JPH11338246A - Developing device, process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make slip out of the developer in the developing sleeve lengthwise direction, and leak of the developer corresponding to the impact so as possible to be restrained/prevented. SOLUTION: This developing device is, allowed to increase magnetic flux density on the developing sleeve 31 surface position by arranging magnetic sealing members 34 consisting of at least two magnets 34a and 34b in the lengthwise direction on the developing sleeve 31 so that opposing surface is respectively becoming to the same polarity, on both end parts of the developing sleeve 31, with a specified gap (g) between a periphery of the developing sleeve 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image using electrophotography, such as a copying machine, a printer, a facsimile, and a word processor, and more particularly, to a magnetic developer or a magnetic particle as a developer. TECHNICAL FIELD The present invention relates to a developing device using a two-component developer composed of a developer and a non-magnetic developer, a process cartridge including the developing device, and an image forming apparatus.

A process cartridge is a device in which a developing device, a charging unit or a cleaning unit, and an image carrier are integrally formed into a cartridge, and this cartridge is detachable from an image forming apparatus main body. Or
It means that at least the developing device and the image carrier are integrally formed into a cartridge and can be attached to and detached from the image forming apparatus main body.

[0003]

2. Description of the Related Art Conventionally, an electrostatic latent image is formed on an image carrier such as an electrophotographic photoreceptor (hereinafter, referred to as a "photoreceptor"), and the latent image is developed with a developer to be visualized. An image forming apparatus using electrophotography, which includes a step of transferring a visible image onto a recording material and fixing the unfixed image after transfer to form a permanent image, will be understood with reference to FIG. A drum-shaped photoconductor as an image carrier, that is, the photoconductor drum 1, and among the devices arranged on the outer periphery of the photoconductor drum 1 and acting on the photoconductor 1, the photoconductor drum 1 is uniformly charged. Charging device 2, a developing device 3 for developing and developing an electrostatic latent image formed on the photosensitive drum 1, and a cleaning device 5 for cleaning the photosensitive drum 1 after transferring the toner image to the recording material P. Is a process cartridge 10 integrally formed as a cartridge. There is a process cartridge type which is detachably mountable to scan cartridge 10 to the image forming apparatus main body. According to this method, the maintenance of the image forming apparatus can be performed by the user himself without relying on the serviceman, and the operability can be remarkably improved.
Therefore, this process cartridge system is widely used in image forming apparatuses.

An example of a conventional developing device 3 incorporated in the process cartridge 10 will be described in more detail with reference to FIGS. FIG. 15 is a front sectional view of the developing device, and FIG. 16 is a side sectional view of a main part of the developing device.

[0005] As shown in FIG. 15, the developing device 3 is provided with a developing sleeve 31 as a developer carrier, and has a magnet roller 32 therein. As can be clearly understood from FIG. It is rotatably supported by the developing container 30 via 35. The developer is the developer container 3
The developer supplied from the developing container 30 adheres to the surface of the developing sleeve 31 by the magnetic force of the magnet roller 32, and the developing blade 33 rotates with the rotation of the developing sleeve 31 in the arrow direction. Regulates the layer thickness to be constant. Thereafter, at a position facing the latent image on the photosensitive drum 1 built in the process cartridge similarly to the developing device, the developer adheres to the latent image with the rotation of the developing sleeve 31 to perform development.

Here, in the developing device 3, an elastic seal member 36 is provided at the both ends in the longitudinal direction outside the developing region of the developing sleeve 31, at a depth opposite to the opening of the developing device 3. This prevents the developer from flowing out of the developing area.

Conventionally, an elastic body such as felt or foamed rubber is widely used for the seal member as described above.
As shown in FIG. 16, the outflow of the developer is prevented by pressing the elastic sealing member 36 against the outer peripheral surface of the developing sleeve 31.

However, in the developing device having such a configuration,
An elastic seal member 36 is provided on half of the outer peripheral surface of the developing sleeve 31.
Are pressed against each other, so that the load on the rotating developing sleeve 31 is large during the developing operation.
There is a problem that the elastic seal member 36 is deteriorated due to the contact with the sealing member and the sealing performance is deteriorated. Further, a small amount of toner may enter between the developing sleeve 31 and the elastic seal member 36, and as a result, the torque increases, and the fluctuation of the torque increases to cause rotation unevenness. May adversely affect formation.

In order to solve such a problem, the developer is prevented from flowing out by arranging a magnet sealing member formed of a magnet at both ends of the developing sleeve 31 with a fixed gap without pressing. A way to do that has been proposed.

