JPS59231564A - Forming device for thin layer of developer - Google Patents

Abstract

PURPOSE:To circulate magnetic particles in a container sufficiently by providing a member which stirs the interface between a base layer of magnetic particles and a developer above it. CONSTITUTION:A stirring means 24 is provided near the boundary surface between the base layer and a nonmagnetic developer layer and closely to the falling point of the nonmagnetic developer, and fitted to a rotation driving shaft 26 fitted to the developer supply container 13 through plural support rods 28. Further, the stirring means 24 has a stirring member 30 extending at right angles to the paper surface and rotates around the driving shaft 26 as shown by an arrow (d). The circulation of magnetic particles in the base layer is accelerated by the rotation of the stirring means 24 and the nonmagnetic developer at the upper part is taken in and supplied to the base layer part, so the nonmagnetic developer is supplied smoothly. Consequently, the magnetic particles are circulated in the container sufficiently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a thin layer of dry developer. Furthermore,
The present invention relates to an apparatus for forming a thin layer of non-magnetic developer.

Conventionally, various apparatuses have been proposed and put into practical use as dry developing systems. However, in any of the developing methods, it is extremely difficult to form a thin layer of dry developer, and for this reason, the developing device has been constructed by forming a relatively thick layer. However, now that improvements in the clarity, resolution, etc. of developed images are required, it is essential to develop a method for forming a thin layer of dry developer and an apparatus therefor.

As a method of forming a thin layer of a conventionally known dry developer, Japanese Patent Application Laid-Open No. 54-43037 has been proposed and has been put into practical use. However, this concerned the formation of a thin layer of magnetic developer. In order to make magnetic developers magnetic, it is necessary to add a magnetic substance to the developer. Because magnetic materials are added internally (magnetic materials are usually black), there are problems such as poor color reproduction.

For this reason, as a method for forming a thin layer of non-magnetic developer, there are methods in which soft bristles such as beaver hair are used as a cylindrical brush and the developer is adhered to the brush, and a method in which the surface is made of fibers such as velvet is used. A method has been proposed in which the developer is coated on the developing roller using a doctor blade or the like.

However, when an elastic blade is used as a doctor blade for the above-mentioned fiber brush, it is possible to regulate the amount of developer, but uniform application is not achieved, and the fibers of the brush are simply rubbed by the fiber brush on the developing roller. Since no triboelectric charge is imparted to the developer present in between, there is a problem in that fogging and the like are likely to occur.

As a new thin layer forming method that is completely different from the conventional method described above, the present applicant et al. formed a magnetic brush made of magnetic particles on the upstream side of the magnetic particle restraining magnetic pole with respect to the moving direction of the surface of the developer holding member. have already proposed a method of forming a thin layer of non-magnetic developer on a developer holding member using this magnetic brush. However, in this developing device, if the magnetic particles are not sufficiently circulated within the container, the tripod will not be sufficiently applied to the developer, resulting in insufficient adhesion of the developer to the sleeve. It was found that the final developed image had a lot of fog. Accordingly, the present invention provides an apparatus for forming a thin layer of non-magnetic developer on a developer holding member using magnetic particles confined within a container, in which the magnetic particles are sufficiently circulated within the container. An object of the present invention is to provide a thin layer forming device.

1. Glazing 1. The apparatus of the present invention includes a developer supply container having an opening, a non-magnetic member for holding developer provided in the opening and movable endlessly inside and outside the container, and a developer-holding member provided inside the holding member. fixed magnetic field generating means provided on the developer supply container;
a base layer containing magnetic particles; a magnetic particle restraining member that is provided outside the developer holding member and restrains the base layer of magnetic particles within the developer supply container together with a fixed magnetic field generating means;
Furthermore, since it has a member that stirs the interface between the base layer and the developer above it, it has the effect of smoothing the circulation of the magnetic particles and ensuring the supply of the developer to the base layer.

