JPS60126674A - Developing device - Google Patents

Abstract

PURPOSE:To prevent swelling of a developer generated in both end parts of a regulating plate and leaking-out and scattering to the outside, by providing a member formed by a magnetic material, on both end parts of a developer layer thickness control means. CONSTITUTION:A magnetic tuft formed on the circumferential surface of a sleeve 3 is held on the circumferential surface of the sleeve 3 by a magnetic force of a magnetic roll 4 provided on the sleeve 3 and carried to a gap area of a regulating plate 7. In this gap area, a line of magnetic force from a magnetic pole of the roll 4 leads and magnetizes a magnetic material piece 12 provided on both end parts of the plate 7. The magnetic pole of the roll 4 becomes an opposite polarity successively by a rotation of the roll, and the polarity by which the magnetic material piece 12 is induced and magnetized is also varied. Accordingly, a magnetic developer D carried onto the sleeve 3 is regulated to a fixed thickness when it passes through a tip surface 7A of the plate 7, and on the other hand, the magnetic developer passing through a tip surface 12A of each magnetic material piece 12 comes not to advance easily through a gap S2 of the magnetic material piece 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device used in an electrostatic recording device. The present invention relates to a developing device improved to prevent leakage to the outside.

In a developing device that uses a magnetic powder developer, such as a developing device of a dry-type electrophotographic copying machine, a thin developer is placed on the outer periphery of a developer conveying member (developing sleeve) that has a magnet inside. A layer is formed, and this developer layer is conveyed to a development area to develop an electrostatic latent image formed on an electrostatic image carrier (photosensitive drum).

In particular, when developing with a -component magnetic toner or a two-component developer using a microcarrier, etc., there is a spike regulating plate that regulates the thickness of the developer layer, and a spike regulating plate that closely opposes the regulating plate to control the magnetic developer. It is necessary to maintain a very small gap of approximately 0.2 to 1.0 cm between the developing sleeve and the generally non-magnetic developing sleeve.

Since this gap is minute, the developer passing through this gap may contain small aggregates, foreign matter such as paper powder, etc.
If dust, lint, etc. are present, they will clog the gap between the regulating plate and the developing sleeve, causing so-called clogging, and this clogging will impede the conveyance of the developer. There will be areas where there is no developer or areas where the developer is thin compared to other areas, so if you develop in this state, you will end up with so-called white streaks, which are lines that appear white or thin in those areas on the image. However, there was a drawback in that the copy quality was significantly impaired.

In addition, it is not easy to remove developer aggregates caused by clogging caused by dust (the work to restore them is troublesome and maintenance is complicated).

FIG. 1 is a diagram showing a schematic configuration of a conventional developing device known as a magnetic brush developing device.

In the figure, l indicates an electrostatic image carrier (hereinafter referred to as an image carrier) that rotates clockwise, such as a photosensitive drum. The developing device 2 includes a non-magnetic developer carrier (hereinafter referred to as a sleeve) 3 that is rotationally driven in a counterclockwise direction and a magnetic roll 4 that rotates clockwise around a rotating shaft 50 inside the sleeve 3. A developing roll and the sleeve containing a developer.

a hopper 6 for supplying developer to the sleeve 30;
A spike regulation plate (hereinafter referred to as regulation plate) made of a magnetic material that mechanically regulates the height of the magnetic spikes of the developer layer formed on the surface.
It is equipped with 7.

The magnetic roll 4 consists of a plurality of developing magnetic poles in which north and south poles are arranged alternately. Of course, the magnetic roll 4 and the sleeve 3
The magnetic roll 4 may be fixed to the main body of the copying machine and only the sleeve 3 may be rotated counterclockwise. Alternatively, the sleeve 3 may be fixed and only the magnetic roll 4 may be rotated clockwise. - In component development, a method in which at least the magnetic roll 4 rotates among the above-mentioned methods is preferable. That is, when the magnet is rotated, the magnetic poles rotate alternately and approach the tip of the regulating plate 7, causing the developer to be slightly vibrated, making it difficult for foreign matter to clog the gap near the regulating plate 7. .

Although the bias power supply 8 applied to the sleeve 3 is shown in FIG. 1, it may be grounded as appropriate depending on the type of photoreceptor (polarity of the electrostatic latent image), the magnetic developer used, etc. good.

Now, when the sleeve 3 rotates, the developer is attracted to the surface of the sleeve 30 and fed by the magnetic action of the internal magnetic roll 4, but the developer layer is regulated to a constant thickness by the spike regulating plate 7. Thereafter, the developer is further conveyed by the sleeve 3 and reaches a development area where the sleeve 3 faces the image carrier 1, where the developer damps the vibrations on the surface of the image carrier 1.

