JP2001201917A - Electrifying device, processing cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable electrifying device, a processing cartridge and an image forming device which can secure satisfactory sealability against vibration, etc., and insulation of an end part insulating member over a long period. SOLUTION: A magnetic carrier binding area 22b where magnetic particles are bound by a magnet 22 and a magnetic carrier binding area 14c by the end part blade magnet 14 disposed so as to overlap each other.

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 having a function of forming an image on a recording material such as a sheet, such as a copying machine, a printer, or a facsimile machine. And a process cartridge for charging the toner.

[0002]

2. Description of the Related Art In recent years, since it has advantages such as low ozone and low power, a contact charging device, that is, a charging member to which a voltage is applied to a member to be charged is brought into contact as a uniform charging member for a photosensitive drum. 2. Description of the Related Art Apparatuses for charging a member to be charged have been put to practical use.

As a charging member of this type, a magnetic brush type device is preferably used from the viewpoint of stability of charging contact.

In a contact charging device of the magnetic brush type, conductive magnetic particles are magnetically constrained directly on a magnet or a sleeve containing a magnet, and are brought into contact with a member to be charged while stopping or rotating. By applying a voltage thereto, charging is started.

When a magnetic brush system is used and a charged body has a surface layer in which conductive fine particles are dispersed on a normal organic photosensitive body, or when an amorphous silicon photosensitive body is used, the bias applied to the contact charging member is reduced. It is possible to obtain a charging potential substantially equal to the DC component on the surface of the member to be charged.

[0006] Such a charging method is called injection charging. The use of the injection charging does not use a discharge phenomenon in which the charging of the member to be charged is performed by using a corona charger, so that a completely ozone-free and low-power-consumption charging is possible, which has attracted attention.

[0007] The charging device charged by the magnetic particles is configured as shown in FIG. FIG. 8 is an explanatory view schematically showing a charging device.

A magnetic carrier contained in a carrier container 24 is supported by a charging sleeve 21 which is a cylindrical and rotatable magnetic carrier carrier made of a non-magnetic material and includes a fixed magnet 22 serving as a magnetic field generating means. The thickness of the carried carrier is regulated by a charging blade 53 to form a thin magnetic particle layer having a predetermined thickness, and the magnetic carrier is conveyed to a charging unit, where the electrophotographic photosensitive member 1 is charged.

At the time of charging, a charging bias in which an AC voltage is superimposed on a DC voltage is applied to the charging sleeve 21 and the electrophotographic photosensitive member 1.
And the outer peripheral surface of the photoreceptor 1 is uniformly charged substantially equal to the DC voltage value by the charge injection charging.

Here, as shown in FIG. 8, the magnetic poles of the magnet 22 have a plurality of magnetic poles in the circumferential direction, such as N1, S1, N2 and S2. As for the action of the magnetic pole, the S2 pole attracts the magnetic carrier in the container and carries it on the charging sleeve 21, and the N1 pole performs the action of transporting the magnetic carrier.

The S1 pole is disposed to face the electrophotographic photosensitive member 1 and has a function of injecting charges onto the electrophotographic photosensitive member 1 to charge the electrophotographic photosensitive member 1. The N2 pole prevents magnetic carrier leakage from the lower part of the container. Act like so.

Generally, the magnet 22 has a cylindrical shape, and each pole is magnetized to the longitudinal end.

An end seal member 55 made of felt, malt plane, or the like is attached to the longitudinal end of the opening formed in the charging container in contact with the charging sleeve 21. Prevents leakage of magnetic particles.

At the longitudinal end of the charging member (in the direction of the generatrix of the photosensitive member), that is, at the end of the magnetized area of the magnet roll included in the sleeve, the magnetic force decreases, and the magnetic brush becomes coarse and contacts the photosensitive member. Becomes unstable, so that it is difficult to uniformly charge even a fine region.

Therefore, a potential difference is generated between the surface of the photosensitive member 1 and the tip of the magnetic brush, and the magnetic particles move from the charging member to the photosensitive member 1.
There is a problem that it adheres to As a result, in long-term durability, the number of carriers as a charging member is reduced, and charging performance is reduced.

Further, the carrier adhering to the photoreceptor 1 is mixed into the developing device to deteriorate the developing performance, or spills into the copier body to cause adverse effects such as contamination.

