JPH0434576A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a developer from being leaked from a gap between both end parts of a developing sleeve and a developing container by providing a magnetic body generating a concentrated magnetic field between a magnet and the body itself so as to surround both end parts of a developer carrier and be inclined outward in the shaft direction of the developer carrier in an opening out state. CONSTITUTION:A tie platelike magnetic body 12 which is bent so as to surround the developing sleeve 3 by almost semicircle length along the outer periphery of the developing sleeve 3 except a place opposite to a photosensitive drum 1, is provided on the places of both end parts of the developing sleeve 3, on the main body side wall 10 of this developing device 2. The magnetic body 12 is arranged so that the peripheral part 12A inside it facing the magnetized region of a magnetic roller 4 inside the developing sleeve 3, and inclined outward in the shaft direction from the peripheral part 12A in the opening out state, at an inclined angle theta with respect to the developing sleeve 3, so that an interval with respect to the developing sleeve 3 spreads outward in the shaft direction at both end parts of the developing sleeve 3. Thus, the developer can be easily prevented from being leaked by scattering from the gap between both end parts of the developer carrier and the developing container.

Description

[Detailed Description of the Invention] No. 1 The present invention relates to a developing device used in an electrophotographic copying device,
In particular, it relates to a developing device with improved developer leakage ratio and scattering prevention means.

In an electrophotographic copying apparatus, an electrostatic latent image formed on an image carrier is developed to visualize the electrostatic latent image as a toner image.

In a developing device that performs such development, the developer contained in the developer container is supported on the outer peripheral surface of a developing sleeve with a built-in magnet installed in the developer container to form a developer layer. The developer layer is conveyed to the developing area by rotation, and the electrostatic latent image formed on the photosensitive drum facing the developing sleeve in the developing area is developed with the developer and visualized as a toner image. It has become.

However, the developing sleeve in the above-mentioned developing device has a gap between it and the developing container at both ends, and if left as is, the developer will scatter and leak from the gap, so it is necessary to prevent the developer from leaking. It is necessary to prevent this.

Conventionally, a method for preventing developer leakage has been to fill the gap between both ends of the developer sleeve and the developer container with a sponge-like elastic member or felt-like cloth as a sealing member. However, in this method, since the developing sleeve rotates, the developer gets between the elastic member or cloth and the developing sleeve, so developer leakage still occurs, and the rotational torque of the developing sleeve is also reduced. It also had the disadvantage of causing an increase in the amount of water, and was not effective.

In addition, the abrasion resistance of the elastic member and cloth described above is poor, and debris such as lint is generated, and these fragments form lumps with the developer toner and move to the image area, which deteriorates the quality of the copied image. was declining.

Other methods that have been considered include forming both ends of the developer regulating plate into a special shape or providing magnetic members at both ends of the regulating plate. Furthermore, other measures have been taken, such as providing grooves at both ends of the developing sleeve, and making the surface roughness of the developing sleeve different between the inside of the image area at both ends and the outside of the image area at the outside of both ends.

However, these methods are not sufficiently effective and must be used in conjunction with the method of filling with sealing material such as an elastic member or cloth, which complicates the means to prevent developer leakage and increases the cost of the developing device. Invite high. Further, in a developing device used in a high-speed copying machine, the temperature increase at both ends of the developing sleeve and the increase in the torque of the developing sleeve cannot be ignored, making it difficult to apply this method.

Therefore, an object of the present invention is to easily prevent developer from leaking due to scattering from the gap between both ends of a developing sleeve and a developing container without complicating a leakage prevention means, and to prevent the leakage of a copied image. It is an object of the present invention to provide a developing device that does not reduce quality.

The above-mentioned object is achieved by the developing device according to the present invention. To summarize, the present invention has a structure in which a magnet provided in a main body of a developing device is used to support a built-in cylindrical developer carrier on a developer contained in a developer container, and transfer the developer to a developing area facing the image carrier. In a developing device that conveys and develops a latent image formed on the image carrier with the developer, a magnetic body that generates a concentrated magnetic field between it and the magnet is attached to the developer carrying body of the developing device main body. The developing device is provided at both end portions of the developing device so as to surround the both end portions and to be inclined to open outward in the axial direction of the developer carrier. The magnetic body has an inclination angle of 5 to 60 degrees.

