JP4295929B2 - Sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device used in a powder processing apparatus in which a magnetic powder is contained in a container and a rotating member disposed in the container and rotatably attached to the container via a bearing portion. In particular, the present invention relates to a sealing device for sealing a bearing portion from a developer in an electrophotographic developing device.
[0002]
[Prior art]
Conventionally, an electrophotographic developing device (dry-type electrophotographic developing device) that performs development by selectively attaching toner to a positive latent image (in the case of normal development) or a negative latent image (in the case of reversal development) of a photosensitive drum or other image carrier. A photographic developing apparatus) is known. The dry development is classified into a one-component development method using only toner as a developer and a two-component development method using toner and carrier, and further classified according to the presence or absence of toner magnetism.
[0003]
For example, a developing device using a two-component development method includes a plurality of rotating members such as a developing roller, a stirring mechanism, and a toner replenishing roller, and these rotating members are rotatably attached to the developing container via a bearing portion. It has been. In this developing device, while the toner is newly replenished from the toner hopper to the developing container by the toner replenishing roller, the mixing of the two-component developer in the developing container, the replenished toner, and the developer returned from the developing roller is stirred. The toner of the two-component developer and the toner are charged to electrostatically adhere the toner around the carrier. Then, the toner is conveyed by a developing roller, and only the toner is attached to the electrostatic latent image on the photosensitive member. Residual toner and carrier remaining on the developing roller are returned to the developing container, and stirred again and reused.
[0004]
By the way, the developer used in the developing device as described above generally has a very small particle size, and these developers tend to enter the bearing portion of the rotating member. When the developer enters the bearing portion, friction due to friction occurs at the sliding portion of the bearing portion, and the developer often aggregates. As a result, the torque increases at the bearing portion. become.
[0005]
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 the sliding surface (attachment portion) between the developing container and the rotating member, and the bearing portion. It has been practiced to prevent the developer from entering the printer. Furthermore, it is also practiced to prevent the developer from entering the bearing using an oil seal or the like.
[0006]
However, even when a seal member such as that described above is used, the sealability of the seal member is often impaired due to aging and deterioration, and once the seal member is damaged, the developer enters from the gap. There is a risk of cracking of the developer and an increase in torque.
[0007]
In order to prevent such inconvenience, for example, a method of generating a repelling magnetic field and magnetically sealing the bearing portion by the repelling magnetic field is known. The magnetic field is generated only in the vicinity of the bearing and the carrier and the magnetic toner are held around the bearing portion to prevent the intrusion of the developer into the bearing portion (this example is hereinafter referred to as Conventional Example 1).
[0008]
Further, in the sealing device described in Japanese Patent Application Laid-Open No. 5-134540, a magnet is disposed on a bearing portion that supports a rotating shaft, a magnetic plate is disposed on the rotating shaft, and a gap between the magnet and the magnetic plate is disposed. The carrier is held to form a carrier seal. The carrier seal prevents the toner component from entering the bearing portion. That is, in the sealing device described in JP-A-5-134540, a magnet is disposed on the developing container side, a magnetic plate is disposed on the rotating member side, and the magnet and the magnetic plate are opposed to each other. The carrier is held between the magnet and the magnetic plate for sealing (hereinafter, this example is referred to as Conventional Example 2).
[0009]
[Problems to be solved by the invention]
By the way, in the case of the prior art example 1, since the magnetic seal is performed using the repulsive magnetic field, the repulsive force due to the magnetic field is greatly applied to the seal surface and causes a torque increase.
[0010]
Further, in the conventional examples 1 and 2, the magnetic pole arrangement for sealing is inevitably influenced by other magnetic bodies arranged in the developing device. In particular, when a developing roller in which a fixed magnet roller is included in a developing sleeve is used, the magnetic pole arrangement for the seal 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 magnetic toner) held between the magnetic material plate and the magnet becomes non-uniform, and a sufficient sealing effect may not be obtained. It has been confirmed that there is.
[0011]
Further, in the case of the stirring roller used in the stirring mechanism, the developer pressure moves as the stirring roller rotates, and as a result, the distribution of the developer and / or magnetic toner held by the magnetic seal or carrier seal is reduced. There is a problem in that the sealing performance deteriorates due to disturbance.
[0012]
An object of the present invention is to provide a sealing device capable of satisfactorily preventing the intrusion of a developer into a bearing portion in an apparatus for handling powder, for example, an electrophotographic developing apparatus.
