JP2002357217A - Seal unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfactorily prevent invasion of a developing agent to a bearing portion in an apparatus treating powder bodies such as an electronic photograph developing apparatus. SOLUTION: The developing agent is stored in a container of the developing agent, and a plurality of rotary members rotatably installed in the container of the developing agent via the bearing portion are further arranged in the container of the developing agent. A magnetic seal member 13 is arranged in the container in response to the bearing portion, and a second magnetic seal member 14 opposing to the first magnetic seal member is also arranged in the rotary member. Thus, the first and second magnetic seal members are opposed each other in different magnetic poles. Powder bodies are prevented from invading into the bearing portion by maintaining the powder bodies such as the developing agent and the like in lines of magnetic force (magnetic curtain) formed between a first and second magnet members. Namely, the bearing portion is magnetically shielded. The first and second magnetic seal members being magnetized bodies, even though the rotary member located in the vicinity of the first and second magnetic seal members is a magnetic member, the influence of these magnetic members is minimized, and thus, a magnetic field formed between the first and second magnetic seal members, namely, a magnetic curtain becomes stable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder processing apparatus comprising: a rotating member in which a magnetic powder is accommodated in a container and which is disposed in the container and rotatably attached to the container via a bearing. Regarding the sealing device used in the device,
In particular, the present invention relates to a sealing device for sealing a bearing portion from a developer in an electrophotographic developing device.

[0002]

2. Description of the Related Art Conventionally, electrophotography in which toner is selectively adhered to a positive latent image (in the case of normal development) or a negative latent image (in the case of reverse development) of a photosensitive drum or other image carrier to perform development. A developing device (dry electrophotographic developing device) is known. Dry development is classified into a one-component development method using only a toner as a developer and a two-component development method using a toner and a carrier, and is further classified according to the presence or absence of magnetism of the toner.

For example, a developing device using the two-component developing method is provided with a plurality of rotating members such as a developing roller, a stirring mechanism, and a toner replenishing roller, and these rotating members rotate to a developing container via a bearing. Mounted as possible. In this developing device, a new toner is supplied from a toner hopper to a developing container by a toner replenishing roller, and a mixture of the two-component developer in the developing container, the supplied toner, and the developer returned from the developing roller is stirred by a stirring mechanism. The toner and the carrier of the two-component developer are charged to electrostatically adhere the toner around the carrier. And
The toner is conveyed by the developing roller, and only the toner adheres to the electrostatic latent image on the photoconductor. The residual toner and carrier remaining on the developing roller are returned to the developing container, stirred again, and reused.

[0004] Developers used in the above-described developing devices generally have extremely small particle diameters, and these developers easily enter the bearings of the above-mentioned rotating members. Then, when the developer enters the bearing portion, frictional wear occurs in the sliding portion of the bearing portion, and the developer often aggregates. As a result, torque increases in the bearing portion. become.

In order to prevent such an increase in torque, a sponge or the like is interposed as a seal member between the developing container and the rotating member so as to fill a sliding surface (attachment portion) between the developing container and the rotating member. It has been practiced to prevent the developer from entering the bearing portion. Further, the use of an oil seal or the like to prevent the developer from entering the bearing portion is also performed.

However, even if the above-mentioned seal member is used, the sealability of the seal member is often impaired due to aging and deterioration and abrasion, and once the seal member is damaged, the developer is removed from the gap. There is a risk of breakage of the developer and an increase in torque.

In order to prevent such a problem, for example, a method of generating a repulsive magnetic field and magnetically sealing the bearing with the repulsive magnetic field is known. In this method, a magnetic field spreading around the repulsive magnetic field is known. A magnetic field is generated only around the bearing portion to hold the carrier and the magnetic toner around the bearing portion to prevent developer from entering the bearing portion. Call).

Furthermore, in the sealing device described in Japanese Patent Application Laid-Open No. 5-134540, a magnet is arranged on a bearing portion supporting a rotating shaft, a magnetic plate is arranged on the rotating shaft, and the magnet and the magnetic plate are arranged. And a carrier seal is formed between them. The carrier seal prevents the toner component from entering the bearing. That is, in the sealing device described in JP-A-5-134540, a magnet is arranged on the developer container side, and a magnetic plate is arranged on the rotating member side, and the magnet and the magnetic plate are opposed to each other. Then, the carrier is held between the magnet and the magnetic plate to perform sealing (this example is hereinafter referred to as Conventional Example 2).

