JPH10198161A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of substantially applying only non-magnetic toner on a developing sleeve by stabilizing the charge application to the non-magnetic toner by the friction between magnetic carriers, and binding the magnetic carrier in the developer container. SOLUTION: In the developing device adopting the developer containing the non-magnetic toner and the magnetic carriers, magnetic field is formed by the developer carrier 1 having magnetism in cooperation with the permanent magnet 10 by rotating the developer controlling member 2 composed of a non- magnetic member 2 provided with a permanent magnet 10 fixed inside. The magnetic carriers are bound in the developer controlling area G formed by the magnetic field while the transporting force in the developer container inside direction is applied, positively circulated, and substantially the non-magnetic toner only is carried by the developer carrier 1 and transported to the developing area for developing the latent image on the image carrier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a developing device used for an electrophotographic image forming apparatus, an electrostatic recording apparatus, and the like.

[0002]

2. Description of the Related Art Conventionally, as a developing system used in, for example, an electrophotographic image forming apparatus, US Pat.
A number of developing methods have been proposed, such as the magnetic brush developing method described in Japanese Patent No.

[0003] For example, as a developing system using a one-component developer, a so-called “Japanese Patent Application Laid-Open No. 54-43036”
A development method known as "jumping development method" has been proposed and put into practical use. This developing method uses a developer containing a toner in which a magnetic substance is internally added, and it is difficult to use a color toner having high saturation, and is not suitable for forming a color image.

On the other hand, as a one-component developing method using a non-magnetic toner, an impression developing method has been proposed and put into practical use. These developing methods are advantageous for forming a color image because a toner containing a magnetic substance is not used when developing an electrostatic latent image.

However, in any one of the above-described one-component developing methods, in order to form a good image, it is important to impart a sufficient amount of charge to the toner for development.

Therefore, the toner and the developing sleeve, that is,
In order to increase the chance of contact with the developer carrying member that carries and conveys the toner, and to provide the toner with a triboelectric charge amount sufficient for development, a thin layer of developer is applied onto the developer carrying member. ing.

For example, in a developing method using a magnetic toner,
As described in JP-A-54-43037, a uniform thin layer coating of a developer is carried out on a developer carrier by a so-called "magnetic cut system" utilizing regulation of the developer by a magnetic field. Is possible.

On the other hand, in a developing method using a non-magnetic toner, a magnetic field cannot be used to apply a uniform thin layer of the developer on the developer carrying member, and therefore, a mechanical or Generally, the developer is regulated using an electric field. For example, as described in JP-A-54-43038, it is possible to mechanically control the toner layer thickness by using an elastic blade or a leaf spring as a doctor blade. However, it is not easy to set the developer regulation by an elastic blade or the like. For example, when the pressure on the developer carrier such as the elastic blade is too low, a predetermined toner layer thickness cannot be obtained, and If too much, the damage of the toner becomes remarkable. or,
Strict management of the contact state of an elastic blade or the like is required for uniform application of the developer.

In order to solve such a problem of charge application to the developer, a developing method described in Japanese Patent Application Laid-Open No. Sho 60-42776 has been devised. This developing method uses a two-component developer composed of a non-magnetic toner and a magnetic carrier, and constrains the magnetic carrier in a developer container by a magnetic field. The latent image on the image carrier is developed by conveying the toner to a developing area. The non-magnetic toner is provided with a sufficient charge for development by frictional charging with the magnetic carrier and the surface of the developer carrier. An example of a developing device using this developing method will be described next with reference to FIG.

The developing device of this embodiment includes a developing container 5 for storing a developer, and an opening of the developing container 5 formed at a position facing the image carrier 100 is rotatable in the direction of the arrow in the figure. A developing sleeve 1 as a developer carrier made of a non-magnetic member is arranged. In this developing sleeve 1,
The permanent magnet 10 is fixedly arranged. A developer regulating blade 2 made of a magnetic material is disposed above the developing sleeve 1 so as to face the surface of the sleeve. Below the developing sleeve 1 is a squeeze sheet 6 for preventing leakage of the developer from inside the developing container 5. Is arranged. Further, in the developing container 5,
A stirring rod 3 that rotates in the direction of the arrow in the drawing and stirs the developer in the developing container 5 is provided. The magnetic blade 2
Are arranged with a certain gap from the developing sleeve 1, and the distance W is set to a value within a range of 100 μm to 500 μm.

The application of the developer to the developing sleeve 1 in the developing device having such a configuration will be described below.