FIG. 17 is a front sectional view showing an example of a conventional developing device using a magnet sealing member. The magnet seal members 34 are wound around both ends of the developing sleeve 31 with a predetermined gap g therebetween with respect to the outer peripheral surface of the developing sleeve 31 having the magnet roller 32 therein. 30 is attached.

FIG. 18 is a schematic diagram showing a magnetized pattern in a conventional magnet seal member 34. As shown in FIG. As a conventional example,
Three examples of FIGS. 18 (a), (b) and (c) are shown. FIG.
In (a), the NS pole is magnetized into multiple magnetic poles on the inner peripheral surface. In FIG. 18B, the inner peripheral surface of the magnet seal member 34 is magnetized to one magnetic pole (S pole in the illustrated example), and the opposite surface is magnetized to a magnetic pole of a different polarity (N pole in the illustrated example). In FIG. 18C, the NS pole is formed on both sides sandwiching the inner peripheral surface of the magnet seal member 34.

When such a developer outflow prevention means is used, since the developing sleeve 31 and the magnet seal member 34 are not in contact with each other, the rotational torque of the developing sleeve 31 is extremely small, and therefore the drive motor is small and low. The developing sleeve 3 is inexpensive.
1 and uneven rotation of the photosensitive drum 1 are less likely to occur. Further, since the magnet seal member 34 is non-contact, it can be used semi-permanently without abrasion and can be recycled.

[0013]

However, in the conventional technique for preventing the developer from flowing out using the magnet seal member 34,
Since the relationship between the fixed magnet (magnet roller) 32 inside the developing sleeve and the magnet sealing member 34 is not sufficiently considered, depending on the use situation, for example, the developing device held on the developing sleeve 31 when the developing device is used. As the developing sleeve 31 rotates, the agent may move to the longitudinal end of the developing sleeve 31 and slip through the magnet seal member 34, which may cause a problem.

Accordingly, an object of the present invention is to further improve the technique of preventing the developer from flowing out using a magnet seal member, to suppress and prevent the developer from passing through the developer carrier in the longitudinal direction,
Another object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus that suppress or prevent developer leakage caused by impact or the like.

[0015]

The above object is achieved by a developing device, a process cartridge and an image forming apparatus according to the present invention. In summary, the present invention provides a developing container containing a magnetic developer or a two-component developer containing magnetic particles and a non-magnetic developer as a developer, and a magnet rotatably supported by the developing container and arranged inside. A developer carrying member for carrying and transporting the developer to the image carrier by carrying out the process, wherein the developer carrying member is provided at both ends of the developer carrying member. And a magnet seal member including at least two magnets is disposed at a predetermined gap from the outer peripheral surface of the developer carrier so that the opposing surfaces in the longitudinal direction of the developer carrier have magnetic poles of the same polarity.

According to another aspect of the present invention, in a process cartridge detachable from an image forming apparatus main body, a process having an image carrier and a developing device having at least a developer carrier acting on the image carrier is provided. Means, a magnet seal member comprising at least two magnets at both ends of the developer carrier with a predetermined gap from the outer peripheral surface of the developer carrier, and a surface facing the longitudinal direction of the developer carrier. Are arranged so as to be magnetic poles of the same polarity.

According to another aspect of the present invention, there is provided an image forming apparatus in which a process cartridge is detachable and which forms an image on a recording medium, comprising: (a) an image carrier; Process means having a developing device provided with a developer carrier; and a magnet seal comprising at least two magnets at both ends of the developer carrier with a predetermined gap from the outer peripheral surface of the developer carrier. Mounting means for removably mounting the process cartridge to the apparatus main body, wherein the member is arranged so that the opposing surfaces in the longitudinal direction of the developer carrier have magnetic poles of the same polarity; An image forming apparatus comprising: a conveying unit that conveys a recording medium.

According to one embodiment of the present invention, a magnetic member is disposed at least in a portion of the developer carrier that faces a region of the magnet seal member where magnetic poles of the same polarity face each other.

According to another embodiment of the present invention, at least two magnets of the magnet sealing member are arranged via a magnetic member such that opposite surfaces in the longitudinal direction have magnetic poles of the same polarity.

According to another embodiment of the present invention, at least two magnets of the magnet sealing member are arranged so as to be closely contacted in the longitudinal direction so that opposing surfaces have magnetic poles of the same polarity.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a developing device according to the present invention, and a process cartridge and an image forming apparatus provided with the same will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of a laser beam printer as an embodiment of an image forming apparatus using an electrophotography in which a process cartridge having a developing device according to the present invention is detachable. In the present embodiment, the present invention is applied to a laser beam printer as an image forming apparatus, but the present invention is not limited to this.

