JP2915593B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for developing and visualizing a latent image on an image carrier in an image forming apparatus such as an electrophotographic system. The present invention relates to a developing device in which a magnetic seal of a developer in a bearing portion of an installed rotating member is improved.

[0002]

2. Description of the Related Art In an image forming apparatus utilizing an electrophotographic system, an electrostatic latent image formed on the surface of an image carrier such as a photoreceptor is developed by a developing device and visualized as a toner image. I have.

As shown in FIG. 3, the conventional developing device has a developing container 104 in which the interior is partitioned by a partition 106 into a stirring chamber 104a and a developing chamber 104b.
The developing roller 101 is rotatably supported by the developing container 104 at the inner upper opening 104c, and is opposed to the photosensitive drum 100 of the image forming apparatus. The developing roller 101 is driven by a driving system (not shown) with respect to the rotating photosensitive drum 100.
And is used for development by rotating in the direction of the arrow shown in the figure.

[0004] Developer conveying screws 102 and 103 are rotatably provided in the stirring chamber 104a and the developing chamber 104b, respectively. The screw 102 in the stirring chamber 104a is rotated by driving by a drive system (not shown), and as shown in FIG. 5 showing a cross section taken along line AA of FIG. The toner supplied from the toner supply port 104d into the stirring chamber 104a is stirred and transported in the direction indicated by the arrow V, and the developer is received in the developing chamber 104b through the opening 106a at the leading end of the partition plate 106 in the direction indicated by the arrow V. hand over. Similarly, the screw 103 in the developing chamber 104b rotates by driving with a drive system (not shown), and conveys the developer delivered from the stirring chamber 10a into the developing chamber 104b in the W direction opposite to the arrow V, An opening 106 at the end of the partition plate 106 in the direction of the arrow W
Return to the stirring chamber 104a through b.

The developer in the developing chamber 104b is pumped up by the rotating developing roller 101 while being conveyed in the direction of the arrow W by the screw 103, and is regulated by the blade 105 brought close to the developing roller 101 to a predetermined level. The developer is applied to a thickness, and a developer layer having a predetermined thickness is formed on the developing roller 101. Then, the developer is conveyed to the opening 104 c of the developing chamber 104 b with the rotation of the developing roller 101, where the developer is supplied to the photosensitive drum 100 and toner adheres to the electrostatic latent image formed on the surface of the photosensitive drum 100. Then, the electrostatic latent image is visualized as a toner image.

In a general developing device, the developer penetrates into a bearing portion of a rotating shaft of a rotating member (for example, screws 102 and 103) provided in a developing container 104 to reduce a rotational load of the rotating member. There has been a problem that the developer which is made heavy or rubbed at the bearing portion solidifies due to frictional heat to form fine coagulated material, which adversely affects the image and causes white spots in the image.

[0007] For this reason, FIG.
As shown in FIG. 5, which is an enlarged view of a portion B of FIG. 5, a carrier chain is formed on a magnetic carrier in the developer by a cylindrical, that is, ring-shaped magnet 113 to prevent the developer from entering the bearing portion. Seal mechanisms have been proposed.

As shown in FIG. 5, a magnetic seal mechanism is provided by screwing magnetic shafts 102b at both ends of a SUS non-magnetic shaft 102a of a rotary shaft 102A main body of a screw 102, and a bearing holder is provided in a recess of a developing container 104. The magnetic shaft 102b is rotatably supported by a bearing 110 which is attached and press-fitted therein, and a ring-shaped magnet 113 which is held by a holder 111 via a spacer 112 is provided in the recessed portion. 113 surrounds the magnetic shaft 102 near the inside of the container 104 with a gap of about 0.5 to 2 mm. This magnet 113 has S, N or N, S in its thickness direction (the same direction as the axial direction of one magnetic shaft portion 102b), or S, N in its radial direction (a direction perpendicular to the axial direction of the magnetic shaft portion 102b). Or N, S.

