13...Magnetic field generator, 14...Magnetic toner,
15...Regulation plate, _M11 , _M12 , _M13 , _M14 ...Magnetic pole.

Claims (1)

[Claims] 1. A magnetic field generator having a plurality of magnetic poles is fixed in a rotatable non-magnetic sleeve that is partially inserted into a one-component magnetic toner storage tank, and is regulated at a toner outlet below the sleeve. In a magnetic brush developing device provided with a plate, the magnetic force of the magnetic pole of the magnetic field generator located in the one-component magnetic toner storage tank is set to 1/2 to 1/2 of the magnetic force of the discharge magnetic pole located downstream of the regulating plate in the toner transport direction. An electrophotographic magnetic brush developing device characterized by being 1/10 scale.