[0009]

By the way, in the case of the prior art 1, since the magnetic sealing is performed by using the repulsive magnetic field, the repulsive force by the magnetic field is greatly applied to the sealing surface, which causes an increase in torque.

Further, in the conventional examples 1 and 2, the arrangement of the magnetic poles for sealing is inevitably affected by other magnetic materials disposed in the developing device. In particular, when a developing roller including a fixed sleeve and a fixed magnet roller is used as a developing roller, the arrangement of magnetic poles for sealing may change due to the influence of the fixed magnet roller. As a result, for example, in the case of Conventional Example 2, the distribution of the carrier (and the magnetic toner) held between the magnetic plate and the magnet becomes uneven, and a sufficient sealing effect may not be obtained. It has been confirmed that there is.

Further, in the case of the stirring roller used in the stirring mechanism, as the pressure of the developer moves with the rotation of the stirring roller, the developer and / or the magnetic toner held by the magnetic seal or the carrier seal are moved. Is disturbed, thereby causing a problem that the sealing performance is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sealing device capable of favorably preventing a developer from entering a bearing in an apparatus for handling powder, for example, an electrophotographic developing apparatus.

[0013]

According to the present invention, a magnetic powder (for example, a developer) is contained in a container and is disposed in the container and is rotatable via a bearing in the container. A seal device used in a powder processing device (for example, an electrophotographic developing device) having a rotating member attached to the seal member and used to seal the bearing portion from the powder, and corresponds to the bearing portion. A first magnet member arranged on the container side, and a second magnet member arranged on the rotating member side and facing the first magnet member,
A seal device characterized in that the first and second magnet members face each other with different magnetic poles is obtained, and the magnetic force lines (magnetic curtains) formed between the first and second magnet members are powdered. Hold the body to prevent powder from entering the bearing (ie, magnetically seal the bearing).

By arranging the first magnet member on the container side and the second magnet member on the rotating member side in this manner, the lines of magnetic force (magnetic field) formed between the first and second magnet members are formed. The curtain) holds the powder and magnetically seals the bearing part to prevent the powder from entering the bearing part. For example, if the sliding part such as the bearing part is buried in powder such as developer, Also, powder such as toner does not enter the bearing portion, and as a result, aggregation of toner and the like can be prevented.
For this reason, according to the present invention, it is possible to avoid an increase in torque, locking of the machine, and the like.

The first and second magnet members face each other at a predetermined interval. For example, the predetermined interval is in a range from 1 mm to 5 mm.

In the present invention, the first and second magnet members may be coaxially supported with the rotating member, and the first and second magnet members may be rotated together with the rotating member. The first and second magnets may be supported coaxially with the rotating member so that one of the first and second magnet members is rotatable with respect to the rotating member. In this case, it is desirable that the second magnet member be rotatable with respect to the rotating member.

By doing so, not only can the most stable magnetic seal be easily obtained, but also when the most stable magnetic seal state is deviated, the magnetic seal member arranged on the rotating member side can be used. It can easily return to the original optimal magnetic sealing state by rotating.For example, even if the sliding part such as the bearing is buried in the powder such as the developer, the powder such as the toner may enter the bearing. As a result, aggregation of toner and the like can be prevented. For this reason, as described above, it is possible to avoid an increase in torque and locking of the machine.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the illustrated examples are not intended to limit the scope of the present invention, but are merely illustrative examples, unless otherwise specified. Absent.

First, an example of a developing device will be described with reference to FIG. The illustrated developing device includes a developing container 1, which contains a developer (two-component developer) in which a carrier and a toner are mixed at a predetermined concentration ratio. The developing device has a developer carrier 2, and in the illustrated example, the developer carrier 2 is a rotating developing sleeve 2a and a fixed magnet roller (magnet assembly) contained in the rotating developing sleeve 2a.
2b, and the developing sleeve 2a is rotatably supported in the direction of the solid arrow S in the drawing. That is, the developing sleeve 2a is rotatably supported by the bearing. The developer carrier 2 faces the photosensitive drum 3 with a slight gap. As shown in the drawing, a doctor blade 4 is arranged opposite to the developing sleeve 2a, and the doctor blade 4
The layer thickness of the developer magnetically held thereon is regulated.