According to such a sealing mechanism, the magnetic field of the magnet 113 is concentrated on the magnetic shaft 102b,
The magnetic carrier in the developer is attracted to the magnetic field to form a restrained carrier chain, and the space between the inside of the container 104 and the bearing portion provided with the bearing 110 is sealed by the curtain of the carrier chain. With the rotation of the screw 102, a part of the carrier chain is restrained by the magnet 113, and the other part of the carrier chain rotates together with the magnetic shaft part 102b. Soft rubbing, the developer does not form a fine solidified body by the molten toner,
Good sealing of the developer can be achieved.

[0010]

However, in the conventional sealing mechanism, as described above, the screw 10
The magnetic shaft 102b is provided at both ends of the non-magnetic shaft 102a of the main body of the rotating shaft 102A by screwing. That is,
Internal threads are cut at both ends of the non-magnetic shaft 102a,
2b, a male screw is cut into the non-magnetic shaft 102a.
02b is fixed by screwing.

Therefore, the non-magnetic shaft 102a and the magnetic shaft 102
If the processing accuracy of the threaded portion b is not increased, the screw 102 will be bent at the screwed portion, and the screw 102
The screw 102 rotates eccentrically due to a decrease in straightness and coaxiality of the screw, and there is a problem that the conveyance and stirring of the developer by the screw 102 become insufficient.

When the magnetic shaft 102b of the screw 102 is eccentric, the outer peripheral surface of the magnetic shaft 102 and the ring-shaped magnet 1
The gap between the inner peripheral surface of the magnet 13 and the magnet 11 changes.
The magnetic field from No. 3 is not evenly concentrated in the circumferential direction of the magnetic shaft 102b, and the curtain of the carrier chain is deviated in the circumferential direction of the magnetic shaft 102b. Intrusion occurs. As described above, when the developer enters the bearing, the screw 102
And the developer rubbed on the bearing 120 is solidified by frictional heat to form a fine solidified body, which adversely affects the image and causes white spots on the image. .

In view of the above, conventionally, it is necessary to increase the processing accuracy of the threaded portions of the non-magnetic shaft 102a and the magnetic shaft 102b of the screw 102, which causes a decrease in the cost of the developing device, and Non-magnetic shaft 10
Since the work of screwing the magnetic shaft 102b into 2a is required,
This has caused a decrease in assemblability.

Further, the magnetic field from the ring-shaped magnet 113 tends to spread over the entire area of the magnetic shaft 102b. In order to obtain a seal with a strong magnetic field, the magnetic flux density of the magnet 113 must be increased. In fact, it was necessary to use rare earth cobalt-based materials. In order to concentrate the magnetic field on the magnetic shaft 102b, it is necessary to limit the magnetic shaft 102b to only the portion facing the magnet 113. Unless the magnetic shaft 102b has a three-part configuration in which a nonmagnetic shaft is further mounted on the bearing 110 side of the magnetic shaft 102b. Therefore, there is a problem that processing becomes more difficult. Therefore, as will be described in detail later, the present inventor fixes a hollow cylindrical magnetic member 1 on the outer peripheral surface of the rotating shaft 102A as shown in FIG. Open ring-shaped magnet 1 to surround
13, a developing device having a magnetic seal mechanism for the developer in the bearing portion of the rotating shaft 102A was studied. The assemblability of the developing device of this configuration is greatly improved, and the magnetic seal can be performed well. However, the outer peripheral surface of the cylindrical magnetic member 1 and the container are smaller than the portion of the rotating shaft 102A on which the magnetic member 1 is provided. It has been found that when a step is formed between the inner surface and the rotating shaft portion, the rubbing of the developer is concentrated on the step portion and gives frictional heat to the developer.

Therefore, an object of the present invention is to provide a developer container such as a developer conveying screw for a developer container, which does not affect the rotational accuracy of a rotary member installed in a container containing the developer, without affecting the rotational accuracy of the developer in a bearing portion of the rotary member. The gap between the ring-shaped magnet used for the magnetic seal and the magnetic shaft portion of the rotating member is easily ensured, and the frictional resistance to the developer is eliminated, and the bearing of the developer without giving frictional heat to the developer. It is an object of the present invention to provide a developing device which can prevent the intrusion into a portion and can perform a magnetic seal satisfactorily, and furthermore, its assemblability is good and work efficiency can be greatly improved.

