JP2003195641A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To seal developer without spoiling the planarity of a developer restricting blade by sealing a space formed between a developer container and an attaching base of the developer restricting blade in a non contact method. <P>SOLUTION: A developer retaining member consisting of a magnetic material is provided on the developer container side in a position where the developer container and the developer restricting blade are faced. Between the developer retaining member and the developer restricting blade is provided a very small space. A magnetic field is generated in this space due to magnetic force generated by a magnet roll in a developing sleeve, the developer is restrained by this magnetic field and sealing is carried out so that the developer is not leaked outside. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer, a recorded image display for developing an electrostatic latent image formed on an image carrier by an electrophotographic system, an electrostatic recording system or the like to form a visible image. The present invention relates to a developing device in an image forming apparatus such as an apparatus and a facsimile.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, a dry developer as a developer is carried on the surface of a developer carrying member, and the surface of the image carrying member carrying an electrostatic latent image is near the surface of the developer carrying member. It is well known that the developer is conveyed and supplied, and the electrostatic latent image is developed and visualized while applying an alternating (alternating) electric field between the image carrier and the developer carrier.

A developing sleeve is generally used as the developer carrying member, so that it is referred to as a "developing sleeve" in the following description. Further, a photosensitive drum is generally used as the image carrying member in many cases. Therefore, the term "photosensitive drum" is used in the following description.

As the above-mentioned developing method, conventionally, for example, 2
A magnetic brush was formed on the surface of a developing sleeve having a magnet inside by a developer (two-component developer) composed of a component system composition (carrier particles and toner particles), and a small developing gap was held to face each other. This magnetic brush is rubbed or brought close to the photosensitive drum, and an alternating electric field is continuously applied between the developing sleeve and the photosensitive drum (between S and D), so that the toner particles are transferred from the developing sleeve side to the photosensitive drum side. Development by repeatedly performing dislocation and inversion.
The so-called magnetic brush developing method is known (see, for example, JP-A-55-3060 and JP-A-59-165082).

The developing device for developing the two-component magnetic brush mainly has a structure as shown in FIG. In the figure, 75 is a developing sleeve, 79 is a magnet roller fixedly arranged in the developing sleeve, 86 and 87 are stirring screws, 78 is a regulating blade arranged to form a thin layer of developer on the surface of the developing sleeve 75, 81 Is a developing container, and 71 is a hopper for storing toner. The developing sleeve 75 is disposed close to the photosensitive drum 3, rotates in the opposite direction to the photosensitive drum 3 as shown in the figure, and can be developed in a state where the developer is in contact with the photosensitive drum 3. Is set.

The developing device 82 contains a developer 85 in which toner particles and magnetic carriers are mixed, and the mixing ratio (hereinafter T / C ratio) of the toner particles and magnetic carriers is the toner consumed by the development. An amount of toner commensurate with the above is dropped and replenished from the hopper 71 in which the replenishment toner 83 is stored, so that it is kept constant. Development container 82 at this time
As a method of detecting and maintaining the mixing ratio of the toner particles and the magnetic carrier therein, for example, a sensor 93 is provided in the developing container 82, and the inductance of the coil is utilized to make apparent magnetic permeability μ of the developer within a certain volume near the sensor. Detect changes,
A device that detects a T / C ratio (hereinafter referred to as a toner concentration detection sensor) and the like have been proposed and put into practical use. on the other hand,
A motor as a drive source for driving the developing sleeve 75 and the agitation screws 86, 87, and a gear train (not shown) for transmitting the drive are configured.

[0007]

However, in the above-mentioned conventional example, a slight gap is generated between the regulation blade 78 and the mounting surface on the side of the developing container 81 due to dimensional accuracy, flatness, etc., from which development is performed. There was a problem that the agent 85 leaked out. Therefore, the regulating blade 78 is attached to the developing container 8
Measures have been taken such as bonding to No. 1 to eliminate the gap, or inserting an elastic member such as moltoprene into the gap to fill the gap. However, when it is difficult to adjust the mounting position of the regulation blade 78 for defining the thickness of the developer layer formed on the surface of the developing sleeve 75, or when the developing container 81 is deformed for some reason, the developing sleeve is not deformed. The gap (SB gap) between 75 and the regulation blade 78 follows the deformation of the developing container 81 and fluctuates. Therefore, it is difficult to maintain the thickness of the developer layer stably, and there is a problem that the image density varies. Further, the flatness of the regulating blade 78 is impaired by the reaction force of compressing the elastic member, and the thickness of the developer layer becomes uneven in the longitudinal direction, causing image defects such as uneven density.