1 Cliff l Examples of the present invention will be described below with reference to the drawings. 1st
The figure is an explanatory view of the method and apparatus for forming a thin layer of nonmagnetic developer according to the present invention.

In FIG. 1, 11 is a cylindrical electrophotographic photoreceptor that moves in the direction of the arrow a. A non-magnetic holding member 12 that holds the developer is provided with a gap between the photoconductor 11 and, in this embodiment, the holding member 12 has a cylindrical shape, but it may also have a web shape that moves endlessly. . The same applies to the electrophotographic photoreceptor 11. Along with this movement of the photoreceptor 11, the developer holding member 12 is rotated in the direction indicated by the arrow. A developer supply container 13 is provided to supply developer to the developer holding member 12 .

The developer supply container 13 has an opening near its lower part, and the developer holding member 12 is provided in the opening. Since a portion of the developer holding member is exposed to the outside through the opening, its surface moves from the inside of the developer supply container to the outside, and then returns to the inside.

An enclosure is formed at the lower part of the developer holding container 13 so as to wrap around the lower part of the developer holding member 12 to prevent the developer from leaking to the outside. A fixed magnetic field generating means for generating a fixed magnetic field, that is, a magnet 14 is fixedly provided inside the developer holding member 12 . Since the magnet 14 is fixed, only the developer holding member 12 rotates. This magnet 14 includes a magnetic particle restraining magnetic pole 20 and a transporting magnetic pole 21, which will be described later.
and a sealing magnetic pole 22.

A magnetic blade 15 (magnetic particle restraining member) made of a magnetic material is arranged near the top of the opening of the developer supply container 12 . The developer holding member 1
On the opposite side via 2 is a magnetic particle restraining magnetic pole 2o of the magnet 14.
However, the position of the magnetic particle restraining magnetic pole 20 is the same as that of the magnetic blade 1.
The developer holding member 12 is disposed at an upstream position in the rotational direction of the developer holding member 12 at an angle θ (5 to 50 degrees) shifted from the position facing the developer holding member 5 .

A rear wall plate 13-1 is provided near the bottom of the developer supply container 13, and as described later, this ensures the presence of magnetic particles near the bottom of the developer supply container 13 and improves the circulation of the magnetic particles. Make it.

An iron piece 18 made of a magnetic material is provided on the inner wall of the developer supply container 13 facing the sealing magnetic pole 21, and a magnetic brush formed between these pieces seals the lower part of the container 13 and prevents the circulation of magnetic particles. It also improves. iron piece 18
In addition to metals such as iron, the magnet may be a magnet that faces the sealing magnetic pole 21 in a reverse polarity relationship. These magnetic members may be attached to the wall of the container 13 facing the sealing magnetic pole 21, or a part of the container itself may be made of a magnetic material such as iron, and the wall of the container facing the sealing magnetic pole 21 may be used to hold the developer. Part '12
It may be configured closer to .

24 is a rotary drive shaft 26, a support rod 28, and a stirring member 3
0 and rotates in the direction of arrow d. The operation of this means will be described later.

The base layer 16 is formed by supplying magnetic particles or a mixture containing magnetic particles and a non-magnetic developer to the developer supply container of the apparatus having such a configuration. The mixture forming the base layer preferably contains about 5 to 70% (by weight) of non-magnetic developer based on the magnetic particles, but it may also contain only magnetic particles. The particle size of the magnetic particles is 30-200, preferably 70-200
It is 150 microns. Each magnetic particle may be made of only magnetic material or may be a combination of magnetic material and non-magnetic material. The magnetic particles in the base layer 16 form a magnetic brush due to the magnetic field generated by the magnet 14, and this magnetic brush performs the circulating action described below. Magnetic particle restraining magnetic pole 20 and magnetic blade 15
A magnetic brush is also formed in between, which confines the magnetic particles of the base layer 16 within the developer supply container 13.

