JPH0614224B2 - Development device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device that can be used in an electrophotographic copying machine, an electrostatic recording type facsimile, and the like.

Configuration of Conventional Example and Problems Thereof FIG. 1 shows a conventional developing device. This conventional example will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a drum-shaped photosensitive member, on the surface of which an electrostatic latent image is formed by a known method. Reference numeral 2 denotes a magnet roll in which a magnet is arranged in a non-magnetic cylindrical sleeve. 3 is a known developer and has an average particle size of 20.
A mixture of a magnetic powder or a magnetic substance having a particle size of μ to 150 μ and a carrier containing a resin as a main component, and a toner containing a resin and carbon black as a main component and having an average particle size of 5 μ to 20 μ. Reference numeral 4 is a doctor blade that keeps the amount of developer on the magnet roll constant. A scraper 5 removes the developer on the magnet roll. 6 and 6'is a stirring member for stirring and mixing the developer peeled off from the magnet roll. Reference numeral 7 is an outer shell of the developing device. Reference numeral 8 is a toner storage tank, and 9 is replenishment toner.

The operation of the conventional developing device configured as described above will be described in detail below. An electrostatic latent image is formed on the photoconductor 1 by a known method, and is rotated in the direction of arrow A. The magnet roll 2 is composed of a cylindrical non-magnetic sleeve 2a and an internal magnet 2b, each of which rotates in the direction of arrow B. It is magnetized to 8 poles and its strength is about 1000 gauss on the sleeve surface. The rotation speed of the sleeve 2a is 110 rpm, and the rotation speed of the magnet 2b is 1300 rpm.
Is. The magnet roll 2 attracts and holds the developer 3 by the magnetic force on the sleeve surface, and develops the latent image on the photoreceptor 1. At this time, the developer on the sleeve 2a is regulated to a constant thickness by the docker blade 4. At the time of development, only the toner in the developer adheres to the latent image on the photoconductor 1. Therefore, the mixing ratio of the carrier of the developer and the toner changes. The developer that has completed development is separated from the magnet roll 2 by the scraper 5 and collected in the developing device. Reference numerals 6 and 6'indicate stirring members which are spiral lead screws or members in which a coil spring is spirally wound around a shaft. The stirring members 6 and 6'rotate in the directions of arrows C and C ', respectively, and the developer is stirred in the opposite directions. At this time, the replenishment toner 9 is replenished from the toner storage tank 8 into the developing device as needed, and the mixing ratio of the carrier of the developer and the toner is made proper. The developer having the proper mixing ratio adheres to the magnet roll 2 again, and the development is repeated.

However, in the stirring member as described above, the movement of the developer in the developing device is mainly the movement of the position from the front side to the back side, from the back side to the front side, and from the upper surface to the lower surface of the developing device. However, the movement from the lower surface to the upper surface was small, and the effect of mixing the developer was very low. If the developers are not mixed well, uneven density will occur in the image, and toner will adhere to the back of the copy, so-called background fog. or,
There is also a drawback that the developing device becomes large in size because two stirring members are required.

SUMMARY OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a small-sized developing device that enables highly efficient mixing of developers.

In order to achieve the above-mentioned object, the developing device of the present invention is provided with at least one opening on the peripheral surface of a rotatable tubular member, and an opening edge portion on the upstream side in the tubular member rotating direction. It has an edge projection protruding to the outer surface, a stirring member is attached to the outer surface of the tubular member, and another stirring member is further provided inside the tubular member. While positively introducing the developer, the effect of stirring and mixing the developer in the vertical direction and the rotational direction is significantly improved.

Description of Embodiments Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view showing the basic structure of the developing device of the present invention. In FIG. 2, 1 is a photoconductor, 2 is a sleeve 2a.
And a magnet 2b, a magnet roll 3, a developer 4
Is a doctor blade, 5 is a scraper, 7 is a contour of a developing device, 8 is a toner storage tank, and 9 is toner for replenishment. 6A, 10 and 11 constitute a stirring device forming a main part of the present invention, 11 is a tubular member having an opening D, 10 is a stirring member disposed inside the tubular member 11,
6A is a stirring member attached to the outer surface of the tubular member 11. Reference numeral 12 is a shaft for rotating the stirring member 10.