According to this embodiment, the laser beam printer has a drum-shaped photosensitive member as an image carrier at its center.
That is, the photosensitive drum 1 is provided. A roller charging device 2 as charging means is arranged around the photosensitive drum 1, and when the printer starts an image forming operation, the charging device 2 uniformly charges the surface of the photosensitive drum 1. Thereafter, the photosensitive drum 1 is image-exposed by a laser beam L emitted from the image exposing means E in accordance with the image information signal.
An electrostatic latent image is formed thereon. Next, the electrostatic latent image formed on the photosensitive drum 1 is developed by a developing device 3 arranged on the outer periphery of the photosensitive drum 1 to become a visible image. On the other hand, cassette 7
A recording material P, which is a recording medium accommodated in the printer, is fed by a feed roller 11 in synchronization with the formation of a latent image on the photosensitive drum 1. The sheet is conveyed to the transfer device 4 via the conveying unit 12 in synchronization.

Next, the visible image formed on the photosensitive drum 1 is
The image is transferred onto a recording material P fed from a cassette 7 by a transfer device 4 arranged on the outer periphery of the photosensitive drum 1. Thereafter, the unfixed image transferred onto the recording material P is fixed by a fixing device 6 such as a heat fixing method to be a permanent image. Thereafter, the surface of the photosensitive drum 1 is subjected to removal of attached contaminants such as residual toner by a blade cleaning device 5 as a cleaning unit disposed so as to be in contact with the surface.
After being cleaned, the photosensitive drum 1 is repeatedly used for image formation.

According to the present embodiment, the four process means of the photosensitive drum 1, the charging device 2, the developing device 3, and the cleaning device 5 are collectively attached to and detachable from the image forming apparatus main body as a process cartridge 10. is there. 4 above
One process is to place the cartridge housing 9 in place.
Incorporated in The process cartridge is mounted on the image forming apparatus main body so as to be held by the insertion / removal guide / holding section 8 as mounting means on the image forming apparatus main body side. When the process cartridge 10 is attached to the image forming apparatus main body in a predetermined manner, the process cartridge 10 side and the image forming apparatus main body side are mechanically and electrically coupled to each other. The lower surface of the photosensitive drum 1 comes into contact with the transfer device 4 on the image forming apparatus main body side in a predetermined manner, and an image forming execution state is set.

In this embodiment, as shown in FIG. 2, the process means of the photosensitive drum 1, the charging device 2, the developing device 3, and the cleaning device 5 are integrally formed as a process cartridge 10. However, the present invention is not limited to this. As described above, the process cartridge includes a developing device, a charging unit or a cleaning unit, and an image carrier integrally formed as a cartridge. The developing device and the image carrier can be integrated into a cartridge so that the developing device and the image carrier can be detachably mounted on the main body of the image forming apparatus.

Next, the developing device 3 will be described in more detail with reference to FIGS.

FIG. 3 is a central cross-sectional view of the developing device, FIG. 4 is a main cross-sectional view of a main part of the developing device, FIG. 5 is a perspective view of a developer carrier and a magnet seal member as developing means, and FIG. FIG. 6 shows a longitudinal sectional view of the portion, and FIG. 7 shows a magnetization pattern of the magnet seal member.

In this embodiment, a magnetic developer is used as a developer. However, it should be understood that the present invention can be applied to a case where a two-component developer composed of a non-magnetic developer and magnetic particles (carrier) is used. . The magnetic developer is stored in the developing container 30.

The developing device 3 is provided with a developing sleeve 31 made of a nonmagnetic cylinder such as aluminum or stainless steel as a developer carrier, and a magnet roller 32 is fixedly disposed inside the developing sleeve 31. The developing sleeve 31 is rotatably attached to the developing container 30 via a sleeve bearing. In the present embodiment, the magnet roller has two north poles N1 and N2 and two south poles S1 and S2 on the surface in the illustrated pattern. The developing sleeve 31 rotates in the direction shown by the arrow, and the magnetic toner supplied in the developing container 30 is adhered to the surface by the magnetic force of the magnet roller 32 and conveyed.