[0016]

The above objects are attained by the developing apparatus according to the present invention. In summary, the first aspect of the present invention
According to the aspect, a developer storage container for storing the developer,
A rotating member provided in the developer accommodating container, a bearing portion for receiving both ends of a rotating shaft of the rotating member, and an outer peripheral surface near an end of the rotating shaft, the developer being more than the bearing portion; A cylindrical magnetic member provided inside the storage container,
A developing device having a cylindrical magnet provided so as to surround the magnetic member and a gap, wherein the outer peripheral surface of the magnetic member and the portion of the rotating shaft on which the magnetic member is provided are disposed in the developer accommodating container. There is provided a developing device characterized in that a step is eliminated between the inner rotating shaft portion and the rotating shaft portion. According to a second aspect of the present invention, a developer accommodating container accommodating a developer, a rotating member provided in the developer accommodating container, a bearing for receiving both ends of a rotating shaft of the rotating member, A cylindrical magnet provided on the outer peripheral surface near the end of the rotation shaft and inside the developer accommodating container relative to the bearing, and a cylindrical magnetic member provided so as to surround the magnet with a gap. Wherein the step of eliminating the step between the outer peripheral surface of the magnet and the portion of the rotating shaft inside the developer accommodating container rather than the portion of the rotating shaft where the magnet is provided is characterized in that there is no step. Is provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to the conventional developing device shown in FIGS. 3 and 4, in which the magnetic seal of the developer is performed on the outer peripheral surface of the shaft of the bearing of a rotating member such as the developer conveying screws 102 and 103. In addition, a magnetic member is provided integrally. Therefore, since the basic configuration of the developing device of the present invention is the same as that of the developing device shown in FIGS. 3 and 4, the configuration diagram and the description of the operation of each part are omitted. FIG. 1 is an enlarged view of a bearing portion of a rotary shaft of a screw as a reference example of the developing device of the present invention.

As shown in FIG. 1, also in the developing device of this reference example, a bearing holder 111 is mounted in a concave portion of a developer accommodating container 104, and a rotating shaft 102A of a screw 102 is pressed by a bearing 110 pressed into the bearing holder 111. It is rotatably supported and has a spacer 112 in the recess.
A cylindrical magnet, that is, a ring-shaped magnet 113 held down by a holder 111 is disposed through the hole, and a portion of the rotating shaft 102A of the screw 102 near the inside of the container 104 is set to about 0.5 to 2 mm by the magnet 113. A magnetic seal mechanism is configured to be surrounded at intervals.

According to the present embodiment, the rotating shaft 102A
The whole is a SUS non-magnetic shaft, and the magnetic member 1 is integrally provided on the outer peripheral surface of a portion surrounded by the magnet 113 as described above. The magnetic member 1 is made of a magnetic hollow body obtained by plating a cylindrical pipe made of iron or the like with nickel, and has a thickness of about 0.5 to 2 mm. In order to reduce the deflection of the outer peripheral surface of the magnetic member 1 due to the rotation of the screw 102, the inner diameter of the magnetic material 1 is formed to fit the outer peripheral surface of the rotating shaft 102A, and this is formed on the outer peripheral surface of the rotating shaft 102A. It is fitted and fixed with an adhesive or the like. According to such fixation, the screw 102 is integrated with the magnetic member 1, so that the run-out of the screw 102 itself can be suppressed to be small.

The method of fixing the magnetic member 1 is not limited to the above-described method, and the magnetic member 1 may be press-fitted with the inner diameter smaller than the outer diameter of the rotating shaft 102A.
If knurls are prepared on the inner peripheral surface of the magnetic member 1 and the outer peripheral surface of the rotating shaft 102A, the magnetic member 1 can be prevented from coming off and the strength during rotation can be further ensured. Magnetic member 1
Is larger than the outer diameter of the rotating shaft 102A, a magnetic member 1 is placed on the outer peripheral surface of the rotating shaft 102A, and then swaging is performed by hitting and swaging from above while rotating the screw 102. You may do it. Alternatively, the inner diameter of the magnetic member 1 is made smaller than the outer diameter of the rotating shaft 102A, and the inner diameter is expanded by heating the magnetic member 1 to cover the outer circumferential surface of the rotating shaft 102A, and then fixed by cooling. May be performed. Further, the magnetic member 1 may be fixed to the rotating shaft 102A by using a fixing member such as a pin penetrating the rotating shaft 102A and the magnetic member 1. Retaining rings such as E-shaped rings and G-rings can also be used.