Regarding the developing device of the present embodiment configured as described above,
The operation will be described below. First, an electrostatic latent image is formed on the photoconductor 1 by a known method, and is rotated in the arrow A direction. The magnet roll 2 is made of a magnetic material and has a cylindrical sleeve 2a and a magnet 2b incorporated therein. The sleeve 2a and the magnet 2b are configured so that they can rotate independently of each other, and they rotate in the directions of arrows B, respectively. The magnet 2b has a strength of about 1000 gauss on the surface of the sleeve 2a and is symmetrically magnetized into eight poles. The rotation speed of the sleeve 2a is 150 rpm and the rotation speed of the magnet 2b is 1200r.
pm. The developer 3 is attracted to the surface of the sleeve 2a of the magnet roll 2 by magnetic force. Developer 3 is a mixture of carrier and toner. The carrier has an average particle size of 2
It is possible to use a magnetic substance powder of 0 μ to 150 μ, or a powder containing a magnetic substance and a resin as main components. As the toner, those containing resin and carbon black as main components, or those obtained by adding magnetic powder to the above components to add magnetism can be used. In this embodiment, a carrier having a resin and a magnetic material as main components and an average particle diameter of 30 μ and a toner having a resin and a magnetic material as main components and an average particle diameter of 10 μ are used as a developer. The standard mixing ratio of carrier and toner is 75:25 by weight. The developer 3 is regulated by the doctor blade 4 to have a thickness of about 0.7 mm. The developer 3 whose thickness has been adjusted is conveyed to the magnet roll 2 to develop the electrostatic latent image on the photoconductor 1.
The gap between the sleeve 2a of the magnet roll 2 and the photoconductor 1 is about 0.75 mm. Only toner in the developer adheres to the electrostatic latent image due to the development. The developer 3 that has been developed is further conveyed to the magnet roll 2, separated from the surface of the magnet roll 2 by the scraper 5, dropped into the developing device, and collected. Since the developer collected in the developing device consumes toner due to development, the replenishment toner 9 stored in the toner storage tank 8 is replenished in the developing device in an appropriate amount. The developer that has completed development and the replenished toner are sufficiently mixed and stirred by a stirring device. The stirring device according to the present invention includes a tubular member 11, an internal stirring member 10 and an external stirring member 6A. The tubular member 11 is provided with an opening D. This opening D is for the developer 3 in the developing device to enter and leave the inside of the tubular member 11. As will be described later with reference to FIG. It projects to the outside. The stirring member 6A is a spiral member provided on the outer surface of the tubular member 11 and rotates integrally with the tubular member 11 in the direction of arrow C. The stirring member 10 is a spiral member provided inside the stirring member 11, and is twisted in the opposite direction to the stirring member 6A and rotated in the direction of arrow C by the shaft 12. A part of the developer separated from the magnet roll 2 by the scraper 5 enters the inside through the opening D of the tubular member 11 and is stirred by the stirring member 10.

On the other hand, the other part which is also separated from the magnet roll 2 falls outside the tubular member and is stirred by the stirring member 6A. The developer is conveyed in opposite directions by the stirring members 10 and 6A, so that the mixing ratio of the toner carriers is dispersed in the developing device.

At the same time, the replenishment toner 9 dropped from the toner replenishment tank 8 is also mixed with the developer inside and outside the tubular member 11 by the stirring members 6A and 10. The developer in the tubular member 11 is
When the opening D of the above is located at the substantially lower position, it flows out from the inside of the tubular member 11 to the outside. As a result, the developer 3 can be stirred and mixed in the vertical direction in the developing device, and can be stirred and mixed in the front-rear direction by the stirring members 6A and 10 to be extremely uniform and efficient. Developer 3 mixed with stirring
Is attracted to the magnet roll 2 again, the thickness thereof is adjusted by the doctor blade 4, and the electrostatic latent image on the photoconductor 1 is developed.

