JPH0447830B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device that develops an electrostatic latent image formed on an electrostatic image carrier using a magnetic developer.

[Prior Art] In a developing device using a magnetic powder developer, for example, a developing device of an electrophotographic copying machine using a dry developing method, a thin developer layer is formed on a developer conveying member (developing sleeve), and this developer is The layer is conveyed to a development area to develop an electrostatic latent image formed on an electrostatic image carrier (for example, a photoreceptor drum).

In particular, when developing using a two-component developer such as one-component magnetic toner or a microcarrier, a spike regulating plate that regulates the thickness of the developer layer;
The distance between the regulating plate and the generally non-magnetic developing sleeve which faces the magnetic developer and carries the magnetic developer is approximately 0.2.
It is necessary to maintain it within a minute distance of ~1.0mm.

Since the gap between the two is minute, if there are small aggregates or foreign matter such as paper dust, dust, thread, etc. in the developer passing through the gap, the regulation plate and the developing sleeve may This causes a so-called clogging, and the transport of the developer is obstructed at the clogged area. Therefore, if development is performed in this state, a so-called white streak, which is a line-shaped white spot or thinning in that part, will occur on the image, which will significantly impair copy quality.

Further, it is not easy to remove developer aggregates and the like due to clogging once generated, and the work to restore it is troublesome and maintenance is complicated.

In order to solve the above-mentioned drawbacks, conventional methods have been taken such as providing a foreign matter removing member or making the height of the magnetic ears of the developer uniform up to the developing position.

As an example, Japanese Patent Application Laid-Open No. 53-63022 proposes making the height of the magnetic ears of the developer uniform up to the development position. However, this proposal has the following problems, which have not yet been fully resolved.

(1) It is difficult to make the developer uniform if the time it takes for the developer to travel between the spike control section and the development position is short.

(2) The magnetic pole plate essentially becomes a second spike control plate,
Foreign matter stuck in this magnetic pole plate causes a similar problem.

(3) The setting of the magnetic pole plate is delicate; if it is too far away, it will have no effect at all, and if it is too close, it will promote unevenness in the developer layer.

(4) The white streaks occur even when the magnetic poles rotate.
As another measure to prevent clogging, Japanese Patent Laid-Open No.
No. 57-116373 has been proposed. According to this method, foreign matter in the developer is combed out after development, but the trapping effect is insufficient, and furthermore, it cannot fundamentally solve clogging of foreign matter caused by contamination in other parts. In particular, the developer refluxed from the cleaning device and put into the developing device contains a large amount of foreign matter such as paper dust, and the above proposal is completely ineffective.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problem, and has a narrow space between a spike regulating plate that regulates the thickness of the developer layer and a developing sleeve that conveys the developer.
By completely removing the uneven thickness of the developer layer caused by foreign matter stuck in the developer layer before it reaches the development area, and forming a uniform developer layer, high and stable copy quality can be maintained. The object of the present invention is to provide a developing device.

[Structure of the invention]

The object of the present invention is to provide: a hopper for storing and supplying a developer; a rotary sleeve within the hopper partially facing an electrostatic image carrier; and a rotatable sleeve rotatably built in the rotary sleeve. a magnetic roll that rotates in a direction opposite to the rotating sleeve; a regulating member that regulates the supply amount of the developer when the rotating sleeve supplies the developer to the development area on the surface of the electrostatic image carrier; a cover made of a non-magnetic material that is provided between the development areas on the image carrier surface and guides the developer to the development area; and a plurality of covers provided on the outer surface of the cover in a diagonal direction with respect to the direction in which the developer is guided. a magnet with a magnetic field;
This is achieved by a developing device characterized by having the following structure.

[Effect]

According to the present invention, even if the thickness of the developer conveyed onto the developing sleeve is uneven due to foreign matter stuck in the narrow gap between the spike control plate and the developing sleeve, the developer layer is uniform. By causing the developer to rise under the action of the converting member, a developer layer having a completely uniform thickness is formed before reaching the development area,
The purpose is to provide high-quality copies without white streaks or uneven images.

〔Example〕

The present invention will be explained in detail below. FIG. 1 shows a schematic configuration of an example of a developing device embodying the present invention.