In the developing container 1, a cylindrical stirring member 5 is supported rotatably on the wall surface of the developing container in parallel with the axis of the developing sleeve 2a and is a single vibrating fin for conveying the developer. 6, a slit opening (not shown) is formed on one surface (left side in the figure) of the developing container 1, and a toner container (not shown) in which toner is stored in the developing container 1 through the slit opening. (Not shown) is detachably mounted.

Further, in the vicinity of the slit opening, for example, a toner supply roller 7 covered with a sponge is rotatably attached to the developing container 1 via a bearing portion. A motor is connected (not shown). A toner concentration detection sensor (not shown) is provided at the bottom of the developing container 1. The toner concentration detecting sensor detects the toner concentration in the developing container 1, that is, the toner (T) and the carrier ( C) and outputs a T / C detection signal. Then, a control unit (not shown) drives and controls the DC motor in accordance with the T / C detection signal to rotate the toner supply roller 7. As a result, the toner is supplied from the toner container into the developing container 1 through the slit opening by the toner supply roller 7. That is, a control unit (not shown) adjusts and controls the toner supply amount according to the T / C detection signal.

Here, an example of the stirring member will be described. The stirring member 5 is provided with a hollow cylinder 5a, which is rotated clockwise, for example, on the toner container side. It rotates from upper middle to lower.
A spiral carrier 5b is coaxially inserted through the hollow cylindrical body 5a, and the spiral carrier 5b is rotated counterclockwise. Further, a spiral projection 5 extends along the outer peripheral surface of the hollow cylindrical body 5a.
c are formed, and openings (not shown) are formed at predetermined intervals in the axial direction on the outer peripheral surface of the hollow cylindrical body 5a, and the hollow cylindrical body 5a and the spiral transport body 5b are rotated. Accordingly, uniform stirring and mixing of the developer are performed. Then, the developer on the developing sleeve 2a and the developer agitated and mixed by the agitating member 5 are mixed and agitated by the single vibration fin 6, and the developer on the developing sleeve 2a has a toner concentration equal to that of the developer in the developing container 1. Be uniform. That is, as shown by the flow arrow of the developer in FIG. 1, the flow of the developer is formed by the single vibration fin 6, and the toner concentration of the developer on the developing sleeve 2a and the developer in the developing container 1 is made uniform. .

On the other hand, the developer pumped up by the fixed magnet roller 2b in accordance with the rotation of the developing sleeve 2a has its layer thickness regulated by the doctor blade 4,
A predetermined developer layer is formed on the developing sleeve 2a. Then, the electrostatic latent image formed on the photosensitive drum 3 is developed by the developer on the developing sleeve 2a. Thereafter, the developer on the developing sleeve 2a is returned into the developing container 1 by the repulsive magnetic field of the fixed magnet roller 2b.

Referring now to FIG. 2, focusing on the stirring member 5, the stirring member 5 is rotatably supported on the developing container 1 by the bearing 11 as described above.
Specifically, the rotating shaft 12 of the stirring member 5 penetrates the developing container 1, and a bearing member 11 is provided in the penetrating portion, and the rotating shaft 12 is rotatably held. As shown, a ring-shaped first magnetic seal member (magnet member) 13 is disposed on the inner surface of the developing container 1, and a ring-shaped second magnetic seal member is provided on a side end surface of the stirring member 5. A (magnet member) 14 is provided, and the above-described rotary shaft 12 is provided at the center of the first and second magnetic seal members 13 and 14.
Is inserted. First and second magnetic seal members 13
And 14 face each other with a predetermined gap therebetween, and their facing surfaces have different magnetic poles.

Referring also to FIG. 3, as described above, the first and second magnetic seal members 13 and 14 have mutually opposite magnetic poles on their opposing surfaces. Numerous lines of magnetic force are formed between the members 13 and 14 (hereinafter these lines of magnetic force are referred to as magnetic curtains). With this magnetic curtain, the magnetic powder existing around the magnetic curtain is confined in the gap between the first and second magnetic seal members 13 and 14 along the lines of magnetic force.

Moreover, the first and second magnetic seal members 1
Since 3 and 14 are magnetic materials, even if the rotating members existing around the first and second magnetic seal members 13 and 14 are magnetic members, the influence is extremely small. as a result,
The magnetic field formed between the first and second magnetic seal members 13 and 14, that is, the magnetic curtain is stabilized. The distance between the first magnetic seal member 13 and the second magnetic seal member 14 (the predetermined gap described above) is 1 mm or more and 5 m or more.
m or less.