When an electrostatic latent image is formed on the image carrier l, the toner in the developer is attracted to the electrostatic latent image by electrostatic attraction force, and the electrostatic latent image becomes a visible image.

By the way, the developer used in this type of developing device includes:
Magnetic powder (carrier) such as iron powder and colored synthetic resin powder (
There are two-component developers, which consist of a toner), and one-component developers, which are synthetic resins mixed with a colorant and magnetic powder.Recently, the latter has begun to attract attention because of its maintenance-free nature.

- A component type developer does not contain a carrier and therefore consists only of particles having a smaller particle size than a two-component type developer.

Therefore, the distance between the regulating plate 7 and the sleeve 3 is selected to be 0.5 sm or less, which is conveniently smaller than about 1 to 5 ms in the case of a two-component developer. For this reason, -component type developers have a tendency to clump by nature and are even more likely to clump due to the pressure applied at the narrow regulating section.As the gap between the developing sleeve and the regulating plate is narrow, even the slightest amount of agglomeration or dust can cause eyelids. There is a problem in that clogging occurs, resulting in uneven density in the vertical direction. If a lump of developer or dust is mixed in, it will clog between the regulating plate 7 and the sleeve 3, and the developer will not be conveyed to that area, and development will not be performed (white vertical lines will appear on the copy). ) problems are likely to occur. A phenomenon in which the developer sticks to the sleeve also occurs. These phenomena are more likely to occur when an insulating toner is used as a developer.

As a result of experiments and studies, it has become clear that one of the causes of such aggregated toner and dust generation is from the vicinity of the side member that holds the developer and the developing roller.

FIG. 2 is an example of a sectional view showing a developing roll of a conventional developing device and a side member of the developing device. In the figure, developer particles tend to accumulate at the end of the developing roller during development due to the spike control plate, magnetic roll, etc.

Therefore, in order to prevent the developer from leaking out between the side member 10 and the developing sleeve 3, a sponge-like elastic member 11 is stuffed into the recess of the side member 100 and fixed.
By making strong sliding contact with the outer periphery of the end of the sleeve 3, toner leakage is prevented. However, in such a configuration, a portion of the sliding surface of the elastic member 11 falls off due to friction caused by the rotation of the IJ-pull 3, and is mixed into the developer as dust. Alternatively, the developer particles that have entered and become clogged between the sliding contact surfaces 3 and 11 aggregate, and the coagulated mass mixes into the developer in the developer container. Fragments of these elastic members, developer coagulation, and the like are considered to be the main causes of the above-mentioned development failure.

Furthermore, if the developer sludge, fallen lumps, coagulated lumps, etc. enter the shaft end of the developing roller through the gap between the side member IO and the sleeve 3, they may enter the bearings, gaps, etc., and cause the rotation of the developing roller to deteriorate. The developer may leak outside and scatter, causing adverse effects. As mentioned above, the sponge-like elastic member is insufficient and unsatisfactory as a means for preventing developer leakage.

Other conventional techniques include forming both ends of the regulating plate into a special shape, providing a groove at the end of the sleeve, providing a member with a special shape made of non-magnetic material, and making the magnetic roller longer than the length of the regulating plate. Efforts have been made to make the sleeve longer and to make the surface roughness of the sleeve different between the inside of the image forming area and the outside of the image at both ends. However, these have disadvantages in that they have a complicated shape and are difficult to process, the cost of the developing device is high, and the developing conditions are unstable.

The specification of Japanese Patent Publication No. 56-25670 attempts to solve the above problem and proposes the use of a magnetic spike regulating plate. According to the above proposal, it takes a lot of effort to provide the same magnetic developer layer thickness.

Since the distance between the sheets can be widened, it is possible to prevent clogging at the cutting section due to aggregates of magnetic developer, paper dust, etc., and it is possible to form a thin developer layer.

Although the above proposal has the above-mentioned features, since the spike regulating plate made of a magnetic material and the sleeve surface maintain a uniform distance, developer bulges occur at both ends of the sleeve. , it is inevitable that this developer leaks out from both ends.

[Purpose of the invention]

The present invention improves the above-mentioned drawbacks, and the both ends of the ear standing regulation plate,
It is an object of the present invention to provide a developing device that prevents the developer from bulging up and further prevents the developer from leaking and scattering from both ends to the outside.

[Structure of the invention]

The present invention aims to achieve the above-mentioned object, and consists of a developer support means provided opposite to an electrostatic image bearing means for supporting and conveying developer to a developing area, and a developer support means for supplying developer onto the developer support means. A developing device having a means for regulating the layer thickness of the developer, characterized in that members made of a magnetic material are disposed at both ends of the developer layer thickness regulating means. be done.

〔Example〕

Hereinafter, the present invention will be explained by showing specific examples thereof.

