JPS6030945B2 - magnetic development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to a developing device applied to an electrophotographic copying machine, and more particularly to an improvement in a magnetic developing device.

Conventional magnetic brush developing devices use toner and magnetic carrier IJ.
A method for developing an electrostatic latent image on the surface of a photoreceptor by attaching a developer with a magnetic brush directly to a permanent magnet and rotating this to develop an electrostatic latent image on the surface of a photoreceptor. Various methods are known, such as a method of forming a brush and developing using this method.

In the former case, the magnetic brush strongly stands up only at the magnetic pole portion of the magnetic roller, resulting in uneven development due to uneven density of the magnetic brush. Further, a removing means such as a scraper is required to remove the developing magnetic brush portion from the surface of the magnetic roller. In the latter case, removal of the magnetic brush portion has been easily solved by rotating the rotating sleeve eccentrically with respect to the magnet and allowing the sleeve to fall naturally when it moves away from the magnet. In this case, the magnetic brushes are formed in a concentrated manner only on the sleeve, especially in the area close to the magnet. Since this magnetic brush bristles quite strongly, the surface of the photoconductor that has been developed once again is rubbed strongly with the magnetic carrier, scraping off the developed image and damaging the image line, and even damaging the surface of the photoconductor. However, since the magnetic carrier strongly rubs the photoreceptor, the life of the photoreceptor is greatly affected. The present invention provides a magnetic developing device which eliminates all of the above-mentioned conventional drawbacks and further allows the formation state of the magnetic brush to be arbitrarily adjusted to perform ideal development.

The present invention is a magnetic developing device in which a developer, a moving non-magnetic material, and a magnetic field generating means are arranged in this order with respect to an object to be developed,
The magnetic field generating means has magnetic poles of the same polarity adjacent to each other at a position facing the object to be developed, and by relatively moving these magnetic poles, the thickness and width of the magnetic brush that stands on the surface of the non-magnetic material can be adjusted. The development area, such as the size of the image, can be freely adjusted.

This makes it possible to arbitrarily adjust the magnetic brush formation according to the developing environment of the electrophotographic copying machine and obtain a good developed image. Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing the structure of a magnetic brush developing device according to the present invention.

In the figure, reference numeral 1 denotes a photoconductor having a latent image of Seishu, which moves in the direction of the arrow. A rotating sleeve 2 is rotatably provided close to the surface of the photoconductor, and magnets 3 and 4 are rotatably provided within the rotating sleeve so that an angle 8 can be adjusted around an axis 5. Magnetic poles of the same polarity are provided adjacent to each other at positions facing the developer. 6 and 7 are developer lamps and 8 is a developer box.

In this configuration, the developer in the developer box is sufficiently spread in the deformers 6 and 7 and is attracted onto the sleeve 2 by the magnetic force of the magnet in the sleeve to form a magnetic brush. The magnetic brush is regulated to have a uniform thickness by the magnetic brush adjustment plate 9, and is then raised again by the magnetic force and applied to the surface of the photoreceptor, thereby developing the electrostatic latent image. At this time, the angle between the magnets 3 and 4 can be arbitrarily adjusted, but good results can be obtained in the range of 600<minus 120o. The developer that has completed development is further moved by the rotation of the sleeve, gradually becomes unaffected by the magnetic force from the magnets 3 and 4, and falls naturally from the sleeve surface due to the centrifugal force of the rotation of the sleeve and its own weight. The developer that has fallen is sufficiently evaporated by the fly rollers 7 and 6 and then used again for development. Next, Figure 2 A,
The shape of the magnetic brush depending on the angle formed by the magnets 3 and 4 in the mouth will be explained.

At this time, the magnetic brush is thick, narrow, and stands strong on the sleeve, which may disturb the image during development. On the other hand, as shown in the diagram, 8 main 1
200, the magnetic brush can be softly raised to a good thickness and width, and an image can be ideally developed during development. When installing the developing device shown in Fig. 1 to a specific electrophotographic copying machine, if sufficient development can be achieved by forming a magnetic brush with a certain shape, the angles of the magnets 3 and 4 may be fixed and installed fixedly. It is also good to do.

As described in detail above, in the magnetic brush developing device of the present invention, since the shape of the magnetic brush can be adjusted to a convenient thickness and width when forming the magnetic brush, a good developing effect can always be obtained.

It should be noted that the developer used herein is applicable to either a developer containing a magnetic carrier and toner or a developer consisting only of magnetic toner.

Furthermore, permanent magnets and electromagnets can also be used as the magnets.

[Brief explanation of the drawing]

FIG. 1 is a structural explanatory diagram showing an embodiment of the magnetic brush developing device of the present invention. FIG. 2B is a diagram showing an embodiment of the device shown in FIG. In the figure, 1 is a photoreceptor, 2 is a non-magnetic sleeve, 3
, 4 is a magnet, and 8 is a developing box. Figure 2 Younger brother l figure

Claims (1)

[Claims] 1. A magnetic developing device in which a developer, a movable non-magnetic material, and a magnetic field generating means are arranged in this order with respect to an object to be developed, in which two magnetic field generating means are provided rotatably around a shaft, and these two magnetic field generating means are rotatable around a shaft. A magnetic developing device characterized in that the opposing magnetic pole surfaces of the magnetic field generating means are of the same polarity.