First and second magnetic seal members 13 and 1
Since the magnet 4 is a magnet, the magnitude of the magnetic field in the space between the two magnets is reduced by only about 10% every time the distance between the two is 1 mm. Since the magnitude of the magnetic field is inversely proportional to the square of the distance, it is possible to form a more stable magnetic field than a conventional magnetic plate that is induced by the magnitude of the magnetic field to form the opposite pole. As a result of the experiment, if the magnetic force of the first and second magnetic seal members 13 and 14 is 400 gauss or more, the interval between the seal members is 1 mm or more and 5 mm or less, and there is no problem, and it is confirmed that the magnetic curtain is extremely stable. Was.

The first and second magnetic seal members 13
When the magnetic force was 400 gauss or more, there was no difference in the rotation speed between 50 and 180 rpm. Also, since the sealing member is formed of a magnet, the diameter required to obtain a sealing effect is 12 mm for a 400 Gauss magnet.
As described above, if the magnet is 600 gauss, the thickness is 8 mm or more, so that the design flexibility is very large, and a design that can obtain a sufficient sealing effect with a small-diameter sealing member is possible.

In the example shown in FIG. 2, only one end of the stirring member 5 is shown, but it goes without saying that a magnetic seal member is similarly provided at the other end.

In the example shown in FIG. 2, the first and second magnetic seal members 13 and 14 are fixedly arranged on the inner surface of the developing container 1 and the side end surface of the stirring member 5, respectively. As shown in FIG. 1A, protrusions 12a and 12b extending in the radial direction are formed on the rotating shaft 12 at a predetermined interval, and protrusions 12a and 12a are formed on the inner peripheral surfaces of the first and second magnetic seal members 13 and 14, respectively. And 12b are formed with engagement portions 13a and 14a into which engagement portions 13a are fitted.
When the projections 12a and 12b are engaged with the first and second magnetic seal members 13 and 14, the first and second magnetic seal members 13 and 14 rotate according to the rotation of the rotary shaft 12.

Further, the first and second magnetic seal members 1
Only one of 3 and 14 may be arranged to be rotatable with respect to the rotating shaft 12. For example, as shown in FIG. 4B, the first magnetic seal member 13 is fixed to the inner surface of the developing container 1, and the second magnetic seal member 14 is separated from the first magnetic seal member 14 by a predetermined distance. In such a manner as to be rotatable with respect to the rotating shaft 12. At this time, in order to prevent the second magnetic seal member 14 from moving in the axial direction, the rotating shaft 1
2 includes a pair of ring-shaped movement preventing protrusions 21a and 21.
b is formed.

When only one of the first and second magnetic seal members 13 and 14 is disposed so as to be rotatable with respect to the rotary shaft 12 as described above, the second magnetic seal member 13 and the second magnetic seal member 13 are preferably disposed on the stirring member 5 side.
When the second seal member 14 faces the first seal member 13 for the first time including the time of assembling the developing device, the first seal member 14 is rotatably arranged with respect to the rotation shaft 12. And the second magnetic seal members 13 and 14 are attracted (or repelled), the second magnetic seal member 14 rotates, and the first and second magnetic seal members 13 and 14 attract each other most stably. Positional relationship. As a result, the first
Also, the magnetic field distribution (that is, the magnetic curtain) between the second magnetic seal members 13 and 14 becomes dense, and the distribution of the powder held by the magnetic curtain can be made the most stable distribution.

As described above, the second magnetic seal member 14
Is arranged rotatably with respect to the rotation shaft 12, the second
Since the magnetic seal member 14 does not rotate with the rotating shaft 12, the most stable magnetic field distribution can be maintained, and as a result, the optimum sealing effect is maintained.

Further, as shown in FIG. 4C, the height of the movement preventing protrusions 21a and 21b may be changed. For example, the height (protruding amount in the radial direction) of the movement prevention protrusion 21b located on the stirring member 5 side is set lower than the height of the movement prevention protrusion 21a located on the developer container 1 side. By making the heights of the movement preventing protrusions 21a and 21b different from each other, the frictional force applied to the second magnetic seal member 14 is different between the movement preventing protrusion 21a and the movement prevention protrusion 21b. Become. As a result, when a repulsive force is generated between the first and second magnetic seal members 13 and 14 by deviating from the state where the magnetic distribution is most stable, the frictional force that hinders the rotation of the second magnetic seal member 14 is substantially reduced. As a result, the second magnetic seal member 14 rotates again to a state where the magnetic distribution is most stable.