[0013]
[Means for solving the problems]
According to the present invention, a magnetic powder (for example, developer) is accommodated in the container, and the rotating member is disposed in the container and rotatably attached to the container via a bearing portion. A sealing device used in a powder processing apparatus (for example, an electrophotographic developing device) for sealing the bearing portion from the powder, and is a first device disposed on the container side corresponding to the bearing portion. 1 magnet member and a second magnet member disposed on the rotating member side and facing the first magnet member, the first and second magnet members facing each other with different magnetic poles ,
Furthermore, 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. The powder is held by a magnetic force line (magnetic curtain) formed between the first and second magnet members to prevent the powder from entering the bearing portion (that is, the bearing portion is magnetically sealed). .
[0014]
Thus, by arranging the first magnet member on the container side and the second magnet member on the rotating member side, the lines of magnetic force (magnetic curtain) formed between the first and second magnet members are reduced. The bearing is magnetically sealed by holding the powder and prevents the powder from entering the bearing. For example, even if the sliding part such as the bearing is buried in the powder of the developer, etc. Thus, toner or the like powder does not enter, and as a result, aggregation of the toner or the like can be prevented. For this reason, in the present invention, it is possible to avoid an increase in torque, a machine lock, and the like.
[0015]
The first and second magnet members are opposed to each other with a predetermined interval. For example, the predetermined interval is in a range of 1 mm to 5 mm.
[0016]
The present invention is also used in a powder processing apparatus in which a magnetic powder is contained in a container, and a rotating member disposed in the container and rotatably attached to the container via a bearing portion. A sealing device used for sealing the bearing portion from the powder, the first magnet member disposed on the container side corresponding to the bearing portion, and the first magnet member disposed on the rotating member side. A first magnet member and a second magnet member facing each other, the first and second magnet members facing each other with different magnetic poles ,
Further, the first and second magnet members are supported coaxially with the rotating member, and the second magnet member is rotatable with respect to the rotating member .
[0017]
In this way, not only can the most stable magnetic seal be easily obtained, but also when the magnetic seal member arranged on the rotating member side rotates when it deviates from the most stable magnetic seal state. It is easy to return to the original optimum magnetic seal state.For example, even if the sliding part such as the bearing part is buried in the powder such as developer, the powder such as toner does not enter the bearing part. As a result, aggregation of toner and the like can be prevented. For this reason, as described above, it is possible to avoid a torque increase, a machine lock, and the like.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, etc. 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.
[0019]
First, with reference to FIG. 1, an example of a developing device will be described as an apparatus for handling powder. The illustrated developing device includes a developing container 1, and the developing container 1 contains a developer (two-component developer) in which a carrier and toner are mixed at a predetermined concentration ratio. The developing device includes a developer carrying member 2. In the illustrated example, the developer carrying member 2 includes a rotating developing sleeve 2 a and a fixed magnet roller (magnet assembly) 2 b included in the rotating developing sleeve 2 a. The developing sleeve 2a is rotatably supported in the direction of the solid line arrow S in the figure. That is, the developing sleeve 2a is rotatably supported by the bearing portion. The developer carrier 2 faces the photosensitive drum 3 with a slight gap. As shown in the figure, a doctor blade 4 is disposed so as to face the developing sleeve 2a, and the layer thickness of the developer magnetically held on the developing sleeve 2a is regulated by the doctor blade 4.
[0020]
In the developing container 1, a cylindrical stirring member 5 is rotatably supported by being supported by the wall surface of the developing container in parallel with the axis of the developing sleeve 2 a and a single vibrating fin 6 for transporting the developer is disposed. A slit opening (not shown) is formed on one surface (left side in the drawing) 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. ) Is detachably mounted.
[0021]
Further, in the vicinity of the slit opening, for example, a toner replenishing roller 7 covered with a sponge is rotatably attached to the developing container 1 via a bearing portion, and a DC motor is connected to the toner replenishing roller 7. (Not shown). A toner concentration detection sensor (not shown) is disposed at the bottom of the developing container 1, and this toner concentration detection sensor detects the toner concentration in the developing container 1, that is, toner (T) and carrier ( C) and a T / C detection signal is output. 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. Thus, the toner is replenished from the toner container into the developing container 1 through the slit opening by the toner replenishing roller 7. That is, the control unit (not shown) adjusts and controls the toner replenishment amount according to the T / C detection signal.
[0022]
Here, an example of the stirring member will be described. The stirring member 5 includes a hollow cylinder 5a. The hollow cylinder 5a is rotated clockwise, for example, on the toner container side from above in the drawing. Rotates downward. A spiral transport body 5b is coaxially inserted in the hollow cylinder 5a, and the spiral transport body 5b is rotated counterclockwise. Furthermore, a spiral projection 5c is formed along the outer peripheral surface of the hollow cylinder 5a, and openings (not shown) are formed at predetermined intervals in the axial direction on the outer peripheral surface of the hollow cylinder 5a. The developer is uniformly stirred and mixed according to the rotation of the hollow cylinder 5a and the spiral conveyance body 5b. Then, the developer on the developing sleeve 2a and the developer stirred and mixed by the stirring member 5 are mixed and stirred 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. It is assumed to be uniform. That is, as indicated by the flow arrow of the agent in FIG. 1, a developer flow 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. .