1F Examples of the present invention will be described in detail below.

FIG. 1 is a cross-sectional view showing the entire developing device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the end portion of the developing sleeve of the developing device shown in FIG. 1, and FIG. , which is also a longitudinal sectional view.

As shown in FIG. 1, the present developing device 2 is arranged such that a one-component developer 9 made of magnetic toner is stored in a developing container 6 at an arrow a.
A developing sleeve 3 that rotates in the direction of the arrow mark is provided facing the photosensitive drum 1 that rotates in the direction of the arrow. A magnetic roll 4 as a magnet is immovably disposed inside the developing sleeve 3, and a magnetic roller 4 is placed on the top of the developing sleeve 3 to measure the layer thickness of the developer layer formed by supporting the developer 9 on the developing sleeve 3. A spike control plate 7 made of a magnetic material and arranged at a predetermined distance from the developing sleeve 3.

The magnetic roll 4 has a plurality of magnetic poles consisting of N poles and S poles arranged alternately, of which the N pole faces the regulation plate 7 to form a regulation pole, and the S and poles are arranged around the photosensitive drum 7. A developing pole is formed in a developing area where the developing sleeve 3 and the developing sleeve 3 face each other.

A bias power source 8 is connected to the developing sleeve 3 . The bias power supply 8 applies a developing bias to the developing sleeve 3 to form an alternating electric field in which alternating current is superimposed on direct current in the developing area between the photosensitive drum 1 and the developing sleeve 3 .

When the developing sleeve 3 rotates, the magnetic field of the internal magnetic roller 4 attracts the developer 9, the developer 9 is carried on the surface of the developing sleeve 3, and the layer thickness of the carried developer 9 is increased. A thin layer of the developer 9 is formed on the developing sleeve 3 by being regulated by the magnetic action of the regulating plate 7 and the regulating pole N. The thin layer of developer 9 is transported as the developing sleeve 3 rotates, and reaches a development area having a wider interval than the thin layer of developer 9, and the alternating electric field formed by the bias power supply 8 described above is applied to the thin layer of developer 9. As a result, the developer 9 flies from above the developing sleeve 3 and adheres to the electrostatic latent image on the photosensitive drum 1 to develop the electrostatic layer image and visualize it as a toner image.

The blistering regulating plate 7 is fixed between the side walls 10 constituting the main body of the developing device 2, and the distance between the lower end of the regulating plate 7 and the surface of the developing sleeve 3 is 0°1 to 0.5 mm (7 mm). ) maintains a gap. In this example, an iron blade was used as the regulating plate 7, and the above-mentioned gap was set to 0.24 mm. As a result, in this embodiment, the magnetic pole N is placed on the developing sleeve 3.
, , S, a thin layer of developer 9 was formed with a thickness of 70 to 80 μm.

Now, according to the present invention, as shown in FIG. A curved strip-shaped magnetic body 12 is provided along the outer circumferential surface of the magnetic body so as to surround it by approximately half the circumference. Magnetic material 12
is preferably maintained at the same potential as the developing sleeve 3 in order to prevent electrical leakage between the developing sleeve 3 and the developing sleeve 3.

According to this embodiment, the magnetic body 12 is arranged such that its inner peripheral edge 12A faces the magnetized region of the magnetic roller 4 in the developing sleeve 3, and as shown in FIG. 30 is opened outwardly from the peripheral edge 12A at an inclination angle θ to the developing sleeve 3 so that the distance between the developing sleeve 3 and the developing sleeve 3 widens outward in the axial direction indicated by the rotating shaft 5 at both ends. It is slanted. The upper circumferential end 12B of the magnetic body 12 is where the developer 9 is carried out from the developer container 6 by the developing sleeve 3 (the developer 8 mouth end side), and the other circumferential end 12B located below The circumferential end 12c is a developer entrance end where the developer 9 is returned into the developer container 6 by the developer sleeve 3.