[0008]

In order to solve the above problems, the present invention has a plurality of magnetic field generators fixedly arranged therein.
A rotatable developer carrier that carries and conveys a developer containing a magnetic material, and a developer carrier that is disposed so as to face the developer carrier and regulates the amount of the developer carried by the developer carrier. In a developing device having a regulating blade partially having a magnetic material, and a developing container supporting the developer carrying member and the regulating blade and accommodating a developer, the developing blade is opposed to the regulating blade of the developing container. A developer holding member made of a magnetic material is fixedly provided in the developing container over the longitudinal direction of the portion where the developer is leaked to prevent the developer from leaking.

As the developer holding member, a steel plate, preferably a steel plate for spring material is used so that the developer can be magnetically held.

Alternatively, as the developer holding member,
A magnet is used so that a stronger magnetic field can be generated to magnetically retain the developer.

The developer holding member is provided with a minute gap of 1 mm or less with respect to the regulation blade so as not to come into direct contact with the regulation blade.

The above-mentioned structure is shown again in the following (1) to (5).

(1) A plurality of magnetic field generators are fixedly arranged inside, a rotatable developer carrier for carrying and transporting a developer containing a magnetic material, and a developer carrier arranged opposite to the developer carrier. And a regulation blade that regulates the amount of the developer carried on the developer carrying body, and has a magnetic body at least in part,
In a developing device having a developer container supporting the developer carrying member and the regulating blade and accommodating the developer, a magnetic material is provided in a longitudinal direction of a portion of the developing container facing the regulating blade. A developing device, wherein a developer holding member consisting of is fixed to the developing container.

(2) The developing device according to (1), wherein the developer holding member is a steel plate, preferably a steel plate for spring material.

(3) The developing device as described in (1) above, wherein the developer holding member is arranged in a direction substantially orthogonal to the regulating blade.

(4) The developing device described in (1), wherein the developer holding member is a magnet.

(5) The developing device according to (1), wherein the developer holding member is provided with a gap of 1 mm or less with respect to the regulation blade.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on examples with reference to the drawings.

FIG. 1 is a sectional view of a developing device applicable in the present invention. The developing device 32 includes a developing container 31, the inside of which is divided into a developing chamber R1 and a stirring chamber R2 by a partition wall 44, and a hopper 21 arranged above the stirring chamber R2 has a toner storage chamber R3. Replenishment toner 33 is stored. From the replenishing port 34 at the lower part of the toner storage chamber R3, an amount of toner commensurate with the toner consumed in the development is dropped and replenished into the stirring chamber R2. On the other hand, in the developing chamber R1 and the stirring chamber R2, the developer 35 in which the toner particles and the magnetic carrier are mixed is contained.

A developer conveying screw 36 is housed in the developing chamber R1 and conveys the developer 35 along the longitudinal direction of the developing sleeve 25 by rotational driving. The conveying direction of the developer 35 by the screw 37 housed in the developing chamber R2 is opposite to that by the screw 36. The partition wall 44 has openings on the front side and the back side, and the developer 35 carried by the screw 36 is delivered to the screw 37 from one of the openings, and the developer 35 carried by the screw 37 is It is delivered to the screw 36 from the other one of the above openings. A toner concentration detection sensor 43 is installed on the wall surface of the stirring chamber R2 so as to face the screw 37. As the toner concentration detection sensor 43, for example, as described in (Prior Art), a sensor that detects the magnetic permeability of the developer 35 by utilizing the inductance of the coil is used.

An opening is provided in a portion of the developing container 31 close to the photosensitive drum 3, and the opening is a cylinder made of a material such as aluminum or non-magnetic stainless steel, and has an appropriate unevenness on its surface. A non-magnetic developing sleeve 25 is provided.