[0023]
On the other hand, the developer pumped up by the fixed magnet roller 2b according to the rotation of the developing sleeve 2a has its layer thickness regulated by the doctor blade 4, and 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.
[0024]
Here, referring to FIG. 2, focusing attention on the stirring member 5, the stirring member 5 is rotatably supported by the developing container 1 by the bearing portion 11 as described above. Specifically, the rotating shaft 12 of the stirring member 5 passes through the developing container 1, and a bearing member 11 is disposed in the penetrating portion, and the rotating shaft 12 is rotatably held. As illustrated, 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 disposed on the side end surface of the stirring member 5. A (magnet member) 14 is disposed, and the above-described rotating shaft 12 is inserted through the central portions of the first and second magnetic seal members 13 and 14. The first and second magnetic seal members 13 and 14 are opposed to each other with a predetermined gap, and the opposed surfaces have different magnetic poles.
[0025]
Referring also to FIG. 3, as described above, since the first and second magnetic seal members 13 and 14 have different magnetic poles on their opposing surfaces, the first and second magnetic seal members 13 and 14 A number of magnetic field lines are formed between 14 (hereinafter these magnetic field lines are referred to as a magnetic curtain). Due to this magnetic curtain, the magnetic powder present in the vicinity of the magnetic curtain is restrained in the gap between the first and second magnetic seal members 13 and 14 along the lines of magnetic force.
[0026]
In addition, since the first and second magnetic seal members 13 and 14 are magnetic bodies, even if the rotating member existing around the first and second magnetic seal members 13 and 14 is a magnetic member, the influence thereof. Are very few. 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 above-mentioned predetermined gap) is preferably 1 mm or more and 5 mm or less.
[0027]
Since the first and second magnetic seal members 13 and 14 are magnets, the magnitude of the magnetic field in the space sandwiched between both magnets decreases 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 than the counter pole. As a result of the experiment, if the magnetic force of the first and second magnetic seal members 13 and 14 is set to 400 gauss or more, it is confirmed that the interval between the seal members is 1 mm to 5 mm and there is no problem and the magnetic curtain is extremely stable. It was.
[0028]
Moreover, when the 1st and 2nd magnetic seal members 13 and 14 were rotated with the rotating shaft 12, and it confirmed, if magnetic force was 400 gauss or more, there was no difference between 50-180 rpm about rotational speed. In addition, since the seal member is formed of a magnet, the diameter required to obtain the sealing effect is 12 mm or more for a 400 gauss magnet, and 8 mm or more for a 600 gauss magnet, which gives a great degree of design freedom. A large and small-diameter seal member can be designed to obtain a sufficient sealing effect.
[0029]
In the example shown in FIG. 2, only one end portion of the stirring member 5 is shown, but it goes without saying that the magnetic seal member is similarly disposed at the other end portion.
[0030]
In the example shown in FIG. 2, an example in which the first and second magnetic seal members 13 and 14 are fixedly disposed on the inner side surface of the developing container 1 and the side end surface of the stirring member 5 has been described, but FIG. As shown, protrusions 12a and 12b extending in the radial direction are formed on the rotary shaft 12 at a predetermined interval, and protrusions 12a and 12b are formed on the inner peripheral surfaces of the first and second magnetic seal members 13 and 14, respectively. When the engaging portions 13a and 14a to be fitted are formed and the protrusions 12a and 12b are engaged with the engaging portions 13a and 14a, the first and second magnetic seal members 13 and 14 rotate the rotation shaft 12. It will rotate according to.
[0031]
Furthermore, only one of the first and second magnetic seal members 13 and 14 may be disposed so as 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 spaced from the first magnetic seal member 14 at a predetermined interval. It arrange | positions so that rotation with respect to the rotating shaft 12 is possible. At this time, in order to prevent the second magnetic seal member 14 from moving in the axial direction, a pair of ring-shaped movement preventing protrusions 21a and 21b are formed on the rotating shaft 12.
[0032]
As described above, 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 rotating shaft 12, the second magnetic seal member 14 disposed on the stirring member 5 side is particularly provided. When the second seal member 14 is opposed to the first seal member 13 for the first time, including when the developing device is assembled, the first and second magnetic seals are arranged so as to be rotatable with respect to the rotary shaft 12. The members 13 and 14 are attracted (or repelled), the second magnetic seal member 14 is rotated, and the first and second magnetic seal members 13 and 14 are most stably attracted to each other. As a result, the magnetic field distribution (that is, the magnetic curtain) between the first and second magnetic seal members 13 and 14 becomes dense, and the distribution of the powder held by the magnetic curtain can be the most stable distribution. .