The magnetic seal mechanism in the developing device of this embodiment is constructed as described above. According to this, the screw 1
Since the hollow cylindrical magnetic member 1 is fixed on the outer peripheral surface of the non-magnetic rotating shaft 102A of No. 02, a magnetic portion is integrally provided at a position surrounded by the ring-shaped magnet 113 of the rotating shaft 102A. Unlike the case where the shaft is provided by screwing, the straightness of the rotating shaft 102A is not reduced, and the rotation accuracy of the screw 102 can be kept high without being affected. The gap between the two can be easily ensured. For this reason, the magnetic field of the magnet 113 concentrates on the portion of the magnetic member 1 of the rotating shaft 102A, and the magnetic carrier in the developer is attracted to the magnetic field and the restrained carrier chain is deviated in the circumferential direction of the magnetic member 1. Without bearing, the inside of the container 104 and the bearing 110
The space between the bearing and the bearing portion provided with the seal is well sealed by the curtain of the carrier chain. And screw 102
A part of the carrier chain becomes magnet 1
13 and the remaining part is the magnetic shaft part 102.
b, the rubbing of the developer in the bearing portion provided with the bearing 110 becomes a soft rubbing between the developers, and the developer does not form a fine solidified body by the molten toner. Good developer sealing can be achieved.

Further, according to the present embodiment, since a screwed portion for providing a magnetic shaft on the rotating shaft 102A becomes unnecessary, the assemblability of the developing device is improved, and the length of the hollow magnetic member 1 can be changed. Accordingly, the concentration of the magnetic field of the magnet 113 can be relatively easily achieved, so that the sealing property can be easily increased, the magnetic flux density of the magnet 113 can be reduced, and the material selection of the magnet 113 can be widened.

FIG. 2 is an enlarged view of a bearing portion of a rotary shaft of a screw in an embodiment of the developing device of the present invention.

The developing device of the present embodiment has the same configuration as the developing device of the above-described reference example, but is characterized in that there is no step between the outer peripheral surface of the rotating shaft 102A of the screw 102 and the outer peripheral surface of the magnetic member 1. It is.

The rotating shaft 102A is a ring-shaped magnet 1
The portion from the portion substantially corresponding to 13 to the bearing 110 is thinned by the thickness of the magnetic member 1, and the hollow cylindrical magnetic member 1 is fitted and fixed to the portion, so that the rotating shaft There is no step on the outer peripheral surface between the magnetic member 1 and the portion of the developing container 104 from the inside of the developing container 104. According to this, the rubbing of the developer is caused by the magnetic member 1.
Concentration can be prevented, which is advantageous for rubbing by the developer. In other words, by eliminating the step, it is possible to eliminate the frictional resistance to the developer generated at the stepped portion when there is a step, thereby preventing the developer from entering the bearing without applying frictional heat to the developer. be able to.

The thickness of the magnetic member 1 can be freely selected by changing the diameter of the rotating shaft 102A, and the magnetic field from the magnet 113 concentrated on the magnetic member 1 can be adjusted to provide an appropriate sealing property. It is possible to set a magnetic field having the same. That is, when the outer diameter of the magnetic member 1 is constant, the rotation shaft 102A
By increasing the thickness of the magnetic member 1, the thickness of the magnetic member 1 is increased to increase the concentration of the magnetic field on the magnetic member 1, or conversely, the magnetic member 1
By making the rotating shaft 102A thicker under the constant outer diameter of
By reducing the thickness of the magnetic member 1, the degree of concentration of the magnetic field on the magnetic member 1 can be reduced, and thus the magnetic field can be controlled and set.