That is, the magnetic carrier in the developer is restrained by the magnetic field formed by the permanent magnet 10 disposed in the developing sleeve 1 and the magnetic blade 2 in cooperation, so that the developing sleeve 1 and the magnetic blade A developer regulating region G is formed in a region on the upstream side with respect to the developer conveying direction from a portion adjacent to the second region. FIG. 9 shows an enlarged view of the developer regulating region G.

The magnetic carrier C in the developer in the developer regulating area G receives the above-mentioned magnetic field, and thereby the permanent magnet 1
A magnetic brush is formed in a path from the magnetic pole N of 0 to the magnetic blade 2 to form a series of magnetic circuits. Therefore, the magnetic carrier C does not leak into the developing area where the developing sleeve 1 and the image carrier 100 are opposed to each other, but stays in the developer container 5.

On the other hand, the non-magnetic toner T in the developer is not restricted by the magnetic field in the developer regulating area G.
Further, the non-magnetic toner T is subjected to a mirror force from the developing sleeve 1 due to the electric charge given by the frictional charging between the magnetic carrier C and the surface of the developing sleeve 1. Therefore,
The non-magnetic toner T receives a conveying force in the rotation direction of the developing sleeve with the rotation of the developing sleeve 1, passes between the magnetic brushes in the developer regulating area G, and is applied onto the developing sleeve 1. You.

According to the above-described principle, substantially only the non-magnetic toner T can be applied onto the developing sleeve 1.

[0016]

However, in the above-described conventional developing device, when image formation is continuously performed, the density of an output image may be reduced and toner may be scattered. Further, this problem occurs remarkably when an image is formed at a high speed. A cause of such a problem is a decrease in the charge amount of the non-magnetic toner T applied on the developing sleeve 1.

According to the study of the present inventor, in the configuration of the conventional developing device described above, the magnetic carrier C is restrained by the magnetic field to prevent the magnetic carrier C from leaking onto the developing area. It is unavoidable that the magnetic carrier C in the developer substantially forms an immobile layer in the developer regulating region G. Therefore, the circulation of the magnetic carrier C in the developer regulating region G is very gentle, so that when the toner is remarkably consumed by the image formation or when the image formation is accelerated, the developer regulation is suppressed. The agitation and mixing of the non-magnetic toner T newly supplied to the region G and the constrained magnetic carrier C cannot keep up, and the charge application by frictional charging becomes insufficient. Therefore, the insufficiently charged toner T is applied onto the developing sleeve 1, and
It was found that the density of the output image was reduced and toner was scattered.

For the purpose of smoothing the circulation of the developer and achieving sufficient triboelectric charging, a permanent magnet 10 having a small magnetic flux density can be used, or the magnetic blade 2 and the developing sleeve 1 can be used.
When the binding force of the magnetic carrier C in the developer regulating region G is weakened by increasing the distance W of the gap between
It was found that the magnetic carrier C leaked to the development area.

Further, in the above-mentioned conventional developing device, when a developing sleeve having a small diameter is used in order to reduce the size and cost of the developing device, the permanent magnet disposed inside the developing sleeve is also small, so It is not easy to generate a magnetic field sufficient to regulate the agent. Moreover, the small diameter (outer diameter 16
mm) than when a developing sleeve is used.
As can be understood from FIGS. 10 (A) and 10 (B), which show a case where a developing sleeve having a small diameter (0 mm) is used, when a developing sleeve having a small diameter is used (FIG. 10 (A)), a permanent Since the area where the lines of magnetic force are concentrated is narrowed due to the restriction of the size of the magnet 10, the amount of developer regulated in the developer regulating area G is reduced. This may affect the regulation state of the agent, causing leakage of the magnetic carrier, variation in the amount of applied toner, and the like. Therefore, when a developing sleeve having a small diameter is used, it is particularly necessary to stably form the developer regulating region G. In order to generate a sufficient and uniform magnetic field, a permanent magnet using a rare earth element compound can be used. However, it is very expensive, and this is a major obstacle in reducing the size and cost of the developing device. Was.

Accordingly, an object of the present invention is to solve the above-mentioned problems, stabilize the charge application to the non-magnetic toner by friction with the magnetic carrier, and restrain the magnetic carrier in the developer container. Accordingly, an object of the present invention is to provide a developing device capable of applying substantially only a non-magnetic toner on a developing sleeve.

Another object of the present invention is to stably charge a non-magnetic toner by friction with a magnetic carrier.
An object of the present invention is to provide a small and inexpensive developing device capable of applying only a non-magnetic toner on a developing sleeve by sufficiently constraining a magnetic carrier in a developer container.