The developing device 3 further has a regulating blade 33 (developing blade) as a developing layer thickness regulating means.
This developing blade 33 is N
By pressing the developing sleeve 31 in the presence of the two poles, the thickness of the developer layer carried and transported by the developing sleeve 31 to the developing area is regulated. The carried and conveyed magnetic toner visualizes the latent image formed on the photosensitive drum 1 moving in the direction of the arrow in the developing area (developing magnetic pole S1). Developing sleeve 31
A power source (not shown) applies a vibration bias voltage obtained by superimposing a DC voltage on an AC voltage. Incidentally, a rectangular wave, a sine wave, or the like can be used as the waveform of the vibration bias voltage.

The residual toner after developing the latent image on the photosensitive drum 1 is collected into the developing container 30 at the take-in pole N1 at the entrance of the developing container 30, and is stirred with the magnetic toner in the developing container 30 via the pumping pole S2. Mixed.

In this embodiment, the peripheral speed of the photosensitive drum 1 is 94
mm / sec and the outer diameter is 30 mm.
Has a peripheral speed of 111 mm / sec and an outer diameter of 16 mm.
The rotation direction of the developing sleeve 31 was set to the forward direction with respect to the rotation direction of the photosensitive drum 1. Photosensitive drum 1 and developing sleeve 3
The distance from 1 was 0.3 mm.

According to this embodiment, the developing device 3 has the magnet seal members 34 at both ends in the longitudinal direction of the developing sleeve 31. The configuration of the magnet seal member 34 will be described in more detail.

As shown in FIG. 7, the magnet seal member 34 is a magnet seal member composed of magnets 34a and 34b having N and S poles magnetized on the side surfaces.
The N pole and the N pole are opposed to each other, and the opposite surfaces are S poles, and are arranged at both ends of the sleeve 31 as shown in FIG. This magnet seal member 34 is similar to that shown in FIGS.
As shown in (1), it is arranged with a gap g from the outer peripheral surface of the sleeve 31 and attached to the developing container 30. In this embodiment, as shown in FIGS. 5 and 6, the magnet seal member 34 is arranged in the longitudinal direction of the developing sleeve 31 such that the magnet 34 a has the S pole, N pole, and gap A, and the magnet 34 b has the N pole and S pole. In order.

FIG. 9 is a schematic diagram showing the state of the lines of magnetic force due to the arrangement of the magnetic poles of the magnet. FIG. 9A shows the case where the magnetic poles are arranged perpendicular to the developing sleeve 31, and FIG.
FIG. 9B shows a case where magnetic poles are arranged in parallel to the developing sleeve 31, and FIG. 9C shows a magnetic pole arrangement of this embodiment. In the present embodiment, two magnets are arranged so that each magnetic pole is parallel to the developing sleeve 31 and two magnets 34a, 3a
The magnetic poles are arranged so that the opposing surface of 4b has the same polarity as the N pole.

As shown in FIG. 9A, when the magnetic poles are arranged vertically, the lines of magnetic force are directed in the direction perpendicular to the developing sleeve 31, and the magnetic toner is arranged along the lines of magnetic force. Is considered to be good.

As shown in FIG. 9B, when the magnetic poles are arranged in parallel, the lines of magnetic force are parallel to the developing sleeve 31, and the magnetic toner is arranged along the lines of magnetic force. It is considered that the sealing property is inferior.

On the other hand, FIG.
When the magnetic poles of the two magnets 34a and 34b are arranged in parallel to the developing sleeve 31 and the opposite surfaces have the same polarity as shown in FIG.
By forming an N repulsive magnetic field, in this NN repulsive magnetic field,
The lines of magnetic force are directed perpendicular to the developing sleeve 31, and depending on the distance between the two magnets, the lines of magnetic force are more concentrated than in the case where the magnetic poles are arranged vertically as shown in FIG. 9A. Therefore, it is considered that the magnetic toner is arranged along the lines of magnetic force, so that the sealing property is further improved.
Even if a non-magnetic member is arranged between the two magnets 34a and 34b, the lines of magnetic force show the same shape.

In this embodiment, the magnet sealing member 34
Reference numerals a and 34b denote injection-molded products each having a width of 3 mm provided with a nylon binder containing Nd-Fe-B magnetic powder. The distance A between the magnet seal members 34a and 34b is 1 mm
And Spacing g between magnet seal member 34 and sleeve 31
Was set to 0.1 to 0.7 mm.