[0033]
As described above, when the second magnetic seal member 14 is disposed so as to be rotatable with respect to the rotary shaft 12, the second magnetic seal member 14 does not rotate together with the rotary shaft 12. The magnetic field distribution can be maintained, and as a result, the optimum sealing effect is maintained.
[0034]
Furthermore, as shown in FIG. 4C, the heights of the movement preventing protrusions 21a and 21b may be changed. For example, the height (the protruding amount in the radial direction) of the movement preventing protrusion 21b located on the stirring member 5 side is set lower than the height of the movement preventing protrusion 21a located on the developing container 1 side. Thus, by making the heights of the movement preventing protrusions 21a and 21b different, the frictional force applied to the second magnetic seal member 14 is different between the movement preventing protrusion 21a and the movement preventing protrusion 21b. Become. As a result, when a repulsive force is generated between the first and second magnetic seal members 13 and 14 when the magnetic distribution deviates from the most stable state, a frictional force that hinders the rotation of the second magnetic seal member 14 is substantially generated. Accordingly, the second magnetic seal member 14 is rotated again to a state where the magnetic distribution is most stable.
[0035]
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 in FIG. 4A, the first magnetic seal member In this case, when the magnetic distribution deviates from the most stable state, the second magnetic seal member 14 rotates and becomes a stable position again. Return to.
[0036]
In the above description, the example in which the bearing portion of the stirring member is magnetically sealed has been described. However, in the same manner for other rotating members of the developing device, the pair of magnetic seal members are opposed to each other so that their magnetic poles are different from each other. In the same manner, the bearing member can be magnetically sealed.
Furthermore, in devices other than the developing device, magnetic sealing can be performed in the same manner as long as the device is provided with a rotating member rotatably supported by a bearing portion in a case such as a container and processes powder.
[0037]
【The invention's effect】
As described above, according to the present invention, it is possible to satisfactorily magnetically seal the bearing of the rotating member that is a component of the developing device. For example, the sliding portion such as the bearing portion is provided on the powder of the developer or the like. Even if the bearing is buried, the bearing is well magnetically sealed, so that powder such as toner does not enter the bearing, and as a result, aggregation of the toner or the like can be prevented. For this reason, in the present invention, it is possible to avoid an increase in torque, a machine lock, and the like.
[0038]
In the present invention, since the magnetic seal member arranged on the rotating member side is arranged to be rotatable with respect to the rotating member, not only the most stable magnetic seal can be easily obtained but also the most stable When deviating from the magnetic seal state, the magnetic seal member disposed on the rotating member side is rotated, so that the original optimum magnetic seal state can be easily restored.
[Brief description of the drawings]
FIG. 1 is a perspective view schematically showing a partially broken 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 view for explaining a magnetic sealing effect by the sealing device shown in FIG. 2;
4A and 4B are diagrams for explaining another example of the sealing device according to the present invention, in which FIG. 4A is a diagram showing a second example, FIG. 4B is a diagram showing a third example, and FIG. It is a figure which shows the 4th example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Developer container 2 Developer carrier 2a Rotating developing sleeve 2b Fixed magnet roller (magnet assembly)
3 Photosensitive drum 4 Doctor blade 5 Stirring member 5a Hollow cylinder 5b Spiral carrier 5c Spiral protrusion 6 Single vibration fin 7 Toner supply roller 11 Bearing 12 Rotating shaft 12a, 12b Protrusion 13, 14 Magnetic seal members 13a, 14a Engagement part 21a, 21b Movement prevention protrusion part

Claims (6)

A magnetic powder is contained in a container, and is used in a powder processing apparatus having a rotating member disposed in the container and rotatably attached to the container via a bearing portion. A sealing device used when sealing a bearing portion, the first magnet member disposed on the container side corresponding to the bearing portion, and the first magnet member disposed on the rotating member side A second magnet member facing each other, the first and second magnet members facing each other with different magnetic poles ,
Furthermore, 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 .   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. Sealing device.   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. A magnetic powder is contained in a container, and is used in a powder processing apparatus having a rotating member disposed in the container and rotatably attached to the container via a bearing portion. A sealing device used when sealing a bearing portion, the first magnet member disposed on the container side corresponding to the bearing portion, and the first magnet member disposed on the rotating member side A second magnet member facing each other, the first and second magnet members facing each other with different magnetic poles ,
Further, the first and second magnet members are supported coaxially with the rotating member, and the second magnet member is rotatable with respect to the rotating member . The powder processing apparatus, the sealing apparatus according to any one of claims 1 to 4, characterized in that an electrophotographic developing apparatus.   The sealing device according to claim 2, wherein the predetermined interval is 1 mm or more and 5 mm or less.

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