JPS62280782A - Developing device - Google Patents

Abstract

PURPOSE:To secure a good circulation even in case of a magnetic particle whose surface area is large but whose fluidity is bad, by providing plural fixed magnetic field generating means on a contact area of a developer holding member and the magnetic particle in a developer supply container. CONSTITUTION:When fixed magnetic poles 2, 3 are provided in a contact area of a developer holding member 4 and a magnetic particle 7 in a developer supply container 5, the magnet particle 7 is attracted to the developer holding member 4 by the magnetic pole 3, a circulation as indicated with an arrow (c) is repeated by a frictional force by a rotation of the developer holding member 4 and a magnetic force by the magnetic pole 2, and the gravity, and a forced circulation by the magnetic force is secured. In this way, even if an amorphous magnetic particle whose fluidity is bad is used, the circulation is executed satisfactorily, and a developer is supplied enough. Also, by pressure of the magnetic particle in case when the magnetic particle 7 is attracted to the developer holding member 4 by the magnetic pole 3, the residual toner of the development is scraped down, therefore, an uneven image density in a daubed image is also improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing a latent image such as an electrostatic latent image using a non-magnetic developer.

The device disclosed in Japanese Patent Application No. 58-151028 circulates magnetic particles using only one magnetic pole provided on the side of the developer supply container. Only magnetic particles could be used. Since these spherical magnetic particles have a small surface area, they carry a small amount of non-magnetic developer, resulting in a problem in that the amount of developer supplied is small relative to the amount of developer consumed, resulting in uneven image density.

The present invention provides a developing device which eliminates the problems of the conventional example and further reduces developer scattering.

Lord “L’s” L! The present invention includes a developer supply container having an opening, a non-magnetic member for holding developer that is provided in the opening and is movable endlessly inside and outside the container, and a fixed magnetic field generating means provided inside the holding member. , a magnetic particle restraining member provided outside the developer holding member and restraining the magnetic particles inside the developer supply container together with a fixed magnetic field generating means; and a magnetic particle restraining member provided on the developer inlet side of the container forming a magnetic brush. and a sealing member disposed to close a gap between the magnetic member and the developer holding member. The above problem is solved by providing a developing device characterized by having a fixed magnetic field generating means.

1 ejaculation FIG. 1 shows a conventional example.

1 is an electrostatic latent image carrier that moves in the direction of arrow a.

A developer holding member 4 containing magnetic poles 2 and 3 as a fixed magnetic field generating means is disposed with a gap between the latent image carrier 1 and the latent image carrier 1.
is rotatably provided. Reference numeral 5 denotes a hopper as a developer supply container, which accommodates a developer mixture having a non-magnetic developer 6 and magnetic particles 7 together with a developer holding member 4 .

When the developer holding member 4 is rotated in the direction indicated by the arrow, the magnetic pole 2
By appropriately selecting the arrangement position and magnetic flux density of 3 and 3, and the fluidity and magnetic properties of the magnetic particles 7, the developer mixture circulates in the direction of arrow C to form a circulation layer 8.

On the other hand, on the downstream side of the magnetic pole 2 in the rotational direction of the developer holding member 4, a magnetic particle restraining member 9 made of a magnetic material is arranged with a gap maintained between the magnetic particle restraining member 9 and the developer holding member 4. The magnetic particles 7 are restrained on the developer holding member 4 by a balance between gravity, magnetic force, and the conveying force in the moving direction of the magnetic particle restraining member 4, and form a stationary layer 10 that can move a little but is almost immobile. .

A magnetic particle layer consisting of this Oa ring layer 8 and a stationary layer 10 is formed on the surface of the developer holding member 4.The magnetic particle layer contains a non-magnetic developer 6, and the magnetic particles of the stationary layer 10 are The developer holding member 4 is
However, since the developer is non-magnetic, it is not restrained by the magnetic fields of the magnetic poles 2 and 3, and is coated uniformly and thinly on the surface of the developer holding member 4 by the mirroring force, forming a latent image. It is subjected to development while facing the surface of the carrier 1.