When the magnet seal member 34 is disposed at such a position, the magnetic flux in the direction normal to the surface of the developing sleeve on the surface of the developing sleeve 31 of each magnetic pole of the magnet roller 32 fixed in the developing sleeve 31 The peak value of the density was 400 to 900 × 10 ⁻⁴ T (tesla). At this time, the peak value of the magnetic flux density of each magnetic pole of the magnet seal member 34 on the surface of the developing sleeve 31 in the direction normal to the sleeve surface was 1000 to 2200 × 10 ⁻⁴ T (tesla). Therefore, as can be seen from the above measured values of the magnetic flux density, by adopting the configuration of the magnet seal member 34 in this embodiment, the magnitude of the magnetic force in the normal direction at the surface position of the developing sleeve 31 by the magnet seal member 34 alone is used. In all regions of the developer nip formed by the magnet seal member 34 with the developing sleeve 31, the magnitude of the magnetic force in the normal direction at the surface position of the developing sleeve 31 by the magnet alone inside the developing sleeve 31 is larger. It became possible to do.

Next, referring to FIG. 8, the state of the magnetic flux density at the surface position of the developing sleeve 31 due to the difference in the arrangement of the magnets of the magnet seal member 34 composed of two identical magnets will be described. FIG. 8A shows a case where the magnetic poles of the two magnets are arranged vertically and closely to the developing sleeve. FIG. 8B shows that the magnetic poles of the two magnets are
This is a case where the opposing surface is arranged so as to have the same polarity as the N pole and the magnetic pole is parallel to the developing sleeve. FIG. 8 (c) shows that the magnetic poles of the two magnets
This is a case where the poles are closely contacted to have the same polarity and the magnetic poles are arranged so as to be parallel to the developing sleeve. The dotted line in the figure indicates the surface position of the developing sleeve.

For each of these, the peak value of the magnetic flux density in the perpendicular direction at the surface position of the developing sleeve was measured. In the case of FIG. 8A, the peak value was 800 × 10 ⁻⁴ T (tesla). In the case of (a), it was 1200 × 10 ^-4 T (tesla), and in the case of FIG. 8 (c), it was 1400 × 10 ^-4 (tesla).

As can be seen from the above description, the magnet seal member composed of two magnets has the same polarity on the opposing surfaces of the magnets and the magnetic poles are parallel to the developing sleeve surface position. With this configuration, the repulsive magnetic fields of the two magnets can be used, and the peak value of the magnetic flux density in the vertical direction at the developing sleeve surface position can be increased.

Embodiment 2 FIG. 10 is a perspective view of a developer carrier (developing sleeve) 31 and a magnet seal member 34 in the developing device according to the present invention. FIG. 11 is a longitudinal sectional view of a main part of the developing device according to the present embodiment. In this embodiment, the developing sleeve 3
1 and the configuration of the magnet seal member 34 are different from those of the first embodiment,
The other configurations are essentially the same as those in the first embodiment, and a detailed description thereof will be omitted.

In the first embodiment, the two magnets 34a and 34b constituting the magnet sealing member 34 are arranged so that the N pole and the N pole face each other with the gap A therebetween. The magnetic member 34c is arranged at the position shown in FIG. Further, in the first embodiment, the developing sleeve 31 is formed only of the non-magnetic member. However, in the present embodiment, the magnetic member 31b is disposed at a portion facing the magnet seal member 34.

More specifically, in this embodiment, FIG.
As shown in FIG. 0 and FIG. 11, a magnet seal member 34 is formed by joining magnets 34a and 34b having N and S poles magnetized on their side surfaces via a magnetic member 34c such that the N and N poles face each other. It is a seal member, and is disposed at both ends in the longitudinal direction of the developing sleeve 31. In the present embodiment, the magnet seal member 34
The pole, the N pole, the magnetic member 34c, the N pole of the magnet 34b, and the S pole are in this order.

The developing sleeve 31 is made of a non-magnetic member 31.
a magnetic sleeve 31b, and a magnetic member 31b is disposed at a portion facing the magnet seal member 34.

With reference to FIG. 9, which is a schematic view showing the state of the lines of magnetic force, the arrangement of the lines of magnetic force in this embodiment will be described. FIG. 9C shows the configuration of the magnet seal member 34 according to the first embodiment. The two magnets 34 a and 34 b are arranged such that each magnetic pole is parallel to the developing sleeve 31 and two magnets 34 a , 34b are arranged with air gaps therebetween so that the opposing surfaces of N and N have the same polarity, and the developing sleeve 31 is composed of only a non-magnetic member. FIG.
(D) shows the configuration of the magnet seal member 34 of the present embodiment, in which two magnetic poles 34a and 34b are arranged so that their magnetic poles are parallel to the developing sleeve 31 and two magnets 34a and 34b.
A case is shown in which the opposite surface of the developing sleeve 31 is joined via a magnetic member 34c so that the opposing surface of the developing sleeve 31 has the same polarity as the N pole, and the developing sleeve 31 is formed of the magnetic member 31b.

