JPH077227B2 - Developer carrier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developer carrier for a magnetic developer, and more particularly to a developer carrier applicable to a developing device using a one-component magnetic toner.

2. Description of the Related Art Generally, a developing sleeve provided with a magnet is used as a carrier for carrying a magnetic developer to a developing area. In this case, for example, when the magnet roll is coaxially arranged inside the developing sleeve, the magnet roll tends to be large in size in order to obtain a necessary magnetic force on the sleeve surface. Therefore, as a transporter that is lightweight and can secure the required magnetic force,
As shown in FIG. 1, a developing sleeve 1 in which a magnet layer 2 in which a number of fine magnetic poles are magnetized is formed near the peripheral surface S.
Is proposed. However, the magnet layer 2 in this case
As shown in the drawing, the magnetic poles having polarities different from each other
Along the same plane (in-plane magnetization). In the case of the in-plane magnetized magnet layer 2, a magnetic field is formed along the surface, and the magnetic force lines concentrate near the surface of the magnet layer as shown by the broken line, so that the magnetic flux density decreases sharply as the distance from the surface increases. . Therefore, as shown in the figure, a large number of electrode particles 3a are scattered on the surface of the magnet layer 2 in an electrically insulating state (float state) in order to promote the edge effect in the one-component developer, for example. Developing sleeve 1 in which a floating electrode layer 3 and the like are laminated
In this case, the magnetic flux density on the surface of the float electrode layer 3 (the surface S of the sleeve 1) becomes low, which hinders the transport or thinning of the one-component magnetic toner. Further, in such a magnetizing configuration, it is difficult to magnetize at a small pitch and only the surface layer portion of the magnet layer thickness can be magnetized. Therefore, when a large number of fine magnetic poles are formed within a limited thickness. Would be inconvenient.

Aim The present invention has been made in view of the above points, and provides a developer transporting body that can sufficiently secure a necessary magnetic flux density near the surface, promotes weight reduction, and can be manufactured at low cost. The purpose is to

Configuration Hereinafter, the configuration of the present invention will be described in detail based on specific examples. FIG. 2 is a schematic diagram showing one embodiment of the present invention. In FIG. 2, a dielectric layer 6 made of a dielectric material and a ferromagnetic layer 7 made of a conductive ferromagnetic material having a high magnetic permeability are first formed on the peripheral surface of the cylindrical conductive substrate layer 5. It is sequentially laminated. Further, on the ferromagnetic layer 7, a large number of fine magnetic poles are magnetized substantially evenly along the peripheral surface, and a large number of conductive particles 9a as electrodes support a dielectric material. Float electrode layers 9 which are held in an electrically insulated state from each other and are scattered on the surface layer portion are sequentially laminated in the body 9b. That is, in the phenomenon sleeve 4 of this example, the peripheral surface portion is on the conductive base layer 5 for the dielectric layer 6 and the ferromagnetic material.
7, the magnet layer 8 and the float electrode layer 9 are sequentially laminated to form a five-layer structure. Among these, the conductive base layer 5 and the ferromagnetic layer 7 are connected to the bias power sources 5b and 7b via the switches 5a and 7a, respectively. Therefore, the switches 5a, 7a
Can be appropriately opened and closed to apply an appropriate bias voltage to each of the layers 5 and 7 to appropriately adjust the image quality obtained by the developing device to which the present transporter is applied. The ferromagnetic layer 7 may be held in a float shape.

As described above, the magnet layer 8 has a magnetized structure in which magnetic poles having different polarities are formed in the thickness direction (radial direction) perpendicular to the peripheral surface, as shown in FIG. .
The reason why the magnetic pole is formed in an orientation different from that of the conventional technique is as follows.

When the developing sleeve 4 in which the magnet layer 8 is directly laminated on the ferromagnetic layer 7 is magnetized as in this example, the magnetic force lines (indicated by arrows) applied from the magnetizing yoke Y are the ferromagnetic layer. Since it is short-circuited in 7, the magnet layer 8 is formed in a direction substantially perpendicular to the peripheral surface S.
Therefore, the magnetic poles that are inverted with respect to each other along such lines of magnetic force are magnetized to form the magnet layer 8 in which the magnetic poles are oriented in the thickness direction perpendicular to the peripheral surface S as shown in FIG.

As described above, the lines of magnetic force of the magnetic field formed by the magnet layer 8 in which the magnetic poles that are opposite to each other in the thickness direction are magnetized are, to a certain extent, from the surface S of the magnet layer 8 as shown by the broken line in FIG. Since it extends to the separated areas, even if the float electrode layer 9 is laminated on the magnet layer 8 as in this example, a sufficient magnetic flux density can be secured near the surface of the float electrode layer 9. Therefore, the carrying force of the one-component magnetic developer is strengthened, a desired thin layer is stably formed, and a developing sleeve capable of exhibiting a desired edge effect can be manufactured at a low cost by promoting a reduction in size and weight. . In addition, since the magnetic force on the sleeve surface is strengthened, materials with weak magnetism can be used for layer thickness control members such as doctor blades, which broadens the range of material selection, which contributes to cost reduction and is advantageous for rust prevention of stainless steel, for example. Various materials can be used, which is advantageous for improving overall quality. Further, the developer carrier in which the magnet layer is directly laminated on the ferromagnetic layer can stably obtain the above-mentioned magnetic pole orientation in the thickness direction even if the magnetizing pitch is reduced, and This is suitable for magnetizing a large number of fine magnetic poles within a limited thickness as in this example in that a strong magnetic force can be obtained by magnetizing the entire layer thickness.