When such a magnetic body 12 is provided at both ends of the developing sleeve 3, a concentrated magnetic field is formed between the magnetic roller 4 in the developing sleeve 3 and the inner peripheral edge 12A of the magnetic body 12, and the concentrated magnetic field is generated by the magnetic body. The developer 9 is blocked from passing outward through the inner peripheral edge 12A of the developer 9. Therefore, the developer 9 does not scatter and leak from the developer container 6 at both ends of the developer sleeve 3. In order to install the magnetic body 12 to block the passage of the developer 9 and prevent leakage, the closest distance between the developing sleeve 3 and the magnetic body 12 must be 0.1 to 1.0 m.
m is effective, and in this example, it was set to 0°5 mm.

Preventing leakage of the developer 9 by installing the magnetic body 12 in this embodiment will be further explained.

FIG. 4 is a longitudinal sectional view of the end of the developing sleeve of a developing device similar to FIG. 3, showing a comparative example of the method of installing the magnetic body 12.

In the installation method of this comparative example, the magnetic body 12 is installed almost perpendicularly to the developing sleeve 3. According to such installation of the magnetic body 12, a magnetic circuit is formed between the magnetic pole of the magnetic roller 4 in the developing sleeve 3 and the magnetic body 12 not only at the inner peripheral edge 12A of the magnetic body 12 but also at other locations. is formed, the concentrated magnetic field at the peripheral edge portion 12A of the magnetic body 12 is weakened.

Therefore, the effect of preventing the developer 9 from leaking from both ends of the developing sleeve 3 is considerably reduced.

In addition, the movement of the developer 9 in the developer container 6 deteriorates near both ends of the developing sleeve 3, reducing the agitation and mixing effect of the developer 9, and the developer 9 on the developing sleeve 3 and the developing sleeve 3 Replacement of the replenished developer 9 becomes difficult. For this reason, the charge imparted by the developer 9 to the toner particles by frictional charging is reduced, or conversely, excessive charging occurs, which tends to cause ground blur, reverse fog, and thin density on the copied image. . These occurrences are particularly noticeable when the developer 9 is a one-component developer.

FIG. 5 shows a third comparative example of the method of installing the magnetic body 12.
FIG. 3 is a longitudinal cross-sectional view of the end portion of the developing sleeve of the developing device similar to that shown in the figure.

In the installation method of this comparative example, the magnetic body 12 is installed substantially parallel to the developing sleeve 3. In order to install the magnetic body 12 in this manner, it is necessary to maintain the magnetic body 12 at a constant distance from the surface of the developing sleeve 3 over a wide area, which is difficult in terms of mechanical configuration. Also, when a larger foreign object enters the gap between the magnetic material 12 and the developing sleeve 3, the developing sleeve 3
may damage or damage the surface of the magnetic material 12, etc.

On the other hand, in the present embodiment shown in FIGS. 1 to 3, the method of installing the magnetic body 12 does not have the drawbacks of the comparative example, and therefore, it is possible to obtain a good copy image without ground force blur or the like.

That is, in this embodiment, the magnetic roller 4 in the developing sleeve 3
A concentrated magnetic field is formed between the inner peripheral edge 12A of the magnetic body 12, and the formation of a magnetic circuit between the magnetic body 12 and other parts other than the peripheral edge 12A is weak. Unlike the installation method, the movement of the developer 9 in the developer container 6 does not deteriorate near both ends of the developer sleeve 3. Furthermore, since it is possible to form a magnetic field in a direction that obstructs the movement of the developer 9 that attempts to move along the axial direction of both ends on the surface of the developing sleeve 3, the developer 9 at both ends of the developing sleeve 3 can be prevented from moving.
The leakage prevention effect works well. Further, since the closest portion of the magnetic body 12 to the developing sleeve 3 is only at the peripheral edge portion 12A, there is no drawback as in the installation method of another comparative example shown in FIG. In particular, the magnetic body 1 is placed at the end of the magnetized area of the magnetic roller 4.
Since the inner circumferential edges 12A of the magnetic rollers 2 and 2 face each other, a strong magnetic binding force acts, reducing the dimensional overlap between the magnetic body 12 and the magnetic roller 4, and improving the axial magnetization of the magnetic roller 4. There is no need to set the dimensions large.