As described above in the first embodiment, the developing sleeve 31 is made of a non-magnetic member, and the two magnets 34a and 34
In the case as shown in FIG. 9C in which the space between b and b is a space, the magnetic lines of force are directed perpendicular to the sleeve 31 in the NN repulsive magnetic field, and the magnetic toner is arranged along the lines of magnetic force. It is considered that the sealing performance is improved.

On the other hand, FIG.
In the case where the developing sleeve 31 is a magnetic member 31b and a magnetic member 34c is interposed between the two magnets 34a and 34b as shown in FIG. Since the magnetic toner is more concentrated in the vertical direction and is arranged along the lines of magnetic force, it is considered that the sealing property is further improved.

As described above, by adopting the configuration of the magnet seal member 34 and the developing sleeve 31 described in the present embodiment, two
The action of the repulsive magnetic field of the individual magnets and the action of concentrating the lines of magnetic force by the magnetic members can be used.

Embodiment 3 FIG. 12 is a schematic view in the longitudinal direction of a main part showing a state of a magnet seal member 34 which is an embodiment of the developing device according to the present invention. In the present embodiment, the configuration of the magnet seal member 34 is different from that of the first embodiment, but other configurations are essentially the same as those of the first embodiment.
Since they are the same as those described above, their detailed description is omitted.

In the first embodiment, the magnet seal member 34
Although the two magnets 34a and 34b are arranged so that the N pole and the N pole face each other with the gap A therebetween, in this embodiment, the two magnets 34a and 34b are directly joined without providing a gap. It has become.

More specifically, in this embodiment, FIG.
As shown in FIG. 2, the magnet seal member 34 is a magnet seal member 34 in which magnets 34a and 34b having N and S poles magnetized on their side surfaces are closely joined so that the N and N poles face each other. The developing sleeve 31 is disposed at both ends in the longitudinal direction. In the present embodiment, the magnet seal member 34 is arranged in the longitudinal direction of the developing sleeve 31 so that the S pole, the N pole,
The order of the N pole and the S pole of 4b is as follows.

Also in this embodiment, the state of the lines of magnetic force is shown in FIG.
This will be described with reference to FIG. FIG. 9C illustrates the configuration of the magnet seal member according to the first embodiment, and FIG. 9E illustrates the configuration of the magnet seal member according to the present embodiment. FIG.
In (e), the two magnets 34a and 34b are arranged such that their magnetic poles are parallel to the developing sleeve 31, and
The magnets 34a and 34b are in close contact.

The magnetic force densities in the case of the configuration shown in FIG. 9C are as described in the first and second embodiments.

On the other hand, FIG.
In the case where a configuration in which two magnets 34a and 34b are closely contacted as shown in FIG.
The magnetic toner is more concentrated in the vertical direction, and the magnetic toner is arranged along the lines of magnetic force, so that it is considered that the sealing property is improved.

According to the present embodiment, for example, when a general-purpose and inexpensive ferrite magnet is used, it is usually difficult to exert a large magnetic ability, but as shown in FIG.
By arranging the magnets 34a and 34b close to each other, it is possible to exhibit a large magnetic capability in a narrow range.

As described above, by employing the configuration of the magnet seal member described in this embodiment, even when an inexpensive ferrite magnet is used, the action of the repulsive magnetic fields of the two magnets 34a and 34b can be used. As a result, the magnetic flux density in the vertical direction at the surface position of the developing sleeve could be increased although it was in a narrow range on the surface of the developing sleeve.

Fourth Embodiment FIG. 13 is a schematic longitudinal view of a main part showing a state of a magnet seal member 34 which is an embodiment of the developing device according to the present invention. In the present embodiment, the configuration of the magnet seal member 34 is different from that of the first embodiment, but other configurations are essentially the same as those of the first embodiment.
Since they are the same as those described above, their detailed description is omitted.

In the first embodiment, the magnet sealing member 34 has the two magnets 34a and 34b arranged so that the N pole and the N pole are opposed to each other with the gap A therebetween.
In this configuration, d is disposed with the N pole facing the gap A.

More specifically, in this embodiment, FIG.
As shown in FIG. 3, the magnet seal member 34 is provided with magnets 34a, 34b, 34d from three directions in a U-shape with respect to the gap A such that the N poles face each other. The opening of the magnet faces the developing sleeve 31.