In the example shown in FIG. 4C, the first magnetic seal member 13 is fixed to the inner surface of the developing container 1, but as described with reference to FIG. The magnetic seal member 13 may be rotated together with the rotating shaft 12, and in this case also, when the magnetic distribution deviates from the most stable state, the second magnetic seal member 14 rotates and again. Return to stable position.

In the above description, an example in which the bearing portion of the stirring member is magnetically sealed has been described. However, the other rotating members of the developing device may be similarly configured such that the magnetic poles of the pair of magnetic sealing members have different magnetic poles. If you place it facing
Similarly, the bearing member can be magnetically sealed. Further, in an apparatus other than the developing apparatus, a magnetic seal can be performed in the same manner as long as the apparatus is provided with a rotatable member rotatably supported by a bearing portion in a case such as a container and processes powder.

[0037]

As described above, according to the present invention,
The bearing of the rotating member, which is a component of the developing device, can be magnetically sealed well.For example, even if the sliding part such as the bearing is buried in the powder of the developer, the bearing is magnetically sealed well. Therefore, powder such as toner does not enter the bearing portion, and as a result, aggregation of toner and the like can be prevented. For this reason, according to the present invention, it is possible to avoid an increase in torque, locking of the machine, and the like.

Further, in the present invention, since the magnetic seal member disposed on the rotating member side is arranged rotatably with respect to the rotating member, not only the most stable magnetic seal can be easily obtained, but also the magnetic seal member can be easily obtained. On the other hand, when the magnetic seal state deviates from the most stable magnetic seal state, the magnetic seal member disposed on the rotating member side is rotated to easily return to the original optimum magnetic seal state.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing an example of a developing device in which a sealing device according to the present invention is used;

FIG. 2 is a view for explaining a first example of a sealing device according to the present invention.

FIG. 3 is a diagram for explaining a magnetic sealing effect by the sealing device shown in FIG. 2;

4A and 4B are views for explaining another example of the sealing device according to the present invention, wherein FIG. 4A is a view showing a second example, FIG. 4B is a view showing a third example, and FIG. It is a figure showing the 4th example.

[Description of Signs] 1 Developing container 2 Developer carrier 2a Rotating developing sleeve 2b Fixed magnet roller (magnet assembly) 3 Photoconductor drum 4 Doctor blade 5 Stirrer 5a Hollow cylinder 5b Spiral carrier 5c Spiral protrusion 6 Simple vibration fin 7 Toner supply roller 11 Bearing 12 Rotary shaft 12a, 12b Projection 13, 14 Magnetic seal member 13a, 14a Engagement 21a, 21b Move prevention projection

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H077 AB02 AB03 AB14 AB15 AB18 AC02 AC03 CA13 CA15 EA03 FA19 3J103 CA01 DA01 FA22 FA26 GA54 GA57 HA06 HA08

Claims (7)

[Claims] 1. A powder processing apparatus comprising: a container containing magnetic powder in a container and a rotating member disposed in the container and rotatably attached to the container via a bearing. A sealing device used when sealing the bearing portion from the powder, a first magnet member disposed on the container side corresponding to the bearing portion,
A second magnet member disposed on the rotating member side and facing the first magnet member, wherein the first and second magnet members face each other with different magnetic poles. apparatus. 2. The apparatus according to claim 1, wherein the first magnet member disposed on the container side and the second magnet member disposed on the rotating member side face each other at a predetermined interval. Item 2. The sealing device according to Item 1. 3. The apparatus according to claim 2, wherein the first and second magnet members are supported coaxially with the rotating member, and the first and second magnet members rotate together with the rotating member. Item 3. The sealing device according to item 1 or 2. 4. The first and second magnet members are supported coaxially with the rotating member, and one of the first and second magnet members is rotatable with respect to the rotating member. The sealing device according to claim 1, wherein: 5. The sealing device according to claim 4, wherein the second magnet member is rotatable with respect to the rotating member. 6. The sealing device according to claim 1, wherein the powder processing device is an electrophotographic developing device. 7. The predetermined interval is not less than 1 mm and not more than 5 mm.
The sealing device according to claim 2, wherein the diameter is not more than mm.