Therefore, conventionally, a member for electrically insulating the sleeve and the magnetic carrier at the end has been provided, and this has been prevented by cutting off the conductive path between the photosensitive member surface and the conductive member. As an insulating member at the end of the sleeve, an insulating tape such as a Mylar (trade name of polyethylene terephthalate) tape or Teflon tape was used.

FIG. 9 is a potential diagram for explaining the surface potential on the photosensitive member after charging. In FIG. 9, a is a DC bias applied to the charging device. In the case where there is no insulating member, the charged carrier at the end is located at the boundary of the uncharged area as shown in FIG. 9B, and the contact of the magnetic brush with the photoconductor 1 at the end is unstable, Insufficient electrification occurs in a fine area that is not charged, and is subjected to the force of adhering to the photoconductor 1 side.

In addition, the gap between the charged potentials is large inside and outside the boundary of the charged region, and an electric field for attaching magnetic particles is generated toward the outside on the photosensitive member 1.

Therefore, the coating area is extended in the longitudinal direction,
By applying the Mylar tape to the extended portion, the potential drop at the end becomes a slope as shown in FIG. 9C, and the potential at the tip of the magnetic brush also decreases as approaching the boundary of the coating area, and the carrier adhesion electric field decreases.

In the charging device as described above, the opening of the charging container, the charging sleeve 21, the magnet 22, the Teflon felt (end sealing member 55), the magnetic carrier regulating blade (coat area), the end insulating area. Was set as follows. FIG. 10 is an explanatory cross-sectional view of the charging sleeve 21 in the longitudinal direction.

That is, the charge assurance area B for image charging is set according to the transport area A of the recording material to be used. Then, the insulating region is provided at least from the end side with respect to the charging region B,
The width (regulation blade C) of the opening of the charging container is set so that the insulating region is at least 2 mm or more.

As a result, the charging sleeve 21 is coated with the magnetic particles corresponding to the amount of the regulating blade C, so that the inside of the insulating region has the original charging potential, and the insulating region has the potential slope as described above. Formation is possible.

Further, the length D of the magnet 22 is set over the entire area of the regulating blade C, and end seal members 55 are provided outside both ends of the magnet 22 in the longitudinal direction.
This is because the magnetic carrier of the magnet 22 does not draw the magnetic carrier to the end seal member 55.

Further, recently, there is a seal member using a magnetic seal member using a magnetic material such as an iron plate. In this configuration, a magnetic seal member is attached to the opening end of the container at a small distance from the charging sleeve 21, and the magnetic carrier is attracted by the magnetic force of the seal member to prevent leakage of the magnetic carrier.

The magnetic sealing member comprises a charging sleeve 21
End seal member 55 such as felt
, The rotational torque of the charging sleeve 21 becomes smaller,
The motor for rotating the charging sleeve 21 can be reduced in size.

Further, the end seal member 55 such as felt cannot be reused because of durability deterioration due to sliding contact with the charging sleeve 21, whereas the magnetic seal member has no durability deterioration. There is an advantage that it can be reused even when performing.

[0028]

However, in the case of the above-described prior art, the following problems have occurred.

In a contact type end seal member such as felt or maltprene, the end seal member is disposed in contact with a mylar tape or a Teflon tape as the above-mentioned end insulating member, and is subjected to an appropriate pressure to seal the end portion. Had maintained sex.

Therefore, during the rotation operation of the charging sleeve associated with long-term image formation, the insulating member continues to be worn by the contact member, which eventually causes breakage such as cuts, peeling, and abrasion of the tape. Results.

Alternatively, the contact member itself may be peeled off or abraded and the sealing property may not be maintained. In particular, if the magnetic carrier slightly enters between the contact seal member and the insulating member, the deterioration is further accelerated.

When the insulating member is broken, the magnetic carrier adheres to the photoreceptor without maintaining the insulating property at the end, and is mixed into the developing device, and the stable developing performance cannot be maintained. Problems such as spilling and contamination occur.

In addition, there is a possibility that fragments of the tape may enter the charging container or the developing container and impair the basic performance. Even when the contact member is broken, the end sealability is not maintained, and the magnetic carrier spills into the main body, causing a problem such as contamination. Also, fragments of the contact member may enter the charging container or the developing container and impair basic performance.

In addition, in the injection charger, the area where the magnetic particles are in contact with the member to be charged must be widened in order to secure stable charging properties over a long period of time.
It is necessary to greatly increase the superposition of the magnetic particles on the sleeve per unit area with respect to the gap between the charging sleeve and the member to be charged.