By adopting the structure of the magnet seal member 34 described in the present embodiment, the three magnets 34a and 34
The lines of magnetic force can be concentrated by the action of the repulsive magnetic fields b and 34d.

Embodiment 5 FIG. 14 is a perspective view showing a magnet seal member 34 which is an embodiment of the developing device according to the present invention. In this embodiment, the configuration of the magnet seal member 34 is different from that of the first embodiment.
Other configurations are essentially the same as those in the first embodiment, and a detailed description thereof will be omitted.

In the first embodiment, as shown in FIG. 7, the magnet seal member 34 has the magnets 34a and 34b whose side surfaces are all uniformly magnetized to the N pole or the S pole. As shown in FIG. 13, the magnet seal member 34 has two magnets 34 a and 34 b on which side surfaces of the magnets 34 a and 34 b are alternately magnetized with north poles and south poles. Are always of the same polarity.

With the configuration of the magnet seal member 34 as in this embodiment, the repulsive magnetic fields of the two magnets 34a and 34b can be used, and the lines of magnetic force can be concentrated on the surface of the developing sleeve.

In the first to fifth embodiments, the case where the magnetic developer (magnetic toner) is used as the developer has been described. However, the developer composed of the non-magnetic developer (non-magnetic) toner and the magnetic particles (carrier) is used. A component magnetic developer can also be used, and the same effect can be achieved.

[0069]

As described above, the developing device according to the present invention comprises a developing container containing a magnetic developer or a two-component developer containing magnetic particles and a non-magnetic developer, and a rotatable mounting container. A developer carrier that supports and transports the developer to the image carrier by arranging a magnet inside the developer carrier, wherein at both ends of the developer carrier, a predetermined gap is formed between the outer peripheral surface of the developer carrier and With this configuration, the magnet seal member composed of at least two magnets is arranged so that the opposing surfaces in the longitudinal direction of the developer carrier are magnetic poles of the same polarity. The size of the brush can be increased, and the magnetic brush ears can be formed firmly and precisely. Therefore, the developing device of the present invention, and the process cartridge and the image forming apparatus provided with the developing device, further suppress the leakage of the developer in the longitudinal direction of the developer carrier and the leakage of the developer due to the impact,
Can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a laser beam printer having a process cartridge detachable type equipped with a developing device according to the present invention.

FIG. 2 is a central sectional view of a process cartridge provided with a developing device according to the present invention.

FIG. 3 is a central sectional view of a main part of the developing device according to the present invention.

FIG. 4 is a main sectional view of a main part of the developing device according to the present invention.

FIG. 5 is a perspective view showing one embodiment of a developer carrier and a magnet seal member in the developing device according to the present invention.

FIG. 6 is a longitudinal sectional view of a main part of a developer carrier in the developing device according to the present invention.

FIG. 7 is a perspective view showing one embodiment of a magnetized pattern of a magnet seal member in the developing device according to the present invention.

FIG. 8 is a diagram for explaining a magnetic flux density depending on a magnetic pole arrangement of a magnet.

FIG. 9 is a diagram illustrating a state of lines of magnetic force due to a difference in configuration of a magnet seal member.

FIG. 10 is a perspective view showing another embodiment of the developer carrier and the magnet seal member in the developing device according to the present invention.

FIG. 11 is a longitudinal sectional view of a main part of a developer carrying member in the developing device according to the present invention.

FIG. 12 is a longitudinal sectional view of a main part of a developer carrier showing another embodiment of the magnet seal member in the developing device according to the present invention.

FIG. 13 is a longitudinal sectional view of a main part of a developer carrier showing another embodiment of the magnet seal member in the developing device according to the present invention.

FIG. 14 is a perspective view showing another embodiment of the magnet seal member in the developing device according to the present invention.

FIG. 15 is a front sectional view showing a developing device provided in a conventional process cartridge.

FIG. 16 is a longitudinal sectional view of a main part of a conventional developing device.

FIG. 17 is provided in a conventional process cartridge.
FIG. 10 is a front sectional view showing a developing device using a conventional magnet seal member.