[0022]

The above object is achieved by a developing apparatus according to the present invention. In summary, the present invention provides a developer container containing a developer containing a non-magnetic toner and a magnetic carrier, a developer carrier having magnetism rotatably disposed for carrying and transporting the developer, A developer regulating member constituted by a non-magnetic member and arranged rotatably to regulate the application of the developer on the developer carrying member, and a magnetic field generating means arranged inside the developer regulating member, The developer is regulated by a magnetic field formed in cooperation with the developer carrier and the magnetic field generating means magnetized by the magnetic field generating means, so that substantially only the non-magnetic toner is removed. The developing device is applied on the developer carrier.

According to a preferred embodiment of the present invention, the developer carrying member has a roller shape formed of a magnetic member or a cylindrical shape formed of a non-magnetic member, and has a magnetic material inside. It is configured to have a member. Preferably, the developer carrying member has a cylindrical shape formed of a non-magnetic member, and has a configuration having a magnetic member inside.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 shows a first embodiment of the developing device of the present invention. In this embodiment, the developing device includes a developing container 5 for storing a developer, and an opening of the developing container 5 formed at a position facing the image carrier 100 is rotatable in a direction indicated by an arrow in FIG. A developing roller 1 as a developer carrier, and a regulating sleeve 2 as a developer regulating member are arranged above the developing roller 1 with a gap of a predetermined distance W from the developing roller 1. The regulating sleeve 2 is made of a non-magnetic member, and is rotatably supported in the same direction as the rotation direction of the developing roller 1. A permanent magnet 10 is fixedly disposed in the regulating sleeve 1. . A scraper 3 that contacts the regulating sleeve 1 is attached to the upper end of the opening of the developing container 5, and a squeeze sheet 4 for preventing leakage of the developer from the inside of the developing container 5 is provided at the lower end of the opening of the developing container 5. Be placed. Further, in the developing container 5, there is provided a conveying member 4 which rotates in the direction of an arrow in the figure and agitates the developer in the developing container 5 and supplies the developer to the developing roller 1. As the developer, a so-called two-component developer containing a non-magnetic toner having a volume average diameter of 8 μm and a magnetic carrier having a volume average diameter of 45 μm was used.

In this embodiment, the developing roller 1 has an outer diameter of 20 mm.
The regulating sleeve 2 is a cylinder made of a non-magnetic material having an outer diameter of 20 mm, and the developing roller 1 and the regulating sleeve 2 are opposed to each other with a gap of a distance W therebetween. I have. This distance W is 100 μm
It is set to a value within the range of ５００500 μm. The permanent magnet 10 disposed in the regulating sleeve 2 has an S pole located near the position where the developing roller 1 and the regulating sleeve 2 are opposed to each other, and another magnetic pole, not shown in FIG. It has two poles.

According to the configuration of the present invention, the developing roller 1 and the permanent magnet 10 cooperate to form a magnetic field in which magnetic lines of force are concentrated around the vicinity of the developing roller 1 and the regulating sleeve 2. As a result, a developer regulating region G is formed.
In the developing device of this embodiment, a gap W having a distance W of 150 μm, a magnetic pole S having a magnetic flux density of 1000 G and a half width of 35 ° was used.

Next, the manner of applying the non-magnetic toner on the developing roller 1 in the developing device having the above-described configuration will be described.

That is, in the developing device of this embodiment, the developer stirred by the transport member 4 from the developer container 5 and supplied onto the developing roller 1 receives the magnetic force of the permanent magnet 10 in the regulating sleeve 2. After being carried and conveyed on the magnetized developing roller 1, the developer is regulated in the developer regulating region G described above. FIG. 2 is an enlarged view of the developer regulating region G.

The magnetic carrier in the developer bound by the magnetic field in the developer regulating area G is bound by the magnetic force of the magnetic pole S of the permanent magnet 10 in the regulating sleeve 2.
Since the regulating sleeve 2 is rotating in the direction of the arrow shown in FIG. 2, the magnetic carrier receives a conveying force in the direction (A) of returning to the developer container with the rotation. Accordingly, the magnetic carrier is constrained in the developer regulating region G, but is conveyed by the regulating force from the regulating sleeve 2.
In order to be sequentially returned toward the developer container, the developing roller 1
Is circulated in the developer container as indicated by an arrow A in FIG. 2 without leaking to the developing area facing the image carrier 100.