Therefore, the magnetic particles at the end of the sleeve are crushed by the charging sleeve and the member to be charged when passing through the gap between the charging sleeve and the member to be charged, and are likely to spread outside the uncoated magnetic particles. If the magnetic particles enter a region where there is no regulation, the magnetic particles cannot be held on the magnetic particle carrier and cause leakage of the magnetic particles regardless of the magnetic particle adhesion electric field.

Particularly, in a portable copying machine, a portable printer or the like in which a user moves the apparatus,
Intense vibration may be applied while the device is moving.

In a process cartridge in which the electrophotographic photosensitive member and the charging device are formed into a cartridge,
When the cartridge is attached to or detached from the image forming apparatus main body, an impact such as a vertical swing may be applied to the cartridge.

With respect to such severe vibrations and shocks,
In order to ensure the sealing performance of the magnetic sealing member, a conventional magnetic plate alone is not sufficient, and it is necessary to enhance the magnetic force or sealing performance of the sealing member.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a sufficient sealing property against vibration and the like and a long-term insulating property of the end insulating member. It is an object of the present invention to provide a highly reliable charging device, a process cartridge, and an image forming apparatus capable of ensuring image quality.

[0040]

According to the present invention, there is provided a charging agent container having an opening for storing a charging agent containing a charging agent having conductive magnetic particles. A charging agent carrier provided at an opening of the charging agent container and supporting a charging agent, and a magnetic field generating means included in the charging agent carrier and generating a magnetic field to restrain the charging agent by a magnetic force, Near the end of the magnetic field generating means, provided in a non-contact with the charging agent carrier, to seal the charging agent in the charging agent container, comprising an end sealing member having a magnetic material, In a charging device that charges the charged object by applying a charging bias by bringing the charged agent held on the charged agent carrier into contact with the charged object,
It is characterized in that the first magnetic force effective region where the magnetic particles can be restrained by the magnetic field generating means and the second magnetic force effective region made of the magnetic material of the end seal member overlap each other.

The end of the first magnetic force effective area is provided between the end of the end seal member on the side of the magnetic field generating means and the end on the side opposite to the magnetic field generating means. It is also suitable.

It is also preferable that the end of the magnetic field generating means is provided between the end of the end sealing member on the side of the magnetic field generating means and the end of the end sealing member on the side opposite to the magnetic field generating means. It is.

Preferably, the magnetic material of the end seal member is a magnet.

A charging agent regulating member for regulating the charging agent carried by the charging agent carrier at the opening to a predetermined thickness, and an insulating member for insulating the charging agent on the end surface of the charging agent carrier. It is preferable that an end portion of the charging agent regulating member is provided so as to be located in a region insulated by the insulating member.

A process cartridge is characterized by comprising the charging device described above and an image carrier on which an electrostatic latent image is formed after being charged by the charging device as a member to be charged.

It is also preferable that the image carrier has a charge injection layer on the surface.

In the image forming apparatus, the charging device described above, or the process cartridge described above, and a recording material that is transported after developing an electrostatic latent image formed on a charged image carrier is developed. And an image forming means for transferring the image to the image forming apparatus.

[0048]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, the shape, and the relative arrangement thereof should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions, and are not intended to limit the scope of the invention to the following embodiments. Note that the same components as those described in the section of the related art are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 6 is a schematic configuration diagram of an example of an electrophotographic apparatus as an image forming apparatus. The electrophotographic apparatus according to the present embodiment is a laser beam printer using an electrophotographic process. First, an image forming operation by the image forming unit will be described.

Reference numeral 1 denotes a rotating drum type electrophotographic photosensitive member as an image carrier. In the present embodiment, O of 30 mm in diameter is used.
PC photoreceptor (organic photoreceptor), 1 clockwise as indicated by the arrow
It is driven to rotate at a process speed (peripheral speed) of 00 mm / s.

Reference numeral 2 denotes a magnetic brush charger serving as a contact charging member in contact with the photoreceptor 1, and a magnetic force of a magnet (magnetic field generating means) 22 is attached to a rotatable non-magnetic charging sleeve (charging agent carrier) 21. Conductive magnetic powder (magnetic particles)
23 are attached.

The magnetic brush charger 2 is applied with a bias in which a rectangular alternating voltage of 1000 Hz and 800 V is superimposed on a charging bias of a DC voltage of -700 V from a charging bias applying power source S1. The outer peripheral surface of the body 1 is uniformly charged to approximately -700V.