[0027]

[0028]

[0029]

[0030]

Although the screw 102b has been described above, the same applies to the screw 102a of the developer chamber 102a.

In the above embodiment, the hollow cylindrical magnetic member 1 is fixed to the rotating shaft 102A of the screw 102, and the ring-shaped magnet 113 is disposed at a position facing the hollow cylindrical magnetic member 1. May be fixed, and a ring-shaped magnetic member may be provided at a position facing the same, and the same effect can be obtained.

The present invention also relates to a developer conveying screw 102
It is needless to say that the present invention is not limited to a and 102b, and is equally effective with respect to a bearing portion of a rotating member installed in a container containing a developer of a developing device such as a developing roller and a developer stirring member. Absent.

[0034]

As described above, in the developing device of the present invention, the developer accommodating container accommodating the developer, the rotating member provided in the developer accommodating container, and the both ends of the rotating shaft of the rotating member are provided. A bearing portion, a cylindrical magnetic member provided on the outer peripheral surface near the end of the rotating shaft and inside the developer container relative to the bearing portion, and a cylinder provided so as to surround the magnetic member with a gap. And an outer peripheral surface of the magnetic member and a portion of the rotating shaft inside the developer accommodating container rather than the portion of the rotating shaft on which the magnetic member is provided, in which the step is eliminated. Therefore, (1) maintaining a high accuracy without affecting the rotation accuracy of the rotating member, and between the cylindrical magnet and the cylindrical magnetic member used for the magnetic seal of the developer in the bearing portion of the rotating member; Gap easily In particular, (2) when there is a step between the cylindrical magnet and the cylindrical magnetic member, frictional resistance to the developer generated at the stepped portion can be eliminated, so that frictional heat is not given to the developer, It is possible to prevent the developer from entering the bearing portion, to perform the magnetic sealing satisfactorily, and (3) to improve the assemblability and greatly improve the working efficiency. I can play.

Contrary to the above, a hollow cylindrical magnet is fixed to the outer peripheral surface of the rotating shaft of the rotating member, and a cylindrical magnetic member is disposed so as to surround the rotating magnet, thereby constituting a magnetic sealing mechanism. This also provides the same effects as described above.

[Brief description of the drawings]

FIG. 1 is an enlarged view showing a bearing portion of a rotary shaft of a screw in a reference example of a developing device of the present invention.

FIG. 2 is an enlarged view showing a bearing portion of a rotary shaft of a screw in one embodiment of the developing device of the present invention.

FIG. 3 is a configuration diagram illustrating a conventional developing device.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is an enlarged view of a portion B in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical magnetic member 102, 103 Screw 102A Rotating shaft 102b Magnetic shaft 104 Developing container 110 Bearing 113 Cylindrical magnet

Claims (2)

(57) [Claims] 1. A developer container for storing a developer, a rotating member provided in the developer container, a bearing for receiving both ends of a rotating shaft of the rotating member, and an end of the rotating shaft. A developing device comprising: a cylindrical magnetic member provided on the outer peripheral surface in the vicinity of the developer accommodating container relative to the bearing portion; and a cylindrical magnet provided so as to surround the magnetic member with a gap. In the apparatus, the step of eliminating the step between the outer peripheral surface of the magnetic member and the portion of the rotation shaft inside the developer accommodating container with respect to the portion of the rotation shaft provided with the magnetic member is eliminated. apparatus. 2. A developer accommodating container for accommodating a developer, a rotating member provided in the developer accommodating container, a bearing for receiving both ends of a rotating shaft of the rotating member, and an end of the rotating shaft. A cylindrical magnet provided on the outer peripheral surface in the vicinity of the developer accommodating container with respect to the bearing portion,
A developing device having the magnet and a cylindrical magnetic member provided so as to surround the magnet with a gap, wherein an outer peripheral surface of the magnet and a portion of the rotary shaft on which the magnet is provided are more inside the developer accommodating container. A developing device characterized in that a step is eliminated from the portion of the rotating shaft.