JPS61175663A - Developing device - Google Patents

Abstract

PURPOSE:To obtain a uniform thin layer of a developer which is charged electrostatically and sufficiently by friction and to prevent effectively the developer from leaking from a developing device by setting a seal member longer in lengthwise length at the downstream side of a developer holding member in its rotating direction than at its upstream side. CONSTITUTION:The seal member 26 is provided to the overall length of a magnetic member so as to block the gap between a sleeve 12 and a magnetic member 22. The direction of the seal member 22 coincides with the rotating direction of the sleeve 12 and the seal member is arranged at the downstream side of the magnetic member 22 so that it comes into surface contact elastically with the sleeve 12 in the middle. The length L from the tip of the magnetic member is set preferably to >=4mm.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Summary of the Invention The present invention relates to a developing device for developing a latent image such as an electrostatic latent image using a non-magnetic developer.

Various types of dry-component developing devices have been proposed and put into practical use. However, in any of the development methods, it is extremely difficult to form a thin layer of dry component developer, and for this reason, a developing device has been configured with a relatively thick layer. However, as improvements in the clarity and resolution of developed images are currently being sought, it is essential to develop a method for forming a thin layer of a dry component developer and an apparatus therefor.

As a conventionally known method for forming a thin layer of a dry component developer, Japanese Patent Application Laid-Open No. 54-43037 has been proposed.
And it has been put into practical use. However, this concerned the formation of a thin layer of magnetic developer. In order to make the Fn developer magnetic, it is necessary to add a magnetic material internally. There are problems such as poor color reproduction during color reproduction.

For this reason, as a method for forming a thin layer of non-magnetic developer, there are two methods: using a cylindrical brush made of soft bristles like beaver's hair, and applying the developer to the brush. A method of coating the developing roller with a doctor blade or the like has been proposed. 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. Furthermore, since the device includes a non-magnetic developer, it is difficult to prevent the developer from leaking from the device.

1 to 11 The present invention eliminates the problems of the conventional method described above, and provides a new developing device that forms a uniform thin layer of developer on the surface of a developer holding member and applies sufficient triboelectric charging. It is intended to. A further object of the present invention is to make it possible to prevent the non-magnetic developer from leaking out of the developing device.

According to the present invention, there is provided a developer supply container having an opening, and an interior and an exterior of the container provided in the opening.

An endlessly movable non-magnetic member for holding developer, a fixed magnetic field generating means provided inside the holding member, and a fixed magnetic field generating means provided outside the developer holding member together with magnetic particles inside the developer supply container. A magnetic particle restraining member is provided on the developer return side of the container to restrain a magnetic particle forming a magnetic brush, and a magnetic particle restraining member is provided in a gap between the magnetic member and the developer holding member to restrain the developing a sealing member that is in surface contact with the holding member in a forward direction relative to the rotational direction of the holding member on the downstream side of the magnetic member in the rotational direction of the agent holding member; Since there is provided a developing device characterized in that the length in the direction of rotation of the developer holding member is made longer on the downstream side than on the upstream side in the rotational direction, a uniform thin layer of developer with sufficient frictional electrification can be obtained. , developer can be effectively prevented from leaking from the developing device.

The latent image carrier of the present invention is a drum-shaped or belt-shaped member having a photoconductor or an insulating layer, and the magnetic field generating means is a magnetic roller having magnetic poles of the same or different polarity in the axial direction. Alternatively, a plurality of rod-shaped magnets bonded to a fixed support member may be used. Furthermore, as the rotating developer holding member, it is possible to use a sleeve made of non-magnetic metal such as aluminum, stainless steel, brass, etc. or a synthetic resin material, or an endless belt made of resin or metal. In order to improve the electrostatic properties and charging properties, the surface may be roughened or provided with an uneven pattern as necessary.1. As the magnetic particle restraining member, magnetic materials such as iron, or non-magnetic materials such as aluminum, copper, resin, etc. A body blade plate or wall may be used.

Furthermore, when providing a magnetic member facing the magnetic field generating means to form a magnetic brush for preventing the developer from flowing out, a magnetic member other than metal such as iron may be used, which faces the magnetic field generating means in a relationship of opposite polarity. These magnetic members may be attached to the wall of the container opposite the magnetic field generating means.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a sectional view of a developing device to which the present invention is applicable.

In FIG. 1, numeral 11 is a cylindrical electrophotographic photoreceptor that moves in the direction of arrow a. A non-magnetic sleeve 12 serving as a developer holding member is provided with a gap between the photoreceptor 11 and the photoreceptor 11 . This sleeve 12 rotates in the direction of the arrow as the photoreceptor 11 moves. A fixed magnet 13 is provided in the sleeve 12 as a magnetic field generating means. 14 is a hole serving as a developer supply container, and the sleeve 12 is used to store non-magnetic developer 15 and magnetic particles 1.
It contains a developer mixture having 6.