The charged surface of the photoreceptor 1 is intensity-modulated in accordance with a time-series electric digital pixel signal of target image information output from a laser beam scanner (not shown) including a laser diode, a polygon mirror, and the like. The scanning exposure L by the laser beam is performed, and an electrostatic latent image corresponding to the target image information is formed on the peripheral surface of the photoconductor 1. The electrostatic latent image is developed as a toner image by a reversal developing device 3 using a magnetic one-component insulating toner.

Reference numeral 3a denotes a diameter 1 containing the magnet 3b.
6 mm is a non-magnetic phenomenon sleeve. The phenomenon sleeve is coated with the above-mentioned negative toner, and is rotated at the same speed as the photosensitive member 1 with the distance from the surface of the photosensitive member 1 fixed at 300 μm, and developed on the sleeve 3 a. A developing bias voltage is applied from a bias power source S2.

As the voltage, a DC voltage of -500 V and a rectangular AC voltage having a frequency of 1800 Hz and a peak-to-peak voltage of 1600 V are superimposed, and a jumping phenomenon is caused between the sleeve 3a and the photosensitive member 1.

On the other hand, a transfer material P as a recording material is supplied from a paper supply unit (not shown), and a transfer of medium resistance as a contact transfer means contacting the photosensitive member 1 with a predetermined pressing force. It is introduced at a predetermined timing into a pressure nip (transfer portion) T with the roller 4. A predetermined transfer bias voltage is applied to the transfer roller 4 from a transfer bias application power source S3.

In this embodiment, the roller resistance value is 5 × 10
^The transfer was performed by applying a DC voltage of +2000 V using an 8Ω resistor.

The transfer material P introduced into the transfer section T is conveyed by sandwiching the transfer section T, and the toner image formed and carried on the surface of the photoreceptor 1 on its surface side is sequentially subjected to electrostatic force and pressing force. Is transcribed.

The transfer material P to which the toner image has been transferred is separated from the surface of the photoreceptor 1 and introduced into a fixing device 5 such as a heat fixing system, where the toner image is fixed and the image formed matter (print, copy) ) Is discharged out of the apparatus.

After the transfer of the toner image to the transfer material P, the surface of the photoreceptor is cleaned by the cleaning device 6 to remove adhered contaminants such as residual toner, and is repeatedly used for image formation.

In the electrophotographic apparatus of the present embodiment, the four process devices of the photosensitive member 1, the magnetic brush charger 2, the developing device 3 and the cleaning device 6
The cartridge type device is a cartridge type device which can be detached and exchanged at a time with respect to the image forming apparatus main body by embracing it in the cartridge body, but is not limited thereto.

As the photosensitive drum 1 used in the present invention, a commonly used organic photosensitive member or the like can be used. Preferably, the resistance of the photosensitive drum is 10 ⁹ on the organic photosensitive member.
And those with a surface layer having a material of ~10 ^{1 4} Ω · cm,
When an amorphous silicon photoreceptor is used, charge injection charging can be realized, which is effective in preventing ozone generation and reducing power consumption.

Further, the chargeability can be improved. Therefore, in the present embodiment, a photosensitive drum which is a negatively charged organic photosensitive member and has the following first to fifth five layers provided in order from the bottom on an aluminum drum base having a diameter of 30 mm is used.

The first layer is a subbing layer, and is a conductive layer having a thickness of 20 μm provided to smooth defects or the like of an aluminum substrate (hereinafter, referred to as an aluminum substrate).

The second layer is a positive charge injection preventing layer, which serves to prevent positive charges injected from the aluminum substrate from canceling out negative charges charged on the surface of the photoreceptor, and comprises an amylan resin and methoxymethylated nylon. 1 × 10 ⁶ Ω
This is a medium-resistance layer having a thickness of 1 μm and a resistance adjusted to about cm.

The third layer is a charge generating layer, which is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and generates a positive and negative charge pair upon exposure.

The fourth layer is a charge transport layer in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore, the negative charges charged on the photoreceptor surface cannot move through this layer, and only the positive charges generated in the charge generation layer can be transported to the photoreceptor surface.

The fifth layer is a charge injection layer, which is a coating layer of a material in which ultrafine SnO ₂ particles are dispersed in a binder of an insulating resin. Specifically, a coating is made of a material in which SnO ₂ particles having a particle diameter of about 0.03 μm, obtained by doping an insulating resin with a light-transmitting insulating filler to reduce the resistance (conducting conductivity), are dispersed in the resin by 70% by weight. It is an engineering layer.