By supplying the nonmagnetic developer 1° onto the base layer 16, two layers are formed substantially in the vertical direction, that is, on the outer periphery of the developer holding member 12 and on the outside thereof. The developer layer may be formed by adding a small amount of magnetic particles to this non-magnetic developer, but even in this case, the magnetic particle content of the developer layer is smaller than that of the base layer 16. Silica particles may be externally added to the non-magnetic developer to improve fluidity, and abrasive particles may be externally added to the non-magnetic developer for polishing the photoreceptor 11. The method for forming the two layers is not limited to supplying the two layers in two stages as described above. For example, it is also possible to supply a substantially uniform mixture of magnetic particles and non-magnetic developer for the entire amount of the base layer 16 and developer layer 17. Then, the developer supply container 13 is vibrated to reduce the difference in specific gravity between the magnetic particles and the non-magnetic developer and the magnet 1.
Two layers may be formed using the magnetic field of 4.

Even when a nearly uniform mixture of magnetic particles and non-magnetic developer is supplied without particularly forming two layers,
This is possible as long as it contains a sufficient amount of magnetic particles to form a magnetic brush, but in order to maintain long-term stability of the magnetic brush, it is preferable to use two layers.

When the developer holding member 12 is rotated with the magnetic particles and developer applied in this way, the magnetic particles are caused by the magnetic field and gravity of each magnetic pole, as shown in Figure 2 (for clarity, the magnetic particles are (omitted) performs a circular motion as shown by the dashed arrow. That is, the developer holding member 12
Near the outer surface of the developer supply container 13, the magnetic particles at the bottom of the developer supply container 13 rise along the outer periphery of the developer holding member 12 due to the interaction between the magnetic field from the magnet 14 and the rotation of the developer holding member 12, and at this time, The magnetic developer and the surface of the developer holding member 12 come into contact, and the non-magnetic developer in the base layer is electrostatically applied onto the developer holding member 12.

In this embodiment, the non-magnetic developer is charged by friction with the magnetic particles or the developer holding member 12, but preferably there is an oxide film on the surface of the magnetic particles or an oxide film at the same electrostatic level as the non-magnetic developer. The developer holding member 1 is insulated with resin, etc., to reduce triboelectricity from magnetic particles, and to remove the necessary charge from the developer holding member 1.
2, it is possible to prevent the influence of deterioration of the magnetic particles (i) and stabilize the application of the developer to the developer holding member 12.

The magnetic particles rise as the developer holding member 12 rotates, but due to the magnetic field formed between the magnetic blade 15 and the magnetic particle restraining magnetic pole 20, the gap between the surface of the developer holding member 12 and the tip of the magnetic blade 15 is reduced. be prevented from passing through. Therefore, the magnetic particles in this part are pushed by the magnetic particles sent one after another, rotate and turn around as shown by the arrows in FIG. 1, and then slowly fall due to gravity. During this falling, the non-magnetic developer at the lower part of the developer layer 17 is taken in and returned to the lower part of the developer supply container 13, and this process is repeated.

On the other hand, since the triboelectrically charged developer is non-magnetic, it can pass through without being restrained by the magnetic field that exists in the gap between the tip of the magnetic blade 15 and the surface of the developer holding member 12, and is developed by the magnetic brush section formed on the magnetic blade section. The surface of the developer holding member 12 is coated uniformly and thinly with the action of mirror force, and the developer supply container 13 that rests on the surface of the developer holding member 12 comes out and faces the surface of the photoreceptor 11 for development. be done.

Since the magnetic blade 15 is tilted upward toward the developer supply container 13, the magnetic particles in the vicinity of the magnetic blade 15 move according to gravity, and therefore, the magnetic particles fall smoothly here. . Furthermore, by tilting the magnetic brush in this manner, the pressure exerted by the non-magnetic developer particles on the upper part of the magnetic brush on the magnetic brush near the magnetic blade 15 is alleviated, and since the height of the magnetic brush is small, the pressure caused by the magnetic particles is reduced. The magnetic particles are also small and prevent the magnetic particles from passing through the gap between the magnetic blade 15 and the developer holding member 12. f? ! The larger the value of v', the better the circulation, and the better the effect of preventing leakage of magnetic particles.