A magnetic brush made of magnetic particles 16 is formed near the surface of the sleeve 12 corresponding to the magnetic pole 17 of the magnet 13. When the sleeve 12 is rotated in the direction indicated by the arrow, by appropriately selecting the arrangement position of the magnetic pole 17 and the fluidity and magnetic properties of the magnetic particles 16, the magnetic brush circulates in the direction of the arrow C near the magnetic pole 17, causing circulation MI18. form.

On the other hand, at a point 19 downstream of the 111 pole 17 in the sleeve rotation direction, a magnetic blade 21 as a magnetic particle restraining member made of a magnetic material is placed at a distance from the sleeve 12 at a point 19.
The blade is arranged to be inclined downstream in the direction of movement of the sleeve, with an angle δ formed between the blade and l with respect to the modulus un of the sleeve 12 at the position. The magnetic particles 16 have a binding force based on gravity, magnetic force, and the effect of the presence of the magnetic blade 21;
It is restrained at a point 19 on the surface of the sleeve 12 by balancing with the conveying force in the moving direction of the sleeve 12, forming a stationary layer 20 that can move to some extent but is almost immobile. A magnetic particle layer consisting of the circulating layer 18 and the stationary layer 20 is formed on the surface of the sleeve 12. The magnetic particle layer contains a non-magnetic developer 5, and the magnetic particles in the stationary layer 20 are restrained on the sleeve surface by the balance between the restraining force and the conveying force described above, but since the developer is non-magnetic, , is not restrained by the magnetic field of the magnetic pole 17, and is coated uniformly and thinly on the sleeve surface by the reflection force, and is transported as the sleeve rotates, and the photoreceptor 1
1 and subjected to development.

Circulation j! ) 1B, one ring of the magnetic brush is performed as shown by arrow C due to the magnetic force and frictional force due to gravity and magnetic poles, and the fluidity (viscosity) of the magnetic particles, and the magnetic brush is on top of the magnetic particle layer during this circulation. The principle of this method for forming a thin layer of developer, in which the non-magnetic developer 15 is taken in from the developer layer and returned to the lower part of the developer supply container 14, and this cycle is repeated, is described in Japanese Patent Application No. 58-151028 filed by the present applicant. Because I am familiar with the issue.

Detailed explanation will be omitted.

At the bottom of the container 14, a non-magnetized magnetic member 22 is provided, one end of which faces the direction of the magnetic field of the magnetic pole 17 of the magnet 13, and between the magnetic pole 17 and the magnetic member 22, magnetic particles are A magnetic brush is formed to prevent developer or magnetic particles from leaking from the magnetic member 22 to the upstream side in the direction of rotation of the sleeve.

However, due to vibrations of the developing device or shocks caused by external factors, some magnetic particles may leak upstream in the rotational direction of the sleeve, resulting in the magnetic brush spreading toward the upstream side.

2 and 3 are diagrams illustrating a magnetic brush formed by the magnetic field between the magnetic pole 17 and the magnetic member 22. FIG. Some magnetic particles 16 leak out due to vibrations of the device or shocks caused by external factors, resulting in the state shown in FIG. 3.

What is important here is that the function of the magnetic brush is not only to prevent magnetic particles from leaking out, but also to not prevent developer that was not used for development (such as non-image areas) from returning to the container. This is it.

When the magnetic brush faces in the forward direction with respect to the direction of rotation of the sleeve 12 as shown in FIG. 2, the developer 15 that has not been used for development is not scraped off by the magnetic brush, but as shown in FIG. Experiments have revealed that when the magnetic brush has a portion facing in the opposite direction to the direction of rotation of the sleeve 12, a portion of the developer 15 to be collected is scraped off, causing developer scattering.

The present invention provides a developing device free from such developer scattering.

FIG. 4 is a sectional view of a developing device according to an embodiment of the present invention, and FIG. 5 is an enlarged view illustrating the magnetic member portion in detail.

Components that perform the same functions as those in FIG. 1 are denoted by the same reference numerals instead of detailed description.

As shown in FIG. 5, in the present invention, the sealing member 26
is provided over the entire longitudinal direction of the magnetic member so as to close the gap between the sleeve 12 and the magnetic member 22.

The sealing member 26 is oriented in the forward direction of the rotational direction of the sleeve 12, and is in elastic contact with the sleeve 12 on the downstream side (the state shown in FIG. 3 on the upstream side) of the position of the magnetic member 22. It is arranged so that it makes surface contact.

In this embodiment, the sleeve diameter is 20φ, the magnetic member tip position is 20° below the horizontal plane passing through the center of the sleeve, the gap between the sleeve 12 and the magnetic member 22 is 0.8 mm, and the sealing member 26 is made of flat mylar with a thickness of 25 pm. was used, and the length from the tip of the magnetic member was set to 5 mm.

In this configuration, developer scattering at the lower part of the developing device is significantly reduced. It is preferable to set the length L to 4 mm or more. This is because a more favorable effect can be obtained when the seal member 26 makes surface contact with the sleeve 12. If L is 3 mm or less, the edge of the seal member 26 will not touch the sleeve. 12, and this edge scrapes off the developer 15 remaining after development, making it impossible to achieve a significant reduction in the amount of scattering. The preferred range of L varies depending on the distance between the tip of the magnetic member and the surface of the sleeve 12. , it is important that the sealing member is in surface contact with the sleeve 12 .