The coating solution thus prepared was applied to a thickness of about 4 μm by a dipping coating method to form a charge injection layer.
At this time, a 5 mm uncoated area of the photosensitive layer was present at the far end of the photosensitive member.

Next, the magnetic brush charger 2 used in the present embodiment will be described in detail. The magnetic brush charger 2 includes a non-magnetic charging sleeve 21 in which magnetic particles 23 are formed in a brush shape by a magnetic field on a rotatable non-magnetic charging sleeve 21 having a fixed magnet 22 provided inside and having a rotatable outer diameter of 16 mm. The magnetic particles 23 are transported with the rotation of 21.

The non-magnetic charging sleeve 21 rotates in the counter direction with respect to the photosensitive drum 1, and in the present embodiment, the rotation speed of the photosensitive drum 1 is 100 mm /.
s, the magnetic brush charger 2 is rotating at 150 mm / s.

When a charging voltage is applied to the non-magnetic charging sleeve 21, a charge is given from the magnetic particles 23 to the photosensitive drum 1 and charged to a potential corresponding to the charging voltage. The higher the rotation speed, the better the charging uniformity tends to be.

The magnetic carrier used as the charging member has an average particle diameter of 10 to 100 μm and a saturation magnetization of 2 μm.
00 to 2500 C / cm ³ (20 to 250 emu / c
m ³ ) and a resistance of 1 × 10 ² to 1 × 10 ¹⁰ Ω · cm, preferably 1 × 10 ⁶ Ω · cm or more in consideration of the presence of insulation defects such as pinholes in the photosensitive drum. It is preferable to use one.

In order to improve the charging performance, it is better to use one having as small a resistance as possible. In this embodiment, the average particle diameter is 25 μm, the saturation magnetization is 2000 C / cm.
³ (200 emu / cm ³ ), resistance is 5 × 10 ⁶ Ω · cm
Was used.

Here, the resistance value of the carrier has a bottom area of 2
After putting 2 g of the carrier into a 28 (mm ² ) metal cell,
The measurement was performed by applying a load of 6.6 kg / cm ² and applying a voltage of 100 V.

As the magnetic particles, a resin carrier formed by dispersing magnetite as a magnetic material in a resin and dispersing carbon black for conductivity and resistance adjustment;
Alternatively, a material in which the surface of a single magnetite such as ferrite is oxidized and reduced to adjust the resistance, or a material in which the surface of a single magnetite such as ferrite is coated with a resin and the resistance is adjusted is used.

The nip width formed with respect to the photosensitive drum 1 was adjusted to be approximately 6 mm.

In the present embodiment, DC voltage −70
A rectangular alternating voltage of 1000 Hz and 800 V with respect to 0 V
By applying a bias superimposed on the charging device to the charger, good charging properties could be obtained.

Next, the end processing of the charging device used in the present embodiment will be described. FIG. 7 is a schematic configuration diagram illustrating the arrangement of the charging sleeve 21 and the photoconductor 1 in the longitudinal direction in the present embodiment.

The charge assurance area B is determined by the distribution length from the center.
Is set to 159.4 mm, and the end side from that is set as an insulating region. On the other hand, the length of the magnetic particle regulating member (charging agent regulating member), that is, the magnetic particle coating region C is set to 1
In the case of 65 mm, the insulating region and the magnetic particle coated region overlap with 5.4 mm.

Accordingly, no current flows from the insulating region on the charging sleeve 21. Therefore, the charging potential at the contact portion between the magnetic particles 23 having a length of 159.4 mm or less and the photosensitive member 1 is 159.
It gradually decreases from the position of 4 mm, and becomes 0 at the position of 165 mm.
A slope of V is formed, and the potential difference between the tip of the magnetic brush and the surface of the photoreceptor, that is, the magnetic particle adhesion electric field does not greatly occur.

Also, the inner wall of the injectable collection container is 166 mm,
The thickness is 1 mm, and a sealing member for preventing leakage of the magnetic carrier exists outside the charging sleeve 21.
The length of the magnet 22 included in the charging sleeve 21 is 167 mm, and the end of the charging sleeve 21 is 180 mm.

Here, the seal configuration will be described.

As shown in the longitudinal sectional view of FIG. 1A, plate-like magnets (hereinafter referred to as end seal members) are provided at both ends in the longitudinal direction of the opening 10e (only one side is shown in FIG. 1). , End plate magnets) 14 are attached.