In FIG. 1, reference numeral 1 denotes an electrostatic image carrier (hereinafter referred to as an image carrier) that rotates in a clockwise direction, such as a photosensitive drum. The developing device 2 includes a non-magnetic developer carrier (hereinafter referred to as a sleeve) 3 which is rotationally driven in a counterclockwise direction, and a mag roll, for example, which rotates clockwise around a rotating shaft 5 inside the sleeve 3. A hopper 6 that accommodates a developer and supplies the developer to the sleeve 3, and a hopper that mechanically regulates the height of the magnetic ear of the developer layer formed on the circumferential surface of the sleeve 3. A standing regulation plate (hereinafter referred to as regulation plate) 7 and the sleeve 3
A developer layer equalizing member 8 (hereinafter referred to as a equalizing member) is provided between the regulating plate 7 and the developing area A in a direction of rotation of the sleeve 3 and facing the surface of the sleeve 3. There is. Furthermore, the equalizing member 8
is composed of a non-magnetic cover 8A facing the circumferential surface of the sleeve 3 and a magnet 8M. cover 8
A is not a ferromagnetic material, but is non-magnetic or paramagnetic, and is made of, for example, synthetic resin or metal such as brass or aluminum. The magnet 8M is a fixed magnet provided on the opposite side of the cover 8A facing the sleeve 3, and its magnetic pole faces toward the sleeve 3. That is, the lines of magnetic force caused by the magnet 8M reach the circumferential surface of the sleeve 3. Therefore, when the magnetic developer D conveyed onto the non-magnetic sleeve 3 passes through this magnetic field, it is moved by the interaction between the magnetic field of the magnet 8M and the magnetic field of the magnetic roll 4.

The magnetic roll 4 consists of a plurality of developing magnetic poles in which north and south poles are arranged alternately. The magnetic roll 4 and the sleeve 3 rotate relative to each other, and the magnetic roll 4 may be fixed to the main body of the copying machine and only the sleeve 4 may be rotated counterclockwise. Alternatively, the sleeve 4 may be fixed and only the magnetic roll 3 may be rotated counterclockwise. In one-component development, among the above methods, the rotation method using the magnetic roll 4 is most preferable.

Here, the magnetic developer D used in the developing device according to the present invention includes a one-component magnetic toner, a two-component developer consisting of a magnetic carrier and a non-magnetic toner, a two-component developer consisting of a magnetic carrier and a magnetic toner, etc. refers to

The relationship between the distance a between the surface of the sleeve 3 and the tip of the regulating plate 7, and the distance b between the surface of the sleeve 3 and the surface of the equalizing member 8 opposing thereto is such that b>a. Although the equalizing member 8 may be fixed to the developing device 2 or other members, it is preferably fixed to or integrated with the regulating plate 7 in order to correctly maintain the relationship between a and b.

Figures 2a and 2b show other embodiments of the equalizing member 8, with figure a showing a perspective view and figure b showing a developed view. This is made up of diagonally magnetized magnets arranged in parallel. According to this, since the direction of the magnetic field acts obliquely with respect to the rotational direction of the sleeve 3, the magnetic developer conveyed on the sleeve 3 can move in an oblique direction.

Although the bias power supply 9 applied to the sleeve 3 is shown in FIG. 1, it may be changed as appropriate depending on the type of photoreceptor (polarity of the electrostatic latent image), the magnetic developer used, etc.
You may take measures such as grounding.

The operation of the developing device of the present invention constructed as described above will be explained with reference to FIG.

The magnetic developer D in the upper hopper 6 is magnetically held on the circumferential surface of the sleeve 3 and conveyed counterclockwise by the action of the sleeve 3 and the magnetic roll 4 that rotate relative to each other. The height of the magnetic brush (magnetic brush) formed on the circumferential surface of the sleeve 3 is regulated by a regulating plate 7 , and then conveyed to a region facing the equalizing member 8 . The magnetic developer D passing through the area of the equalizing member 8 is disturbed by the interaction between the magnetic field formed by the magnetic roll 4 and the magnetic field formed by the equalizing member 8, and is transported from the regulating plate 7. Due to the pressing force of the subsequent magnetic developer D, it also moves in the lateral direction while passing through the area of the equalizing member 8, thereby making the thickness distribution of the magnetic developer layer on the sleeve 3 uniform. Ru. Therefore, at the time when the developer reaches the development area after passing through the homogenizing member 8, the developer magnetic ears are uniform in the longitudinal direction of the sleeve 3. In this way, the magnetic developer D uniformly distributed on the sleeve reaches the development area and is used to develop the electrostatic latent image on the photoreceptor drum as the electrostatic image carrier 1 moving in the direction of the arrow. Served.