The rear wall plate 13-1 is provided as shown in FIG. 1, and the horizontal distance between the surface of the developer holding member 12 and the inner surface of the rear wall plate 13-1 is adjusted from the upstream side to the downstream side in the rotational direction of the developer holding member 12. The magnetic particles in the sealing portion increase in size as they go (from the bottom to the top in the drawing), that is, in this embodiment, the rear wall plate 13-1 is inclined in the same direction as the magnetic blade 15 of the present invention. This ensures that the developer layer does not come into direct contact with the developer holding member 12 even during long-term operation, and the sealing at the seal portion is also ensured.

As shown in FIG. 2, a stirring means 24 is provided near the interface between the base layer and the non-magnetic developer layer, near the point where the non-magnetic developer falls, and this stirring means 24 is attached to the developer supply container 13. The rotary drive shaft 2'B has a rotary drive shaft 26 and a stirring member 30 that is attached to the rotary drive shaft 2'B by a plurality of support rods 28 and extends in a direction perpendicular to the plane of FIG.
The stirring member 30 is rotated about 26 in the direction of arrow d by a driving means (not shown). Since the stirring member 30 extends to the vicinity of both ends of the developer supply container 13, sufficient stirring is performed even at these ends. The rotation of the stirring means 24 promotes the circulation of the magnetic particles in the base layer and also takes in the non-magnetic developer at the top and supplies it to the base layer, so that the non-magnetic developer is reliably supplied. The stirring means 24 and the developer holding member 12 are separated by at least 4 mm, preferably about 10 mm. If the two are closer than this, the developer holding member 1
2, an excessive amount of non-magnetic developer is supplied to the non-magnetic developer, and the tripo is insufficiently applied to the non-magnetic developer, resulting in fogging in the developed image.

FIG. 3 shows a case where the stirring means 24 is arranged so that it does not come into contact with the magnetic particles of the base layer at all. That is, the stirring member 30 does not come into contact with magnetic particles over the entire rotation range of the stirring member 30, and is completely surrounded by the non-magnetic developer. In this case, the effect of promoting the circulation of the magnetic particles and the effect of taking in the non-magnetic developer are small, resulting in a decrease in density particularly at the edges.

On the other hand, as shown in FIG. 4, when the stirring means 24 is placed completely within the base layer, for example, when magnetic particles coated with fluorocarbon resin are used as the magnetic particles, the circulation of the magnetic particles is easy and non-intrusive. Insufficient supply of magnetic developer. Therefore, problems such as a decrease in image density and self-cutting occur. Therefore, as shown in FIG. 2, it is desirable to place the stirring means 24 at the interface between the non-magnetic developer and the base layer of magnetic particles.

The rotational speed of the stirring means 240 is preferably 2:1 to 1:100 with respect to the rotational speed of the developer holding member, and preferably,
In this example, the rotation speed of the developer holding member was set to 1/2 rotations/second to 1 rotation/second, and a stable result with no fogging or white spots was obtained. The image has been changed.

In the above embodiment, the stirring means 24 was arranged at the bottom of the developer supply container, but it may also be arranged near the magnetic blade 15. FIG. 5 shows such an example. Since the constituent elements are the same as those in the previous embodiment, detailed description will be omitted by assigning the same reference numerals to corresponding elements.