Next, another embodiment of the present invention will be described with reference to FIG. In the following embodiments, the same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 4, in the developing sleeve 10 of this embodiment, a rubber magnet layer 12 in which a large number of fine magnetic poles are magnetized on a rubber material is laminated on an elastic ferromagnetic layer 14 containing a rubber material. Therefore, it is suitable as a developer carrier for a latent image carrier such as a photoconductor drum having high rigidity. The ferromagnetic layer 7 is laminated directly on the conductive substrate layer 5 formed on the peripheral surface of the rotating magnet 11 and the dielectric layer 6 in the above-described embodiment is not provided.

Next, still another embodiment of the present invention will be described with reference to FIG. The developing sleeve 13 of this example includes a ferromagnetic layer 14 made of an elastic ferromagnetic material having conductivity on the peripheral surface of the rotating shaft 11.
Is formed, and the rubber magnet layer 12 and the float electrode layer 9 are sequentially laminated on this. Therefore, the rotating shaft 11
Since most of the sleeve 13 excluding the float electrode layer 9 and the float electrode layer 9 is formed of an elastic body, it is effective for a latent image carrier having extremely high rigidity, and also, it is possible to prevent the rotation of the developing sleeve 13 itself. It is possible to absorb the pressure change due to the above.

Next, still another embodiment of the present invention will be described. As shown in FIG. 6, the developing sleeve 15 of this example has a rotating shaft.
A ferromagnetic layer 7 and a magnet layer 8 are sequentially laminated on the peripheral surface of 11, and a large number of ferromagnetic conductive particles 16a as electrodes are scattered on the surface of the magnet layer 8 in a float shape. The float electrode layer 16 is formed. As a result, as shown in FIG. 7, the blade made of a magnetic material is used.
When using a layer thickness control means using magnetic force such as 17
Lines of magnetic force from the magnet layer 8 (shown by broken lines) are applied to the ferromagnetic layer 7, the ferromagnetic conductive particles 16a, and the magnetic blade 17.
A closed magnetic circuit passing through is formed, and the magnetic force of the magnet layer 8 is effectively used for layer thickness regulation. In addition, when magnetizing is performed to obtain a magnetized structure by the present firing in which the magnetic poles are oriented in the thickness direction of the magnet layer 8, the ferromagnetic conductive particles 16
a functions as an extension of the magnetizing yoke Y, which enables efficient magnetizing.

Effect As described above in detail, according to the present invention, by stacking the magnet layer on the ferromagnetic layer, the magnetic poles can be easily oriented and magnetized in the thickness direction of the magnet layer. . Therefore, even in a developer carrier in which a float electrode layer or the like is laminated on a fine multi-pole magnetized magnet layer whose size and weight are promoted, a sufficient magnetic force required near the surface should be ensured. Is possible. In addition, since a sufficient magnetic force is secured, the material selection range of peripheral parts such as the blade is widened, which contributes to lowering the price of the developing device and improving overall quality such as durability. It should be noted that the present invention should not be limited to the above specific embodiments, and various modifications can be made within the technical scope of the present invention.

For example, the magnetized structure of the present invention can be applied to a carrier of a two-component magnetic developer having no float electrode layer.
Further, the carrier is not limited to the sleeve shape, but can be formed in an endless belt shape.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a conventional fine multi-pole magnetized type developer carrier, FIG. 2 is a schematic view showing one embodiment of the present invention, and FIG.
FIG. 4 is an explanatory view showing an essential part of one embodiment of the present invention, FIGS. 4 to 6 are schematic views showing several other embodiments of the present invention, FIG. 7 and FIG. It is each explanatory view showing the operation effect in another example of the present invention, respectively. (Description of symbols) 1,4,10,13,15: Developing sleeve 2,8: Magnet layer 7: Ferromagnetic material layer 12: Rubber magnet layer 14: Elastic ferromagnetic material layer 16a: Magnetic conductive particles

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-55442 (JP, A) JP-A-58-76886 (JP, A) JP-A-58-111067 (JP, A) JP-A-58- 97071 (JP, A) Actual development Sho 58-146249 (JP, U)

Claims (1)

[Claims] 1. A developer transporting body carrying a magnetic developer on a surface thereof and transporting the developer along a predetermined path including a developing region, the ferromagnetic material layer having a high magnetic permeability, and the ferromagnetic material layer. And a magnet layer laminated on the magnet layer, the magnet layer being configured such that different magnetic poles are oriented in the thickness direction of the layer.