JPH0435076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device using magnetic one-component toner, and particularly to a developing device that can prevent leakage of toner to the outside of a developing container.

[Prior art]

In the developing device of a copying machine, toner, which is a lightweight fine particle, is adsorbed to the developing roll provided in the developing container, so the toner is easily scattered from the developing roll as the developing roll rotates. floating inside the developer container. Then, this floating toner leaks out from the gap between the photoreceptor and the developer container and stains the inside of the machine, so a means for preventing this is required.

For this reason, conventionally, for example, a developing device using a magnetic one-component toner has been proposed which is equipped with a toner leak prevention means as shown in FIG. That is, in a developer container 2 that is provided close to the photoreceptor 1 and is open on the photoreceptor 1 side, a magnet 3 is attached to the outer wall surface of the developer container 2 along the opening edge of the developer container 2. The floating toner flowing outward from the gap between the developer container 2 and the photoreceptor 1 is attracted to the magnetic polarity 3a of the magnet 3 and its vicinity, thereby preventing toner from leaking to the outside of the developer container 2. It is.

However, since this type of device is configured to attract floating toner, if it is used for a long time, a large number of toners will be attracted to the magnetic pole portion 3a and its vicinity, resulting in a decrease in the suction force.
Of the toner floating toward the gap between the developer container 2 and the photoreceptor 1, only the toner in the vicinity of the magnetic pole portion 3a can be attracted, and the remaining toner leaks outside, causing a problem.

[Purpose of the invention]

The present invention aims to eliminate the above-mentioned problems in the conventional developing device of a copying machine. More specifically, by utilizing magnetic repulsion, the leakage of floating toner to the outside of the developing container is prevented. It is an object of the present invention to provide a developing device for a copying machine that can effectively prevent ejection for a long period of time.

[Structure of the invention]

That is, the present invention provides a developing device for a copying machine in which a developing roll housed in a developing container is opposed to a photoreceptor through an opening provided in the developing container, and development is performed using a magnetic one-component toner. A shielding means consisting of a plurality of magnets having similar poles arranged close to each other is provided at the edge of the opening of the developer container, and the shielding means is provided in the gap between the developer container and the photoreceptor. A magnetic shield (hereinafter referred to as a magnetic curtain) is formed by a repelling magnetic field, thereby sealing off the floating toner in the developer container with the magnetic curtain and preventing leakage to the outside of the developer container. It is something to do.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device for a copying machine according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 shows a developing device of a copying machine to which the present invention is applied. The developing roller 7 is composed of a developing roll 7 facing the photoreceptor 5 through the opening 6a, and a shielding means 8 provided at the edge of the opening of the developing container 6.

The developing roll 7 is composed of a sleeve (not shown) whose outer peripheral surface rotates in a direction opposite to that of the photoreceptor 5, and a plurality of magnets (not shown) fixed inside the sleeve. Toner is magnetically attracted thereon to form a toner layer 7a.

The developer container 6 is made of a non-magnetic material such as aluminum or plastic, and the inner wall above the developer roll 7 is provided with the toner layer 7a.
A trimmer 9 is provided to regulate the thickness to a predetermined thickness.

The shielding means 8 is composed of a plurality of magnets with similar poles arranged close to each other along the opening edge of the developer container 6. Inner magnet 1 on the outer wall surface
The structure is such that the outer magnet 0a and the outer magnet 10b are attached with their poles aligned. Therefore, a magnetic curtain (not shown) is formed in the gap A between the developer container 6 and the photoreceptor 5 by the repelling magnetic fields of the north poles.

The shielding means 8 may also be a magnet as shown in FIG. 4, for example, a bipolar magnet 11 in which the magnetic poles on the opening side of the developer container 6 are of the same type and have a bipolar structure. It is.

Further, the magnet used in the shielding means 8 of the present invention may be one that can obtain a predetermined effect.
Either a permanent magnet or an electromagnet can be used, and there is no particular limitation.

Therefore, according to this embodiment, even if the toner scatters from the rotating developing roll 7 during development and becomes floating toner and moves toward the gap A between the developing container 6 and the photoreceptor 5, the shielding means 8 prevents this gap. A magnetic curtain (not shown) is formed at A to magnetically suspend toner 12.
Since the floating toner 12 is sealed off, the floating toner 12 is repelled by the magnetic curtain and does not leak out of the developer container 6.

Furthermore, even if development is carried out over a long period of time, the floating toner 12 does not adhere to the magnetic pole portion of the magnet constituting the shielding means 8 that faces the photoreceptor 5 and its vicinity, so that the toner is effectively removed. Leakage can be prevented.

〔Effect of the invention〕

Since the present invention has the above configuration,
Toner leakage can be prevented for a long period of time, and staining caused by toner inside the copying machine can be reliably prevented, and the effects are tremendous.

Further, since the present invention utilizes magnetic repulsion, toner is not attracted to the shield means, and maintenance management is easy.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a toner leak prevention means in a developing device of a conventionally used copying machine;
FIG. 2 is a schematic sectional view of a developing device of a copying machine to which the present invention is applied, FIG. 3 is an enlarged sectional view of the main part of FIG. 2, and FIG. 4 is a modification of the shielding means according to the present invention. It is a schematic sectional view showing an example. Explanation of symbols, 1, 5... photoreceptor, 2, 6... developing container, 3... magnet, 7... developing roll, 8... shielding means, 10a, 10b... inner magnet, outer magnet, 11... Bipolar magnet, 12...Floating toner, A
……gap.

Claims (1)

[Claims] 1. In a developing device that performs development using a magnetic one-component toner by arranging a developing roll housed in the developing container to face a photoreceptor through an opening provided in the developing container, the opening edge of the developing container 1. A developing device for a copying machine, characterized in that a shielding means is provided in the section, the shielding means consisting of a plurality of magnets having the same kind of poles arranged close to each other.