An effective inclination angle θ of the magnetic body 12 shown in FIG. 3 is 5 to 60 degrees. If the above-mentioned inclination angle θ is less than 5 degrees, there will be no substantial difference from the installation method shown in FIG. 5, and similar problems will occur. If the angle of inclination θ exceeds 60 degrees, the same problem as in the installation method shown in FIG. 4 will occur. Therefore,
The inclination angle θ of the magnetic body 12 is preferably 5 to 60 degrees, preferably 10 to 45 degrees.

As the magnetic body 12, for example, an iron plate, a magnetic stainless steel plate, etc. are suitable. In this example, an iron plate with a thickness of 2 mm was used. Note that the formation area of the thin layer of developer 9 on the developing sleeve 3 can be effectively set up to the intersection where the extension line of the magnetic body 12 intersects with the surface of the developing sleeve 3.

FIG. 6 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to another embodiment of the present invention.

This embodiment is characterized in that the magnetic material 12 is extended and bent in a dogleg shape along the outer surface of the main body side wall 10 of the developing device 2, so that the magnetic material 12 is provided up to the outer surface of the side wall member 10. It is. The other points of this embodiment are the same as those of the embodiment shown in FIGS. 1-3.

According to this embodiment, since the magnetic body 12 is provided up to the outer surface of the main body side wall 10 of the developing device 2, its volume can be increased. As a result, the developer 9 at both ends of the developing sleeve 3 can be strengthened.
The magnetic suppression force against leakage can be increased to improve leakage prevention. Another advantage is that the magnetic body 12 can be easily fixed to the side wall 10.

FIG. 7 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to still another embodiment of the present invention.

In this embodiment, the position of the circumferential end 12C of the lower side of the magnetic body 12, which is the developer inlet end side where the developer 9 is returned into the developer container 6 by the developer sleeve 3, is axially outward of the developing sleeve 3 by a distance m from the circumferential end 12B located above the magnetic body 12, which is the developer outlet end side where the developer 9 is carried out from the developing container 6. It is characterized by being shifted to Therefore, the inner peripheral edge 12A of the magnetic body 12 appears as a diagonal line as shown by the broken line. The other points of this embodiment are the same as those of the embodiment shown in FIGS. 1-3.

According to this embodiment, the ends of the thin layer of developer 9 coming out of the spike control plate 7 expand outward in the axial direction at both ends of the developing sleeve 3 as the developing sleeve 3 rotates, but the magnetic material Since the end 12C on the developer inlet end side of the developer sleeve 3 is shifted outward in the axial direction of the developing sleeve 3, it is magnetically restrained by the end 12C of the magnetic body 12, and therefore the developer container for the developer 9 is It is possible to more reliably prevent the developer 9 from leaking from the end portion 12C during collection into the developer 6.

FIG. 8 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to still another embodiment of the present invention.

This embodiment is characterized in that the tip end shape of the inner peripheral edge 12A of the magnetic body 12 is a knife shape that is continuous with the inner surface of the main body side wall 10 of the developing device 2. The other points of this embodiment are the same as those of the embodiment shown in FIGS. 1-3.

For example, in the case of the embodiment shown in FIGS. 1 to 3, a minute space is formed between the inner tip of the main body side wall 10 of the developing device 2, the inner peripheral edge 12A of the magnetic body 12, and the surface of the developing sleeve 3. However, according to this embodiment, since this minute space can be eliminated, leakage of the developer 9 at both ends of the developing sleeve 3 can be more reliably prevented. Furthermore, since there is no microspace, it is possible to prevent the formation of a bulge at the end of the thin layer of developer 9 formed on the developing sleeve 3, thereby making it possible to form a uniform thin layer of developer 9. I can do it.

In each of the above embodiments, a case is shown in which a -component magnetic developer is used as the developer 9, but the present invention provides a case in which a two-component developer consisting of a magnetic carrier and a non-magnetic toner or a magnetic toner is used. It was also possible to obtain similar good results.

Further, although a curved continuous plate in the form of a strip is used as the magnetic body 12, the shape is not limited to this, and the magnetic body may be composed of, for example, a plate that is not curved and is divided into several pieces.