FIG. 18 is a schematic view showing a magnetization pattern of a conventional magnet seal member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image carrier (electrophotographic photosensitive drum) 2 Charging means 3 Developing device 5 Cleaning means 8 Developing means 12 Transport means 10 Process cartridge 30 Developing container 31 Developer carrier (Developing sleeve) 31a Non-magnetic member (Non-magnetic sleeve) 31b Magnetic member 32 Magnet roller 33 Developer layer thickness regulating blade (elastic blade) 34 Magnet seal member 34a, 34b, 34d Magnet 34c Magnetic member

Claims (16)

[Claims] 1. A developing container containing a magnetic developer or a two-component developer containing magnetic particles and a non-magnetic developer as a developer, and a magnet rotatably supported by the developing container and arranged inside. A developer carrying member that carries and transports the developer to the image carrier, wherein the developing device is detachable from the main body of the image forming apparatus, wherein the outer peripheral surface of the developer carrying member is provided at both ends of the developer carrying member. And a magnet seal member comprising at least two magnets with a predetermined gap between the magnet carrier and the magnet carrier having the same polarity in the longitudinal direction of the developer carrier. 2. The developing device according to claim 1, wherein a magnetic member is disposed on at least a portion of the developer carrier that faces a region of the magnet seal member where magnetic poles of the same polarity face each other. 3. The developing device according to claim 1, wherein at least two magnets of the magnet seal member are arranged so that opposing surfaces in the longitudinal direction have magnetic poles of the same polarity via a magnetic member. . 4. The developing device according to claim 1, wherein the at least two magnets of the magnet seal member are arranged so as to be in close contact with each other in a longitudinal direction so that opposing surfaces have magnetic poles of the same polarity. 5. A process cartridge detachably mountable to an image forming apparatus main body, comprising: an image carrier; and a process unit having a developing device having at least a developer carrier acting on the image carrier; At both ends of the developer carrier, with a predetermined gap with the outer peripheral surface of the developer carrier,
A process cartridge, wherein a magnet seal member comprising at least two magnets is arranged in such a manner that opposite surfaces in the longitudinal direction of the developer carrier have magnetic poles of the same polarity. 6. The process cartridge according to claim 5, wherein a magnetic member is disposed on at least a portion of the developer carrier that faces a region of the magnet seal member where magnetic poles of the same polarity face each other. 7. The magnet seal member according to claim 5, wherein at least two magnets of the magnet seal member are arranged so that opposing surfaces in the longitudinal direction have magnetic poles of the same polarity via a magnetic member.
Or the process cartridge of 6. 8. The process cartridge according to claim 5, wherein the at least two magnets of the magnet seal member are arranged so as to be closely in the longitudinal direction and have opposite surfaces with magnetic poles of the same polarity. 9. The process cartridge, wherein the developing device as the process means, a charging means or a cleaning means, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. 9. The process cartridge according to claim 5, wherein the process cartridge is detachable. 10. The process cartridge, wherein at least the developing device as the process means and the image carrier are integrally formed as a cartridge, and the cartridge is detachably mountable to an image forming apparatus main body. The process cartridge according to any one of claims 5 to 8. 11. An image forming apparatus for detachably attaching a process cartridge and forming an image on a recording medium, comprising: (a) an image carrier; and at least a developer carrier acting on the image carrier. Process means having a developing device, wherein at least two ends of the developer carrier are provided at a predetermined gap from the outer peripheral surface of the developer carrier.
Mounting means for detachably mounting a process cartridge to an apparatus main body, wherein a magnet seal member composed of two magnets is arranged so that opposite surfaces in the longitudinal direction of the developer carrier have magnetic poles of the same polarity. And (b) a conveying means for conveying the recording medium. 12. A magnetic member is disposed on at least a portion of the developer carrier that faces a region of the magnet seal member where magnetic poles of the same polarity oppose each other.
1 image forming apparatus. 13. The image according to claim 11, wherein the at least two magnets of the magnet seal member are arranged via a magnetic member such that opposing surfaces in the longitudinal direction have magnetic poles of the same polarity. Forming equipment. 14. The magnet seal member according to claim 11, wherein at least two magnets of the magnet seal member are arranged so as to be closely in the longitudinal direction and have opposite surfaces with magnetic poles of the same polarity.
2 image forming apparatus. 15. The process cartridge, wherein the developing device as the process unit, a charging unit or a cleaning unit, and the image carrier are integrally formed into a cartridge, and the cartridge is attached to the image forming apparatus main body. The image forming apparatus according to any one of claims 11 to 14, wherein the image forming apparatus is detachable. 16. The process cartridge, wherein: the developer carrier as at least the process means;
15. The image forming apparatus according to claim 11, wherein the image carrier and the image carrier are integrally formed as a cartridge, and the cartridge is detachably mountable to a main body of the image forming apparatus.