As described above, according to the present embodiment, the developer is diverted into and out of the tubular member 11, the developer is mixed while being conveyed in opposite directions, and further, the opening D enables the conveying and mixing in the vertical direction. Very uniform and efficient mixing,
Stirring is performed to enable uniform development and development without background fog. In the above embodiment, the toner and the carrier of the developer are mainly composed of the resin and the magnetic material, and the magnet roll is the one that rotates both the sleeve and the magnet. However, the invention is not limited to these. Rather, it is only necessary that one of the carrier and the toner has magnetism, and the mixture has the property of being adsorbed by the magnet, and the magnet roll is not limited as long as one of the sleeve and the magnet can rotate. Good. Further, the scraper 5 is not always necessary, and the point is that the developer may enter the inside of the tubular member 11.

Further, as illustrated in FIG. 3, the opening D of the tubular member 11 is formed.
By bending the edge portion 11A on the upstream side with respect to the rotation direction of the tubular member outward, a large amount of the developer can be introduced into the opening D, and at the same time, the developer can be introduced in the rotation direction. Stirring efficiency is also improved. Further, the effect of effectively supplying the developer onto the magnet roll can be obtained.

Further, by attaching the stirring member 10 to the inner surface of the tubular member 11 so as to rotate integrally therewith, there is no need to rotate the stirring member 10, and the developing device can be further simplified.

13, 14, and 15 shown in FIGS. 4, 5, and 6 are examples of stirring members that can be used in the stirring members 10 and 6A of the present invention. The effects of the present invention can be obtained even if the tubular members are used in any combination depending on the size of the tubular member, the amount of the developer, and the number of rotations. Although the opening D is provided from one end of the tubular member 11 to the other in FIG. 3, it may be provided separately or in a spiral shape. Further, a plurality of members may be provided around the tubular member depending on its size. In this embodiment, the tubular member is described as having a cylindrical shape, but the tubular member is not limited to the cylindrical shape, and the developer flow can be temporarily separated into the inside and the outside,
Further, it is sufficient if it has an opening that allows access.
For example, it may be a polygon such as a substantially hexagon.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, an opening is provided in a tubular member, and an edge protrusion protruding from the outer surface of the tubular member is formed at one of the edges of the opening, and the stirring member is provided inside and outside. Since the developer can be stirred not only in the axial front-back direction but also in the rotation direction and the vertical direction, the excellent effect that the mixing and stirring of the developer is efficient and uniform Is obtained. 2 on the concentric axis
Since the stirring member of some kind is provided, there is an effect that the developing device can be downsized. In addition, since an edge protrusion is provided on the edge of the opening on the upstream side of the rotating direction of the tubular member, the developer is effectively introduced into the opening, and the stirring effect in the rotating direction is also included. Is improved.

[Brief description of drawings]

1 is a sectional view of a conventional developing device, FIG. 2 is a sectional view of a developing device according to an embodiment of the present invention, and FIG. 3 is a perspective view showing another example of a tubular member usable in the present invention. FIG. 4, FIG. 5 and FIG. 6 are perspective views showing examples of stirring members that can be used in the present invention. 6A, 10, 13, 14, 15 ... Stirring member, 11 ...
Tubular member, D ... Opening.

Claims (2)

[Claims] 1. A tubular member, which is rotatable and has at least one opening on its peripheral surface, and has an edge protrusion protruding to the outer surface at the edge of the opening on the upstream side with respect to the rotation direction, and the tubular member. A developing device comprising a first stirring member disposed inside the member and a second stirring member disposed on an outer surface portion of the tubular member. 2. One of the first stirring member and the second stirring member is integrally attached to the tubular member, and the first stirring member and the second stirring member rotate by different power sources. The developing device according to claim 1, wherein: