JPS6021074A - magnetic brush developing device - Google Patents

Abstract

PURPOSE:To prevent the generation of toner stagnation with simple constitution while satisfying a condition obtaining an excellent developing characteristic by opposing cylindrical roller provided with plural projections to a magnet roller. CONSTITUTION:The cylindrical guide roller 18 provided with plural projections forming a projected part 21 and a recessed part 20 is arranged in a developing area A so as to be opposed to the magnet roller 13 forming a magnetic brush. Consequently, a gap (a) narrower than a gap (b) formed by a doctor blade 19 is held in the area A by the projected part 21 and the stagnation of the toner in an area B just before the area A is not generated by the gap difference because a developer passes through the recessed part 20. Thus, the toner is prevented from being stagnated with the simple constitution while satisfying the condition obtaining the excellent developing characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic brush developing device used in dry electrophotographic development.

Conventional configuration and its problems FIG. 1 shows a conventional magnetic brush developing device.

In FIG. 1, 1 is a hopper that stores developer, 2 is a magnet roll, and 3 is a latent image carrier. Conventionally, this type of magnetic brush developing device has a latent image carrier 3 brought close to a magnet roll 2 equipped with a hopper 1 for storing developer, and the latent image carrier 3 is brought into contact with the developer supplied from the hopper 1. The structure is such that development is performed by At development point A in FIG. 1, if the electrostatic force from the electrostatic latent image on the latent image carrier 3 applied to the developer is stronger than the magnetic force from the magnet roll 2, the developer will adhere to the latent image. Be visualized.

In the configuration shown in FIG. 1, it is extremely difficult to control the electrostatic force and magnetic force applied to the developer, and to control the strength of the sliding contact of the magnetic brush that brings the developer into contact with the latent image carrier 3.

Specifically, the distance between the latent image carrier 3 and the magnet roll 2 at the development point A, the thickness of the magnetic brush formed with developer on the sleeve of the magnet roll 2, and the latent image carrier 3
The main controlling factors are the time during which the latent image carrier 3 contacts the developer (development time), the relative speed between the latent image carrier 3 and the magnetic brush, that is, the conveyance speed of the latent image carrier 3 and the rotation speed of the magnet roll. The smaller the distance between the latent image carrier 3 and the magnet roll 2, the thicker the magnetic brush, the longer the development time, and the higher the rotation speed of the magnetotrol 2, the better the developing characteristics will be. It is something that can be done.

However, in the conventional magnetic brush developing device, when the operation starts, the developer accumulated in the contact portion B between the latent image carrier 3 and the magnetic brush containing the developer obstructs the movement of the latent image carrier 3. In order to prevent this, conventional methods have been to use mechanical or magnetic force to circulate the developer accumulated in the contact area B to the hopper, or to periodically close the gap between the magnet roll 2 and the latent image carrier 3. It was necessary to use a special method such as spreading the developer and flowing it away in the direction of arrow A.

OBJECT OF THE INVENTION The present invention eliminates the drawbacks of the above-mentioned conventional examples, and while satisfying the conditions for obtaining good development characteristics, does not require the complicated method of the above-mentioned conventional structure, but reliably and inexpensively. The object of the present invention is to provide a magnetic brush developing device that can achieve the above object.

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention rotates a cylindrical sleeve made of a non-magnetic material and a magnet roller having a plurality of magnetic poles provided inside the sleeve. A magnetic developer is supplied onto the sleeve to form a magnetic brush on the sleeve surface, and a roller having a plurality of protrusions formed on the cylindrical surface that guides the latent image carrier to the vicinity of the sleeve is provided. By arranging it facing the sleeve, the latent image can be visualized uniformly.

DESCRIPTION OF EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, 11 is a hopper that stores the developer 12, and 13 is a magnet roller consisting of a fixed sleeve 14 made of a non-magnetic material and a rotatable magnet roll 16 having a large number of magnetic poles housed within the sleeve 14. , 16 is a latent image carrier, 17 is an introduction guide that conveys the reservoir portion carrier 16 to the development point A, and 18 is an opposing guide roller that faces the magnet roller 13 and forms a development gap a at the development point A.
19 indicates the amount of developer supplied from the hopper 11 by 1ff.
It is a doctor blade that does both l and j.

Next, the operation of the above embodiment will be explained. When the magnet roll 15 of the magnet roller 13 rotates, the developer on the fixed sleeve 14 forms a magnetic brush of the developer due to its magnetic force, and the developer rotates on the fixed sleeve 14 as the magnet roll 15 rotates. It moves in the opposite direction to the direction (indicated by arrows in Figure 2). Therefore, magnet roll 1
The magnet roller 1 is moved from the homper 11 by 50 rotations.
A developer is supplied onto the stationary sleeve 14, forming a magnetic brush on the stationary sleeve 14, and moves to the development point A.

In this case, the amount of developer sent out from the hopper 11 is determined by the gap b between the doctor blade 19 and the fixed sleeve 14.
(Doctor Blade Gap)
The width of this gap b is the width of the latent image carrier 16 at the development point A.
must be determined to ensure that it comes in contact with the developer.

In this embodiment, the gap b is made larger than the development gap a. At the development point A, an opposing guide roller 18 is provided opposite the magnet roller 13 in order to form a development gap a. 1
It has a structure in which it is guided to be located at a predetermined distance from 3. When the latent image carrier 16 on which the electrostatic latent image has been formed is conveyed by the introduction guide 17 and comes into contact with the developer, the developer is charged with the opposite polarity to that of the latent image, so the developer is applied to the latent image area. It is attached and visualized.

By the way, the doctor blade 19 and the magnet roller 1
3 is larger than the development gap a formed by the opposing guide roller 18 and the magnet roller 13 due to developer supply conditions. The amount of developer supplied from the pumper 11 becomes larger than the amount of developer supplied, and the developer gradually accumulates in a portion B in front of the development point A.

In this embodiment, as shown in FIG.
The cylindrical surface of No. 8 is grooved with a plurality of protrusions, and since the developer can pass through the recess 20 of the cylindrical surface, it is possible to prevent the developer from staying in the B section. . Furthermore, at the development point A, the positional relationship between the magnet roller 13 and the latent image carrier 16 is maintained by the convex portion 21 on the cylindrical surface of the opposing guide roller 18, so that development characteristics equal to the development gap a can be obtained. .

Effects of the Invention The present invention has the above-mentioned configuration, and includes a developing gap a, a doctor blade gap b, and a magnet roller 13.
The design specifications that directly affect the development characteristics, such as the rotation speed of the
This can be determined from the viewpoint of development characteristics without being restricted by the factor of retention of developer in portion B shown in the figure. In addition, it is possible to eliminate problems caused by developer retention such as scattering of developer and failure of the latent image carrier to run in the developing section, which is a major advantage in improving the uniformity of quality and reliability of the device. has.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional magnetic brush developing device, FIG. 2 is a side sectional view of a magnetic brush developing device according to an embodiment of the present invention, and FIG. 3 is a developing section used in the magnetic brush developing device of the present invention. FIG. 3 is a plan view showing the arrangement of rollers in FIG. 11...hopper, 12.river...developing section, 13
...Instep magnet roller, 14...Fixed sleeve, 16...Magnet roll, 16...
Latent image carrier, 1a...Introduction guide, 18...
...Opposing guide roller, 19...Doctor blade. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
figure

Claims (1)

[Scope of Claims] A cylindrical sleeve made of a non-magnetic material, a magnet roller having a plurality of magnetic poles provided in the sleeve, and a plurality of protrusions arranged on the cylindrical surface and facing the sleeve. A magnetic brush developing device comprising a cylindrical roller formed with a cylindrical roller. −