The stirring member 30 is arranged so as to have a distance of 8 mm or more from the developer holding member, and is swingably mounted around the rotary drive shaft 26. This swinging movement agitates the magnetic particles rising along the inner surface of the developer supply container of the magnetic blade 15 and causes them to fall to the lower part of the developer supply container. At this time, since the magnetic particles on the top surface of the base layer are removed, the gravitational force applied to the magnetic particles from above is reduced,
As a result, the magnetic particles in the vicinity of the magnetic blade 15 are pushed up < 1 force more actively, and the circulation force of the entire magnetic particles is improved. Moreover, the stirred magnetic particles 4± take in the non-magnetic developer in their vicinity well, making them non-magnetic. The magnetic developer is sufficiently replenished.

As the agitation means 24, one that performs t± rotational motion in FIG. 2 and one that performs three-wheel oscillation motion in FIG. 5 is used, but the reverse may also be used. The developing method used here is t±JP-A-55-18.
656 is preferred), a voltage is applied between the electrophotographic photoreceptor and the first-stage developer holding member 12 by an IASUMI source 19.The bias power source 19 may be an alternating current or a direct current f. However, it is preferable to have direct current superimposed on alternating current.
The developer provided by the development is supplied from the base layer 16 to the developer holding member 12, and the insufficient amount in the base layer 16 is supplied from the developer layer 17 by the above-mentioned circulation movement.

In the case of a two-layer structure, the base layer 16 is formed near the outer surface of the developer holding member 12 from the beginning, and the developer layer 17 either does not contain any magnetic particles or contains magnetic particles unavoidably as the device is used. Since the amount is small enough to compensate for the loss of magnetic particles that occurs during operation, the state of the magnetic brush in the base layer 16 remains approximately constant and does not change even if the operation continues for a long period of time. In this sense, the magnetic particles in base layer 16 are part of the development apparatus rather than the developer material or part thereof.

The image density does not depend on the weight ratio of the magnetic particles in the developer and the developer that actually formed the image in the above example
Consistent and good images were obtained. At the same time, environmental tests have confirmed that the developing device has low environmental dependence.

In the above explanation, a magnetic blade made of a magnetic material such as iron is used as the regulating member, but a non-magnetic blade made of a non-magnetic material such as aluminum, copper, or resin or a non-magnetic material such as resin or aluminum constituting the container is used. The wall of the body can also be used as this regulating member. However, in this case, in order to prevent the magnetic particles from flowing out, it is necessary to make the gap between the sleeve and the regulating member even smaller than when using a magnetic blade. Further, when a magnetic blade is used, it is preferable because a magnetic brush can be stably formed at the developer outlet by the magnetic field between the blade and the magnetic pole.

As described above, according to the present invention, the stirring means 24 can sufficiently stir the magnetic particles and take in the non-magnetic developer, and moreover, the non-magnetic developer can be reliably tripo-electrified. Because it tightens, there is no fogging or white spots in the developed image.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a developer thin layer forming apparatus to which the present invention can be applied. FIG. 2 is a cross-sectional view of a developer thin layer forming apparatus according to the present invention. FIG. FIG. 4 is a cross-sectional view of the structure in which the position of the stirring means 24 is changed; FIG. FIG. Explanation of symbols: Electrophotographic photoreceptor 12: Developer holding member 13: Developer supply container 14; Fixed magnetic field generating means 15: Magnetic particle restraining member 162 Base layer 17: Non-magnetic developer layer 20: Magnetic particle restraining magnetic pole 1 Father-in-law? Figure 3 (2) Figure 4

Claims (1)

[Scope of Claims] A developer supply container having an opening; a developer holding non-magnetic member provided in the opening and movable endlessly inside and outside the container; and a fixing member provided inside the holding member. a magnetic field generating means; a base layer containing magnetic particles formed on the developer holding member inside the developer supply container and capable of holding developer thereon; and a base layer provided on the outside of the developer holding member and fixed thereto. A developer comprising: a magnetic particle restraining member that restrains the base layer of magnetic particles within a developer supply container together with a magnetic field generating means; and a member that stirs an interface between the base layer and the developer above the base layer. Thin layer forming device: 6. .