In the circulation layer 8, the developer mixture is circulated as shown by arrow C due to the magnetic force and frictional force caused by gravity and magnetic poles, and the fluidity of the magnetic particles, and during this circulation, the magnetic particles are mixed with the non-magnetic developer 6.
The principle of this method of forming a thin layer of developer, in which the developer is taken in and returned to the lower part of the developer supply container 5, and this cycle is repeated thereafter, is detailed in Japanese Patent Application No. 151028/1983 filed by the present applicant, so a detailed explanation will be omitted. .

In the figure, a magnetic member 13 and a sealing member 14 made of a flexible resin sheet arranged to close the gap between the magnetic member 13 and the developer holding member 4 are provided at the bottom of the developer supply container 5. This prevents developer and magnetic particles from leaking from the bottom of the developing device.

In this configuration, in order to supply enough developer to keep up with developer consumption, it was necessary to maintain good movement of the circulation layer, so it was necessary to use roughly spherical magnetic particles with good fluidity. I had no choice. However, in order to maintain good movement of the circulation layer, the amount of non-magnetic developer was still not sufficient, and uneven image density occurred, especially in solid images.

Therefore, the present invention provides an apparatus that improves the drawbacks of the conventional example as described above.

An embodiment of the present invention is shown in FIG. 2. In order to improve the drawbacks of the conventional example described above, (1) magnetic particles with poor fluidity, such as flat or irregular shapes and a large surface area, are used to obtain a good (2) Scrape off the remaining developer on the developer holding member and apply new developer uniformly.

In this example, which will be described in detail below with reference to the drawings, a fixed magnetic pole 2.3 is provided in the contact area between the developer holding member 4 and the magnetic particles 7 in the developer supply container 5.

According to this configuration, the magnetic particles 7 are attracted to the developer holding member 4 by the magnetic pole 3, and the circulation as shown by arrow C is repeated by the frictional force caused by the rotation of the developer holding member 4, the magnetic force by the magnetic pole 2, and gravity. With this configuration, forced circulation by magnetic force was ensured, so good circulation was achieved even when amorphous magnetic particles with poor fluidity were used, and developer supply was also sufficient. . In addition, the pressure of the magnetic particles when the magnetic particles 7 are attracted to the developer holding member 4 by the magnetic pole 3 scrapes off the developer remaining after development, so image density unevenness in solid images is also significantly improved. .

The magnetic pole configuration is not limited to two poles, and if magnetic poles are provided at opposite ends of the magnetic member 13, the magnetic particles can be magnetically attracted to the developer holding member via the sealing member. Adhesion between the sealing member and the developer holding member is increased, and developer scattering from the lower part of the developing device can be further prevented.

As explained above, by providing a plurality of fixed magnetic field generating means in the contact area between the developer holding member and the magnetic particles in the developer supply container, magnetic particles with a large surface area but poor fluidity can be generated. Good circulation could be ensured even when using the developer, and sufficient supply of developer was made possible, thereby preventing uneven image density.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device showing a conventional example, and FIG. 2 is a sectional view of a developing device showing an embodiment of the present invention. 11...Magnetic particle riding prevention member, 12...Development bias power supply.

Claims (1)

[Claims] A developer supply container having an opening, a developer holding non-magnetic member provided in the opening and movable endlessly inside and outside the container, a fixed magnetic field generating means provided inside the holding member, and the developing device. a magnetic particle restraining member provided outside the developer holding member and restraining the magnetic particles within the developer supply container together with a fixed magnetic field generating means; a magnetic member provided on the developer inlet side of the container forming a magnetic brush; A plurality of fixed magnetic fields are generated in a contact area between the developer holding member and magnetic particles in the developer supply container in a developing device having a sealing member arranged to close a gap between the magnetic member and the developer holding member. A developing device characterized by having a means.