Further, although a rigid metal body is used as the magnetic body 12, the present invention is not limited to this, and magnetic powder may be dispersed in brass or rubber material. In particular, when the magnetic material 12 is made of a rubber material with magnetic powder dispersed in it, the magnetic material 12 will not be damaged even if the magnetic material 12 comes into slight contact with the developing sleeve 3. The gap between the sleeve 3 and the sleeve 3 can be narrower or the sleeve 3 can be brought into contact with the sleeve 3, and the leakage prevention effect of the developer 9 can be further improved. It is also possible to make a composite type magnetic material by fixing the rubber material in which the above-mentioned magnetic powder is dispersed to a magnetic or non-magnetic metal rigid body. In this case, the rubber material is placed between the developing sleeve 3 and the metal rigid body. located in

Furthermore, the prevention of leakage of the developer 9 using a conventionally used sealing member such as a sponge-like elastic member or a felt-like cloth can be used in combination with the leakage prevention using the magnetic body 12 according to the present invention.

In that case, by using these seal members with the contact pressure against the developing sleeve 3 reduced, it was possible to further improve the prevention of leakage of the developer 9 in combination with the effects of the present invention.

As explained above, in the developing device of the present invention, as the developer leakage means, a magnetic material that generates a concentrated magnetic field between it and the magnet built in the developer carrier on the leakage prevention means cylinder is used. The developer carrier is provided at both ends of the developer carrier of the developing device main body so as to surround both ends of the developer carrier and to be inclined outward in the axial direction of the developer carrier. It is possible to easily prevent developer from scattering and leaking from the gap between both ends of the carrier and the developer container. Conventionally, in the case of developing devices used in high-speed copying machines, methods to prevent developer leakage using sealing members such as sponge-like elastic members ignored the increase in torque of the developer carrier and the temperature rise at both ends. However, since the developer leakage prevention according to the present invention is a non-contact type, there is no such difficulty and it can be easily applied, which is particularly advantageous.

Further, according to the magnetic material used in the present invention, unlike when a seal member is used, shape, dimensional accuracy, and mounting accuracy to the developer carrier can be relaxed, and further, mounting to the side wall of the main body of the developing device is easy. It is also easy to use and is useful when manufacturing and assembling mechanical components.

Furthermore, the method for preventing developer leakage according to the present invention has no adverse effect on the formation of a developer layer on a developer carrier, and a uniform and stable developer layer can be formed, resulting in good image quality. You can get a good image. -In the case of component developers,
It is important to form a developer layer on a developer carrier with a sharp width without disturbance at the edges, and this is possible according to the present invention, and therefore it can be applied to a developing device using a one-component developer. It is particularly useful for

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the entire developing device according to an embodiment of the present invention. 2 is a perspective view showing the end portion of the developing sleeve of the developing device shown in FIG. 1. FIG. FIG. 3 is also a longitudinal sectional view. FIG. 4 is a longitudinal cross-sectional view of the end of the developing sleeve of the developing device similar to FIG. be. FIG. 5 is a longitudinal sectional view similar to FIG. 4 showing another comparative example of the method of installing the magnetic material. FIG. 6 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to another embodiment of the present invention. FIG. 7 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to still another embodiment of the present invention. FIG. 8 is a longitudinal sectional view showing the end portion of a developing sleeve of a developing device according to still another embodiment of the present invention. : Photosensitive drum: Developing device: Magnetic roller: Developing container: Standing regulation plate: Side wall of developer body 2: Magnetic material Figure 6

Claims (1)

[Scope of Claims] 1) A magnet provided in the main body of the developing device carries the developer contained in the developer container on a built-in cylindrical developer carrier, and transfers the developer to the developing area facing the image carrier. In a developing device that conveys a latent image formed on the image carrier with the developer, a magnetic body that generates a concentrated magnetic field between it and the magnet is attached to the developer carrying body of the developing device main body. A developing device, characterized in that the developing device is provided at both end portions of a body so as to surround the both end portions and to be inclined to open outward in the axial direction of the developer carrier. 2) The developing device according to claim 1, wherein the magnetic body has an inclination angle of 5 to 60 degrees.