JPS5952267A - Developing device - Google Patents

Abstract

PURPOSE:To prevent toner from lumping on a conveyance path and to obtain a clear picture, by confronting the toner with a magent roll right before the holding amount of toner to a sleeve is specified, and conveying the toner onto the sleeve. CONSTITUTION:The toner 3 in a hopper 5 flows depending on the slanting angle R of a plate 9 and the flowability of the toner 3, and is supplied onto the sleeve 1 by the magnetic force of the magnet roll 2 and supplied to a development area. In this case, the toner 3 is confronted with magnet poles 21 and 22 of the roll 22 before the holding amount of toner 3 to the sleeve 1 is specified, and conveyed on the sleeve 1. The magnet poles 21 and 22 have the same polarity and a repulsive magnetic field is estabilished in this area 10; and the toner 3 is stirred while jumping over the sleeve 1 to prevent its lumping and conveyed to the development area after being specified by a specifying plate 6 to a specific amount.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for visualizing an electrostatic latent image formed on a photoreceptor in an electrophotographic copying machine, and in particular to a developing device made of a magnetic one-component toner. The present invention relates to a developing device that performs development using a developer.

The developing device of an electrophotographic copying machine uses a two-component developer consisting of a colored pigment toner and a magnetic carrier such as iron powder.The toner is charged electrostatically on the photoreceptor by frictional charging between the toner and the carrier. One type uses a method in which the toner is charged to the opposite polarity to the latent image and adheres to the electrostatic latent image, and the other uses a one-component developer in which the toner itself has magnetic properties. There is a method in which toner is electrostatically attracted to an electrostatic latent image by applying dielectric polarization or the like. A magnetic brush development method is widely used as a developing means for conveying a two-component or -component developer to the development area of the photoreceptor on which an electrostatic latent image is formed and attaching toner. ing. This development method has advantages over the cascade development method, such as a simpler structure and smaller size. The magnetic brush development method generally uses a developing roller consisting of a cylindrical sleeve made of a non-magnetic material and a magnet roller rotatably installed inside the sleeve. The rotation causes the carrier or magnetic toner to be attracted onto the sleeve by magnetic force, and the developer is conveyed to the development area.

The developing device having the above-mentioned structure uses a two-component developer, and requires means separate from the developing roller for stirring the developer in order to triboelectrically charge the toner.

However, those using a -component type developer do not need to provide stirring means for frictionally charging the toner, and can be more compact than two-component type developing devices.

Here, a problem with a magnetic brush type developing device that uses a -component type developer (hereinafter referred to as toner) is the agglomeration of the toner. That is, the fluidity (angle of repose) of -component magnetic toner varies depending on the content of magnetic powder, the type of resin, etc., but since it is a fine particle, it clumps when passing through a narrow area. Further, the toner particles may be frictionally charged with each other or between the toner particles and the sleeve, and may be electrostatically aggregated, or the toner particles may be magnetized and aggregated by the magnetic force of the magnet roller.

If the toner hardens due to the reasons mentioned above, normal development becomes impossible and good images cannot be obtained. Normally, a regulating means is provided to regulate the amount of toner held on the sleeve of the developing roller, and this regulating means, the path for conveying the toner to the developing roller, and the developing area are very narrow, and the above-mentioned toner clumps are likely to occur. Moreover, it was difficult to prevent this.

In view of the above-mentioned drawbacks, the present invention provides a developing device in which toner does not clump, and achieves the object with a simple structure.

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

FIG. 1 is a sectional view showing a specific example of a developing device according to the present invention. In the figure, 1 is a cylindrical sleeve made of non-magnetic material;
Reference numeral 2 denotes a magnet roller which is rotatably provided within the sleeve and whose outer circumferential magnetic poles except for a portion are sequentially magnetized, and these constitute a developing roller. Reference numeral 3 denotes a one-component magnetic toner held on the sleeve 1 by the magnetic force of the magnet roller 2. Reference numeral 4 denotes a photosensitive toner that is rotated in the direction of the arrow and positioned through the layer of the sleeve 1 and toner 3 to form an electrostatic latent image. It is a body drum. The toner 3 is stored in a hopper 5 for replenishment, flows through an inclined plate 9 having an inclined surface of an angle R provided in an opening 8 at the bottom of the hopper 5, and is caused to flow into a sleeve by the magnetic force of the magnet roller 2. 1 sequentially.