On the other hand, if L is 6 mm or more, the circulation of the magnetic particles 16 will be disturbed and the coating of the developer onto the sleeve 12 will be adversely affected.

Therefore, in the configuration of this embodiment, 4≦L<6 mm is suitable, but other configurations can also be used as long as the sealing member 26 is in surface contact with the sleeve 12 and the circulation of the magnetic particles 16 is not disturbed. The effect of this can be obtained. Further, in the configuration of this embodiment, the thickness t of the sealing member 26 is preferably 50 lm or less, preferably 25 lm or less. If the sealing member 26 is made thicker, its elasticity becomes stronger, and this sealing member may scrape off the developer on the sleeve.

Although the above configuration can reduce developer scattering, there is a slight scattering problem at the longitudinal ends of the seal member 26.

FIG. 6 is a VI-Vl arrow diagram in FIG. 5, and FIG. 7 shows functions when the present invention is not applied.

As shown in FIG. 6, the end of the sealing member 26 extends to the region of the end felt 27 on the downstream side in the direction of rotation of the sleeve 12. As shown in FIG. That is, the longitudinal length of the seal member 26 is longer on the downstream side than on the upstream side in the rotational direction of the sleeve 12. If this configuration is not adopted, that is, if the configuration shown in FIG. 7 is adopted, the magnetic Member 22
Also, the gap between the end of the sealing member 26 and the felt 27 at both ends of the developer supply container 14 cannot be completely eliminated, and the developer scatters from the end. When the configuration shown in FIG. 6 was tested, developer scattering from the edge was reduced to about 1/l O compared to the configuration shown in FIG. 7.

Note that the shape of the end of the seal member 26 is not limited to this embodiment, and as long as the seal member overlaps with the end felt, it is effective in reducing the amount of developer scattering from the end. .

FIG. 8 shows another embodiment, in which the end of the seal member 26 is attached to the side wall of the developer supply container by the elasticity of the seal member.

In this embodiment, mylar was used as the sealing member 26, but flexible resin sheets such as nylon, polyimide, polycarbonate, vinylon, triacetate, chlorinated rubber, vinyl chloride, moisture-proof cellophane, polyethylene,
It is possible to use a sheet of PTFE or the like.

Moreover, in such a configuration, the magnetic member 22.

The structure of the magnetic brush supports the weight of the magnetic particles 16, and prevents the load of the magnetic particles 16 from being directly applied to the sealing member 26, so that leakage of the magnetic particles 16 to the upstream side of the sleeve can be prevented. It plays a fundamental role, and the sealing member 26 of the present invention supplements it.

The above description has been made regarding the case where the magnetic member is not magnetized, but the free end side of the magnetic member 22 may be magnetized to have a polarity opposite to that of the magnetic pole 17 of the magnet 13.

In this case, the sealing effect by the magnetic member 22 becomes stronger, so there is an overall stronger sealing effect than in the case of non-magnetization. The strength of magnetization at the tip of m stone 22 is 200G~7
Approximately 00G is preferable.

As explained above, according to the present invention, developer leakage, particularly leakage at longitudinal ends, can be reduced.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of a developing device to which the present invention is applicable, FIGS. 2 and 3 show a magnetic brush formed between a magnetic pole and a magnetic member, and FIG. 4 shows an embodiment of the present invention. A sectional view of the developing device is shown, FIG. 5 is an enlarged sectional view illustrating the details of the magnetic member, FIG. 6 is a view shown by the vr-■ arrow in FIG. 5, and FIG. 7 is a case where the present invention is not used. FIG. 8 is a sectional view showing another embodiment of the present invention.
・Magnet, 14...Developer supply container, 15-...
Non-magnetic developer, 16... Magnetic particles, 17.23--
Magnetic pole, 18...φ circulating layer, 20... stationary layer, 21--
-Magnetic blade. 22... Magnetic member, 25-... Power source. Figure 2 Figure 3 Figure 5

Claims (1)

[Scope of Claims] 1) A developer supply container having an opening, a non-magnetic member for holding developer which is provided in the opening and is movable endlessly inside and outside the container, and a non-magnetic member provided inside the holding member. a fixed magnetic field generating means provided on the outside of the developer holding member, a magnetic particle restraining member that is provided on the outside of the developer holding member and restrains the magnetic particles in the developer supply container together with the fixed magnetic field generating means, and provided on the developer return side of the container; A magnetic member forming a magnetic brush is provided in a gap between the magnetic member and the developer holding member, and the magnetic member is arranged downstream of the magnetic member in the rotational direction of the developer holding member. In the forward direction,
A developing device comprising: a sealing member that makes surface contact with the holding member, the length of the sealing member in the longitudinal direction being longer on the downstream side in the rotational direction of the developer holding member than on the upstream side in the rotational direction of the developer holding member. 2) In the developing device according to claim 1,
A developing device, wherein the magnetic member is a magnet.