As a result, even if the regulating plate is clogged with foreign matter such as developer coagulation and the magnetic ears are low or there are areas without magnetic ears on the sleeve, while passing through the area of the equalizing member, Since it is made uniform, clogging problems can be avoided and stable images can be obtained.

In the above explanation, the magnetic roll containing the magnetic pole and the sleeve are both rotated, but the developing device in which both rotate relative to each other, for example, either a fixed magnetic pole rotating sleeve type or a magnetic pole rotating sleeve fixed type, can also be used. The uniformizing member of the present invention exhibits an effect, and the effect is particularly remarkable in the double-rotation type magnetic sleeve.

FIG. 3 is a front view and a plan view showing an example of a magnet 38M having a notched groove 38H.

A repulsive magnetic field is formed by these holes or grooves, and the magnet 2 having such a configuration has a magnetic force distribution in the longitudinal direction of the magnet due to the arrangement thereof.
The magnetic developer on the sleeve 3 facing 8M or 38M moves in the transport direction and in a direction perpendicular or diagonal to the transport direction due to the interaction between the magnetic force of the magnet and the magnetic force of the magnetic roll 4, and the developer layer is made uniform. .

It goes without saying that the present invention is not limited to the above embodiments. Note that the equalizing member 8 is the sleeve 3
Since it is only necessary to provide them close to each other almost along the circumferential surface, they do not need to be integrated with the regulating plate 7 or the developing device 2.

Further, by reciprocating the uniformizing member 8 in the longitudinal direction of the sleeve, the effect of uniformizing the developer layer becomes even greater.

〔Effect of the invention〕

As explained above, according to the developing device of the present invention, (1) Even if clogging occurs between the regulating plate and the sleeve due to foreign matter, the portion of the sleeve where there is no developer caused by this clogging will be removed. By the magnetic force of a developer layer uniformizing member having a magnetic force generating member, the magnetic force is completely eliminated and a uniform developer layer is obtained, thereby stably providing high-quality copies without white streaks or density unevenness over a long period of time. Can be done.

(2) Furthermore, since this can be achieved with a simple configuration, an inexpensive developing device can be provided.

(3) Since the developer is mixed while passing through the developer layer homogenizing member, a more homogeneous developer can be obtained, and copies that are stable over a long period of time can be obtained.

(4) Since it passes through the non-magnetic cover 8A configured as the developer layer homogenizing member 8 and the magnet 8M which forms a magnetic field in an oblique direction, the means for passing perpendicularly to the surface of the developer layer homogenizing member at the end Compared to the above, the uniformity of the developer at each stage is rapidly achieved within a short period of time.
Even during high-speed development, uneven development is prevented.

As described above, the developing device according to the present invention has the advantage that a more uniform thin layer of developer can be easily formed on the sleeve at all times and a high-quality and uniform developed image can be obtained compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device according to the present invention, and FIG.
Figures a and b are a perspective view and a developed view showing another embodiment of the developer layer uniformizing member according to the present invention. FIG. 3 shows a modification of the magnetic force generating member used in the present invention. 1... Electrostatic image carrier, 2... Developing device, 3...
Developer carrier, 4...Magnetic roll, 7...Standing regulation plate, 8, 18...Developer layer uniformization member, 8
A, 18A...Cover, 8M, 18M, 38M...
...Magnet, A...Development area, D...Magnetic developer.

Claims (1)

[Claims] 1. A hopper that stores and supplies developer;
Inside the hopper, a rotating sleeve partially facing the electrostatic image carrier; a magnetic roll rotatably built in the rotating sleeve and rotating in the opposite direction to the rotating sleeve; a regulating member that regulates the supply amount when the developer is supplied to the developing area on the surface of the electrostatic image carrier; and a regulating member provided between the regulating member and the developing area on the image carrier surface, the regulating member disposing the developer to the developing area. A developing device comprising: a cover made of a non-magnetic material that guides the developer; and a magnet having a plurality of magnetic fields provided on the outer surface of the cover in an oblique direction with respect to the guiding direction of the developer.