On the other hand, a developing area facing the photosensitive drum 4 and a hopper 5
A regulating plate 6 is arranged at a distance A from the sleeve 1 to regulate the amount of spikes (holding amount) of the toner 3 supplied onto the sleeve 1. The regulating plate 6 controls the amount of toner 3 held on the sleeve 1 in order to always convey a constant amount of toner to the development area where the toner 3 contacts the surface of the photoreceptor drum 4 . The regulating plate 6 is fixed to one side wall 7 constituting the hopper 5, and controls the amount of toner replenished from the opening 8 of the hopper 5 as described above. The magnet roller 2 facing the opening 8 of the hopper 5 before the regulating plate 6 regulates the amount of toner 3 held has a magnetic pole structure in which adjacent magnetic poles 21 and 22 are of the same polarity. The magnet roller 2 is fixed and the sleeve 1 on its outer periphery rotates in the direction of the arrow, thereby conveying the toner 3 to a developing area facing the photoreceptor 4 . -1. The magnetic flux density of each magnetic pole of the magnet roller 2 is, for example, the second
It has the characteristics as shown in the figure. The magnetic poles 21 and 22 constituting the magnet roller 2 are opposed to the opening 8 of the toner replenishing part of the hopper 5 with an interval of the corner 2, but are limited to the positions shown in the figure. Rather, it is provided in front of the regulating plate 6 and facing the part where toner is replenished.

The operation of the device configured as described above will be explained for the purpose of understanding the present invention.

The toner 3 in the toner supply hopper 5 now flows due to the inclination angle R of the inclined plate 9 and the fluidity (angle of repose) of the toner 3.
It is supplied onto the sleeve 1 by the magnetic force of the magnet roller 2, and as the sleeve 1 rotates in the direction of the arrow (■), it is conveyed to the developing area. At this point, the toner 3 passes through the regulating plate 6 and the developing area, making it easy to clump. The fluidity (
Although the angle of repose is different, the toner particles 3 are frictionally charged with each other or the toner particles and the sleeve 1 and coagulate electrostatically, or the toner particles 3 are magnetized by the magnetic force of the magnet roller 2 and coagulate.

However, in the present invention, the toner 3 faces the magnetic poles 21 and 22 of the magnet roller 2 and is conveyed on the sleeve before the regulating plate 6 regulates the amount of toner 3 replenished from the hopper 5 that is held in the sleeve 1. Toner 3 generated by
Breaks the lumps (agglomerations) and prevents the formation of lumps. That is, since the magnetic poles 21 and 22 have the same polarity, a repulsive magnetic field is generated in this region 10. Because of this repulsive magnetic field, if the toner 3 faces the distance between the magnetic poles 21 and 22,
The toner 3 jumps on the sleeve without moving on the sleeve 1 and is simultaneously stirred, breaking up the agglomerated toner and preventing the toner 3 from clumping. This resolved toner 3 is conveyed by the sleeve 10 rotations, is regulated to a constant amount via the regulation plate 6, and reaches the development area. The toner 3 that reaches this development area is free from agglomerations and is subjected to development in a stable state. Incidentally, the repulsion magnetic field generated in the above region 10 can be made stronger by reducing the interval angle Z with respect to the magnetic poles 21 and 22, and the action force for stirring and the like can be increased.

In one embodiment, a toner regulating plate 6 and a spring 1 are provided.
interval AkO, 2~],, 0-, the weight ratio of iron oxide powder and styrene resin is 5:5 or 6:4, and the particle size is 5~
Using toner 3 with a repose angle of 40 to 45 degrees, the development pole 23 facing the development area is 1000 Gauss, the magnetic pole 21.22 is 700 Gauss, and the angle Z is 35
When using the magnetic roller 2 configured as follows, no clumping of the toner 3 was observed, the toner was smoothly conveyed, and a good image was obtained.

As explained above, according to the developing device of the present invention, the toner clumps that occur in the path for conveying the toner to the developing area are prevented by using the repulsive force of the magnetic poles of the magnet roller, and the toner is conveyed smoothly. In addition, the amount of toner conveyance can be accurately controlled, and clear images can always be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a specific example of the developing device according to the present invention.
FIG. 2 is a characteristic diagram showing the magnetic flux density of each magnetic pole of the magnet roller of the present invention in FIG. Photoreceptor, 5: hopper, 6: regulation plate, 8: opening.

Claims (1)

[Claims] 1. A developing roller consisting of a cylindrical sleeve made of a non-magnetic material and a rotatably provided magnetic roller is used, and the sleeve and the magnetic roller are rotated relative to each other to develop a magnetic one-component system. In a developing device that holds developer on a sleeve and conveys it to a developing area facing a photoreceptor on which an electrostatic latent image is formed, toner is removed before a regulating plate that regulates the amount of developer retained on the sleeve of the developing roller. A developing device in which adjacent magnetic poles of the magnetic roller facing the replenishment reservoir have the same polarity, the magnetic roller is fixed, and the sleeve is rotated.