On the other hand, the non-magnetic toner in the developer in the developer regulating region G is not restricted by the magnetic field in the developer regulating region G. In addition, the non-magnetic toner is affected by the reflection force from the developing roller 1 due to the electric charge given by the frictional charging between the magnetic carrier and the surface of the developing roller.
Accordingly, the non-magnetic toner receives a conveying force in the rotation direction (B) of the developing roller 1 with the rotation of the developing roller 1, and passes between the magnetic brushes in the developer regulating area G, It is applied onto the developing roller 1.

As described above, it is possible to apply only the non-magnetic toner, which has been given a sufficient charge for development, on the developing roller 1 without leakage of the magnetic carrier.

When images were continuously formed using the developing device of this embodiment, as shown in FIG. 3, even when the number of output sheets was 5,000, the density of the output image did not decrease and toner scattering did not occur. Good image formation could be performed.
On the other hand, in the conventional developing device, when the number of output sheets exceeds 500, the density of the output image rapidly decreases, and toner scattering occurs.

As described above, according to the developing device of the present embodiment, the charge application to the non-magnetic toner due to the friction with the magnetic carrier is stabilized, and the magnetic carrier is restrained in the developer container. Thus, it is possible to apply substantially only the non-magnetic toner on the developing roller.

Embodiment 2 FIGS. 4 and 5 show a second embodiment of the developing device of the present invention. The developing device of this embodiment is the same as that of the first embodiment except that the outer diameter of the developing roller 1 as a developer carrier is reduced in order to make the developing device smaller than the developing device of the first embodiment. The configuration is the same as that of the developing device shown.

In other words, in the present embodiment, the regulating sleeve 2 as the developer regulating member has an outer diameter of 20 mm, which is the same as that in the first embodiment, except that the developing roller 1 is a developer carrying member. The outer diameter is 16 mm, which is smaller than in the case of the first embodiment. The permanent magnet 10 disposed inside the regulating sleeve 2 is located near the position where the developing roller 1 and the regulating sleeve 2 face each other, and has a magnetic flux density of 850 G and a half width of 3.
A 5 ° pole S and another pole, not shown in FIG. 4, were used.

A magnetic field in which the lines of magnetic force are concentrated is formed in the vicinity of the developing roller 1 and the regulating sleeve 2 in cooperation with the developing roller 1 as a magnetic member and the permanent magnet 10 in the regulating sleeve 2. The developer control area G
Is formed. FIG. 5 is an enlarged view of the developer regulating region G. In the developer regulating region G, the binding and circulation of the magnetic carrier and the application of the non-magnetic toner on the developing roller 1 are performed.

According to the study of the present inventor, the regulation sleeve 2
On the other hand, when the developing roller 1 having a small diameter is used, the concentration of lines of magnetic force from the permanent magnet 10 in the regulating sleeve 2 on the developing roller 1 is improved, and the magnetic pole S having a magnetic flux density of 850 G is used. However, a stable developer control region G was formed. Further, even when the rotation speed of the developing roller 1 is 1.5 times as large as that of the developing device in the first embodiment, there is no leakage of the magnetic carrier into the developing area, and the smooth circulation state of the magnetic carrier is maintained. The formation was confirmed.

Therefore, in the developing device of the present embodiment, in order to use the same image forming speed as the developing device of the first embodiment, the rotation speed of the developing roller is set to 1.
When driven at 25 times and continuous image formation was performed,
No decrease in the density of the output image and no toner scattering occurred, and good image formation was possible.

As described above, according to the developing device of this embodiment, it is possible to stabilize the charge application to the non-magnetic toner by friction with the magnetic carrier, and to restrain the magnetic carrier in the developer container. Thus, it is possible to apply substantially only the non-magnetic toner on the developing roller, and it is compact.

Embodiment 3 FIGS. 6 and 7 show a third embodiment of the developing device of the present invention. The developing device of this embodiment has the same configuration as the developing device shown in the first embodiment except that the configuration of the developer carrier is different.

That is, in the present embodiment, the regulating sleeve 2 which is a developer regulating member has an outer diameter of 20 mm, and has a permanent magnet 10 inside the regulating sleeve 2. But the developer carrier has an outer diameter of 20
A developing sleeve 1A made of a non-magnetic material having a thickness of 1 mm was used, and a magnetic member 11 was disposed inside the developing sleeve 1A near a position facing the regulating sleeve 2. The permanent magnet 10 has a magnetic flux density of 85
A magnetic pole S having 0 G and a half-width of 35 ° and another magnetic pole (not shown in FIG. 6) were used.