In the present invention, the developing sleeve 25 rotates at the peripheral speed Vb in the direction of the arrow b (the direction opposite to the rotating direction of the photoconductor), and the layer thickness regulating blade 28 at the lower end of the opening of the developing container 31 allows proper development. After being regulated to the developer layer thickness, the developer 3
5 is carried and conveyed to the developing area 39. The magnetic brush of the developer 35 carried on the developing sleeve 25 comes into contact with the photoconductor 3 rotating at the peripheral speed Va in the direction of arrow a in the developing area 39, and the electrostatic latent image is developed in this developing area 39. The peripheral speed Vb of the developing sleeve 25 is 130 to 200% of the peripheral speed of the photosensitive drum.
Is desirable, and more preferably 150-180%. In the range below the above range, sufficient image density cannot be obtained, and above that range, the developer 35 is scattered. A roller-shaped magnet 29 is fixedly arranged in the developing sleeve 25. The magnet 29 has a developing magnetic pole N1 facing the developing area 39. A magnetic brush of the developer 35 is formed by the developing magnetic field formed in the developing region 39 of the developing magnetic pole N1, and the magnetic brush comes into contact with the photosensitive drum 3 to develop the electrostatic latent image.
At that time, the toner adhering to the magnetic brush and the toner adhering to the surface of the sleeve are also transferred to the image area of the electrostatic latent image and developed. In this embodiment, the magnet 29 has S1, S2, S3 and N2 poles in addition to the developing magnetic pole N1. With such a configuration, the developing sleeve 25 is similar to the conventional one.
The developer 35 applied at the S3 pole by the rotation of the magnetic field passes through the regulation blade 28 and reaches the developing magnetic pole N1, and the developer 35 which is erected in the magnetic field develops the electrostatic latent image on the image carrier 3. To do. After that, the developer 35 on the developing sleeve 25 is conveyed from the S1 pole to the N2 pole, and further due to the repulsive magnetic field between the S2 pole and the S3 pole, drops into the developing chamber R1. Development room R1
The developer 35 that has dropped inside is agitated and conveyed by screws 36 and 37.

Further, the regulating blade 28 is provided with a developing container 31.
The blade base 27 fixed to the blade base 27 is fixed with screws. Here, the blade base 27 is a non-magnetic member and is made of a plate material such as a stainless steel plate. On the other hand, the regulation blade 28 is a member made of a magnetic material, and is, for example, a cold-rolled steel plate (SPCC) plated with chemical nickel. Alternatively, a member of a magnetic material may be integrated with a part of a non-magnetic stainless steel plate by a method such as caulking.

Next, the details of the present invention will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional view of the tip portion of the regulation blade 28 on the developing sleeve 25 side.

The regulating blade 28 is fixed to the developing sleeve 25 with a minute gap (SB gap) of 300 to 500 μm, and regulates the amount of the developer 35 passing therethrough. It defines the layer thickness of the developer 35 coated on. On the other hand, the blade base 27 to which the regulation blade 28 is attached is attached to the c-face of the developing container 31, but it does not necessarily come into close contact depending on dimensional accuracy such as flatness of the c-face, and a gap d is generated. There is. Further, the flatness of the regulation blade 28 is impaired because the surface of the blade base 27 is wavy due to the flatness of the c-plane, or the developing container 31 is bent due to thermal deformation or the like. In order to avoid the problem that a uniform S-B gap cannot be maintained due to the gap d
May be provided.

In such a case, the developer 3 is discharged from the gap d.
Although there is a concern that 5 may leak out, in the present invention, the magnetic material 51 is arranged as a developer holding member to seal it.

As the material of the magnetic body 51, a steel plate such as SPCC is used. Alternatively, if a thin plate is required due to space constraints, SK4P-MQ or SK5
It is preferable to use a steel plate for spring material such as P-MQ from the viewpoint of handling. In any case, it is preferable to plate chemical nickel or the like as a rust countermeasure.

The magnetic body 51 is arranged over the entire area in the longitudinal direction corresponding to the opening provided in the developing container 31. Therefore, the effects described below can be expected in any cross section in the longitudinal direction, and the sealability of the developer 35, which is the object of the present invention, can be achieved.

As shown in FIG. 2, the magnetic body 51 is adhesively fixed to the developing container 31 with a space e from the regulating blade 27. Here, the interval e is set to 1 mm or less, preferably 0.5 mm or less. If this distance e is large,
A magnetic force, which will be described later, of the developer 35 cannot be sufficiently obtained, and the sealing property is deteriorated. If the gap is not provided, the developing container 31 may be bent due to thermal deformation or the like as described above, and the magnetic body 51 and the regulation blade 28 interfere with each other to impair the flatness of the regulation blade 28. However, the problem of the prior art that the uniform S-B gap cannot be maintained due to the above problem cannot be solved.

FIG. 5 shows the result of simulation analysis of the magnetic field generated in the vicinity of the magnetic body 51. Development sleeve 2
Part of the magnetic field lines extending from the magnet 29 provided in
It can be seen that the (.103) enters the magnetic body 51 and then faces the regulating blade 28. The developer 35, which tends to leak out of the developing container 31 in question, is restrained by this magnetic field, stays in the F portion, and does not move downward. Therefore, it is prevented from going out of the container without entering the gap d.

Further, the magnetic force lines that contribute to restraining the developer 35 which is about to leak are located far away from the SB gap portion, and the presence of the magnetic body 51 causes the magnetic force lines near the SB gap. Has no effect. Therefore, the coating amount of the developer 35 related to the image quality can be handled in the same manner as the conventional technique.

These have been confirmed from the results of examination by putting them in an actual machine. The present invention establishes a technique for sealing the developer 35 with a simple structure and in a non-contact manner with the regulating blade 28. I was able to.