FIG. 3 shows a side sectional view of the developing device of the present invention, and FIG. 4 is a perspective view of the main parts thereof. In these figures, the same structural parts as in FIGS. 1 and 2 are designated by the same reference numerals 41 as in the previous figure.

The regulating plate 7 made of a non-magnetic material is attached to the side member 1 of the developing device 2.
0, and its tip 7A maintains a gap of Ns+, for example 0.2 to 0.4 m, between the surface of the sleeve 3 and the surface of the sleeve 3 for a predetermined distance to maintain the developer layer in order to obtain optimal development conditions. It is fixed evenly. A magnetic piece 12 is fixed to both ends of the regulating plate 70 with a tightening member 3 such as a rivet and screw, and a predetermined gap S1, e.g. A distance of .1 to 0.2 degrees is maintained.

The magnetic piece 12 is suitably made of, for example, a magnetic stainless steel plate.

Next, the operation of the developing device according to the present invention will be described. Due to the magnetic force of the magnetic roll 4 provided on the sleeve 3 , the magnetic ears (magnetic brush) formed on the circumferential surface of the sleeve 30 are held on the circumferential surface of the sleeve 30 and conveyed to the gap region of the regulating plate 7 . In this gap region, the lines of magnetic force from the magnetic poles of the magnetic roll 4 are transmitted to the magnetic pieces 1 fixed to both ends of the regulating plate 7.
2 is induced magnetized. Since the magnetic roll 4 is rotating,
The magnetic pole of the magnetic roll 4 becomes reverse polarity sequentially, and the magnetic material piece 1
The polarity with which 2 is induced magnetized also changes accordingly. Therefore, the magnetic developer conveyed onto the sleeve 3 is regulated to a constant thickness when passing through the tip surface 7A of the non-magnetic regulating plate 7, but the thickness of the magnetic developer is regulated to a constant thickness when passing through the tip surface 7A of the non-magnetic regulating plate 7. The magnetic developer passing through 12A is difficult to advance through the gap S between the magnetic pieces 12 because the lines of magnetic force are in the direction perpendicularly crossing the sleeve 3. This is because the magnetic field existing between the magnetic roll 4 and the magnetic piece 12 acts on the developer as a force to prevent the magnetic developer from flowing out of the hopper 6.

Note that this suppressing force can be applied by changing the distance of the magnetic material piece 12 from the magnetic roll 4, thereby changing the strength of the magnetic field. It can be freely controlled independently of the

FIG. 5 is a side view showing another shape of the magnetic powder piece according to the present invention. The magnetic piece 14 is a U-shaped or IXL-shaped magnetic plate.
It is formed into a letter shape, etc., and is secured to both ends of the regulating plate 7 with tightening members 15, respectively. The magnetic piece 14 may be attached by utilizing its own spring properties or by adhesion.

Due to the magnetic suppression force of the magnetic material pieces 14, there is no build-up of developer at both ends of the sleeve 30, there is no leakage or scattering of developer from both ends, and there is no possibility of uneven density or magnetism near both ends. This also eliminates problems such as the ears collapsing and clumping into flakes. Although the embodiment of the present invention has been described using a magnetic piece, a magnetic force generating device using an electromagnet may be provided.

Furthermore, since the magnetic piece according to the present invention is separate from the regulating plate, it is easy to replace the magnetic piece 12 or 14 with one of a different width. When manufacturing a model with specifications in which the width of the magnetized area on the sleeve 3 is changed and the width of one image area is changed, it is possible to do this by simply replacing the magnetic piece without changing the magnetic roll 4. Become.

〔Effect of the invention〕

According to the present invention, in order to adjust the regulating plate to a uniform desired developer layer thickness and always maintain optimum development conditions, there is no K, and there is no need to prevent leakage of developer from both ends of the regulating plate, crushing of the magnetic ear, and the like. This eliminates density unevenness caused by the increased thickness of the developed layer in the area, and significantly reduces the shape and dimensional accuracy of the area facing the sleeve, as well as the accuracy of the attachment to the sleeve, compared to the conventional example described above.・Very advantageous in terms of assembly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a typical one-component electrophotographic developing device, and FIG. 2 is a side sectional view of its developing roll. FIG. 3 shows a side sectional view of the developing device according to the present invention;
The figure is a perspective view of the main part. FIG. 5 is a side view showing another embodiment of the magnetic piece and regulating plate according to the present invention. 2...Developing device 3...Sleeve 4...Magnetic roll 7...Regulation plate 12, 14...Magnetic material piece 13, 15...Tightening member Yoshimi Kuwabara Figure 1

Claims (1)

[Claims] The developer support means is provided opposite to the electrostatic image bearing means and supports the developer and conveys it to the development area, and means for regulating the layer thickness of the developer supplied onto the developer support means. A developing device characterized in that magnetism generating means are disposed at both ends of the developer layer thickness regulating means.