The magnetic member 11 in the developing sleeve 1A and the permanent magnet 10 in the regulating sleeve 2 cooperate to form a concentrated magnetic field of the magnetic field lines in the vicinity of the developing sleeve 1A and the regulating sleeve 2. The developer regulating region G is formed by the magnetic field. FIG. 7 shows an enlarged view of the developer regulating region G. In the developer regulating region G, the binding and circulation of the magnetic carrier and the developing sleeve 1 for the non-magnetic toner are controlled.
Application on A is performed.

Further, in the developing device of this embodiment, even if the magnetic member 11 in the developing sleeve 1A is attracted by the magnetic field of the permanent magnet 10 in the regulating sleeve 2 and "deflection" occurs, the developing sleeve 1 itself is not deformed. Since it is a non-magnetic member, it is not affected by a magnetic field, and the gap between the developing sleeve 1A and the regulating sleeve 2 is kept constant, so that non-uniform application of the developer does not occur.

As described above, it is possible to uniformly apply only the non-magnetic toner, which has been charged sufficiently to be used for development, onto the developing sleeve 1A without the magnetic carrier leaking to the developing area. it can.

When images were continuously formed using the developing apparatus of the present embodiment, the density of the output image did not decrease and toner scattering did not occur, and good image formation could be performed.

As described above, according to the developing device of the present embodiment, it is possible to stabilize the charge application to the non-magnetic toner by friction with the magnetic carrier and to restrain the magnetic carrier in the developer container. Thus, it is possible to apply substantially only the non-magnetic toner on the developing roller.

The present invention is not limited to the developing devices described in the above embodiments, but can be applied to a wide range of general developing devices.

[0049]

As described above, the developing device of the present invention is a developing device that uses a developer containing a non-magnetic toner and a magnetic carrier, and includes a non-magnetic member having a permanent magnet fixed inside. By rotating the developer regulating member, the magnetic carrier is restrained in the developer regulating region G formed by the magnetic field formed by the developer carrier having magnetism and the permanent magnet cooperating with each other. Direction (A)
And positively circulates, and substantially only the non-magnetic toner is carried on the developer carrying member and is carried in the direction (B) of the developing area to develop the latent image on the image carrying member. As a result, it is possible to stabilize the charge application to the non-magnetic toner due to friction with the magnetic carrier, and to substantially develop only the non-magnetic toner by keeping the magnetic carrier in the developer container. The effect of being able to be applied on the sleeve and being small and inexpensive can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a developing device according to the present invention.

FIG. 2 is an enlarged view of the vicinity of a developer regulating area G of the developing device of FIG.

FIG. 3 is a graph showing output image density fluctuation when continuous image formation is performed using the developing device of the present invention and a conventional developing device.

FIG. 4 is a schematic configuration diagram of a second embodiment of the developing device according to the present invention.

FIG. 5 is an enlarged view of the vicinity of a developer regulating region G of the developing device of FIG. 4;

FIG. 6 is a schematic configuration diagram of a third embodiment of the developing device according to the present invention.

7 is an enlarged view of the vicinity of a developer regulating region G of the developing device of FIG. 6;

FIG. 8 is a schematic configuration diagram of a conventional developing device.

FIG. 9 is an enlarged view of the vicinity of a developer regulating region G of a conventional developing device.

FIG. 10 is a diagram illustrating an example of a correlation between the diameter of a developer carrying member (developing sleeve) and the range of a developer regulating region G in a conventional developing device. FIG.
6B, and the outer diameter of the developing sleeve is 2 mm in FIG.
0 mm.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developer carrier 2 developer regulating member 5 developing container 10 magnetic field generating means 11 magnetic member 100 image carrier

Claims (4)

[Claims] A developing container containing a developer containing a non-magnetic toner and a magnetic carrier; a developer carrier having a magnet rotatably disposed to carry and transport the developer;
A developer regulating member formed of a non-magnetic member and arranged rotatably to regulate the application of the developer on the developer carrying member; and a magnetic field generating means disposed inside the developer regulating member. Wherein the developer is regulated by a magnetic field formed in cooperation with the developer carrier and the magnetic field generating means magnetized by the magnetic field generating means, so that substantially only the non-magnetic toner is used. Is applied onto the developer carrier. 2. The developing device according to claim 1, wherein said developer carrier has a roller shape formed of a magnetic member. 3. The developing device according to claim 1, wherein the developer carrier has a cylindrical shape formed of a non-magnetic member, and has a magnetic member therein. 4. The developing device according to claim 1, wherein said developer carrier has a cylindrical shape formed of a non-magnetic member, and has a magnetic member therein.