As for the arrangement of the magnetic body 51, in order to concentrate the lines of magnetic force and obtain a strong magnetic field, the regulating blade 2
It is preferable to arrange them in a direction substantially perpendicular to 8. However, depending on space restrictions and the like, a larger area than the magnetic blade 52 shown in FIG.
A wide magnetic field is secured by facing the developer 3
5, the same effect can be obtained even if the developer 5 is constrained, or if a magnetic body having a larger volume such as the magnetic body 53 shown in FIG. .

(Second Embodiment) As a material of the developer holding member, a magnet is more preferable.

FIG. 6 shows the result of a similar simulation analysis with the magnet 55 of the same shape being replaced with the magnetic body 51 of the previous embodiment. In the present embodiment, the magnet 29 in the developing sleeve 25 has the N pole as the developing magnetic pole and the S pole on the side opposite to the regulating blade 28.
The S pole is arranged on the side facing the regulating blade 28 of No. 5 and the N pole is arranged on the opposite side, so that the magnetic force lines act more effectively.

From this result, more magnetic field lines (111
It can be seen that (~ 117) enters the magnet 55 and faces the regulation blade 28. Therefore, a stronger magnetic field is generated in the G portion, and the developer 35 attempting to leak is more firmly restrained in the G portion. Therefore, a stronger sealing property can be expected.

[0037]

As described above, according to the present invention,
A plurality of magnetic field generators are fixedly arranged inside, and a rotatable developer carrier that carries and conveys a developer containing a magnetic material, and a developer carrier that is arranged opposite to the developer carrier. A regulating blade that regulates the amount of the developer carried on the body and has a magnetic body at least in part, and a developing container that supports the developer carrying body and the regulating blade and contains the developer. In the developing device, the developer holding member made of a magnetic material is fixedly provided in the developing container over the longitudinal direction of the portion of the developing container facing the regulating blade, so that the inside of the developer carrying member is provided. It was possible to locally concentrate a part of the magnetic field generated by the arranged magnetic field generator to hold the developer and prevent the developer from leaking.

Further, as the developer holding member, a steel plate, preferably a steel plate for spring material is used, and a technique capable of magnetically holding the developer with an inexpensive structure has been established.

Alternatively, a magnet can be used as the developer holding member, and a stronger magnetic field can be generated to magnetically hold the developer.

Further, the developer holding member is provided so as to have a minute gap of 1 mm or less with respect to the regulation blade, and the developer is sealed so as not to come into direct contact with the regulation blade. The technology to do this was established.

[Brief description of drawings]

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a developer holding member according to an embodiment of the present invention.

FIG. 3 is a sectional view of a second developer holding member according to an embodiment of the present invention.

FIG. 4 is a sectional view of a third developer holding member according to an embodiment of the present invention.

FIG. 5 is a diagram showing a magnetic field in the vicinity of a developer holding member according to an embodiment of the present invention.

FIG. 6 is a diagram showing a magnetic field in the vicinity of a developer holding member according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a conventional developing device.

[Explanation of symbols]

3 photosensitive drum 25 Development sleeve 27 blade base 28 Regulation blade 29 magnets 31 developer container 32 developer 34 Supply port 35 developer 36, 37 screw 39 Development area 43 Toner concentration detection sensor 44 partition R1 development room R2 stirring room R3 toner storage room 51, 52, 53 developer holding member (magnetic material) 55 Developer Holding Member (Magnet) 71 hopper 75 Development sleeve 78 Regulation blade 79 Magnet roller 81 developer container 82 Developer 83 Replenishment toner 85 Developer 86,87 stirring screw

Claims (5)

[Claims] 1. A plurality of magnetic field generators are fixedly arranged inside, a rotatable developer carrier for carrying and transporting a developer containing a magnetic material, and a rotatable developer carrier opposed to the developer carrier. A regulation blade that regulates the amount of the developer carried on the developer carrying body, and has a magnetic body at least partially
In a developing device having a developer container supporting the developer carrying member and the regulating blade and accommodating the developer, a magnetic material is provided in a longitudinal direction of a portion of the developing container facing the regulating blade. A developing device, wherein a developer holding member consisting of is fixed to the developing container. 2. The developing device according to claim 1, wherein the developer holding member is a steel plate, preferably a steel plate for spring material. 3. The developing device according to claim 1, wherein the developer holding member is arranged in a direction substantially orthogonal to the regulation blade. 4. The developing device according to claim 1, wherein the developer holding member is a magnet. 5. The developing device according to claim 1, wherein the developer holding member is provided with a gap of 1 mm or less with respect to the regulation blade.