As shown in the cross-sectional view in the lateral direction of FIG. 1B, the end plate magnets 14 have a very small interval (in the present embodiment, so as not to contact the surface of the charging sleeve 21). Is attached to the edge of the opening 10e with a distance of 0.4 mm.
e in the longitudinal direction).

A charged area of the charging sleeve 21 is formed between the end plate magnets 14 attached to both sides, and even if the magnetic carrier in the charged area leaks from the longitudinal end of the opening 10e to the outside, the magnetic seal is formed. The magnetic carrier is attracted by the end plate magnet 14 as a member, and leakage of the magnetic carrier to the outside is prevented.

In the present embodiment, in order to more reliably prevent the leakage of the magnetic carrier, the magnet 2
The two magnetized end portions 22a are formed such that, in the longitudinal direction of the opening 10e, the widthwise inner end (the charging area side by the charging sleeve 21) 14a of the end plate magnet 14 and the widthwise outer end (the non-charging side by the charging sleeve 21). The positions of the magnet 22 and the end plate magnet 14 are set so as to be located between the magnet 22 and the end plate magnet 14.

With the above configuration, FIG.
As shown in (c), the magnetized end 22a of the magnet 22
In the vicinity, a magnetic carrier constrained area 22b (first magnetic force effective area) due to the magnetic force of the magnet 22 and a magnetic carrier constrained area 14c (second magnetic force) due to the magnetic force of the end plate magnet 14.
And the magnetic carrier is reliably restrained by the overlapping restraining force of the two.

That is, by overlapping the magnet 22 with the end plate magnet 14, the magnetic carrier binding force of the end plate magnet 14 is supplemented by the magnetic carrier binding force of the magnet 22, and the magnetized end 22 a of the magnet 22. By increasing the magnetic carrier restraining force in the vicinity, a sufficient sealing property can be obtained.

Therefore, even if an impact or the like is given to the process cartridge 20 when the process cartridge 20 is attached to or detached from the electrophotographic image forming apparatus, the end plate magnet 1
The leakage of the magnetic carrier from the minute gap between the charging carrier 21 and the surface of the charging sleeve 21 is reliably prevented.

In contrast to the above configuration, for example, FIG.
As shown in (b), the magnetized end 22a of the magnet 22
Is set outside the outer end 14b of the end plate magnet 14, as shown in FIG.
Within the width of the end plate magnet 14, the magnetic carrier constrained area 14c of the magnetic seal member 14 and the magnetic carrier constrained area 22b of the magnet 22 overlap, so that sufficient sealing properties can be obtained in this part.

However, the outer end 14b of the end plate magnet 14
Since the magnetic force of the magnet 22 is generated outside the magnetic carrier, the magnetic carrier may be drawn out by the magnetic force.

At this time, as shown in FIG. 3, when the process cartridge 20 receives an impact in the direction of the arrow X, the magnetic carrier t restrained by the magnetic force of the magnetized end 22a of the magnet 22 escapes from the restraint. May leak to the outside.

As shown in FIGS. 4A and 4B, the magnetized end 22a of the magnet 22 is
4 is set inside the inner end portion 14a of the end plate magnet 14 as shown in FIG.
A gap is generated between the magnetic carrier constrained region 14c of the magnet 22 and the magnetic carrier constrained region 22b of the magnet 22.

For this reason, the end plate magnet 14 is sealed only by the magnetic carrier restraining force of the end plate magnet 14 as in the conventional case.

Therefore, as shown in FIG. 5, it is necessary to increase the magnetic force of the end plate magnet 14 in order to prevent the magnetic carrier from leaking even when an impact in the direction of arrow X is applied to the process cartridge 20. .

Therefore, by using a magnet as in the present invention and configuring the present embodiment, a sufficient sealing property against vibrations and the like and a long-term insulating property of the end insulating member are ensured. This makes it possible to reliably prevent leakage of the magnetic carrier.

In this embodiment, the charging device is the photosensitive member 1
Although the example in which the cartridge is provided in the process cartridge 20 is shown, the charging device having the above-described seal configuration may be directly incorporated in the main body of the electrophotographic image forming apparatus. For example, in the case of a handy carry type image forming apparatus, In addition, it is possible to reliably prevent leakage of the magnetic carrier even when vibration is applied during operation.

[0099]

As described above, according to the present invention,
Since the first effective magnetic force region in which the magnetic particles can be restrained by the magnetic field generating means and the second effective magnetic force region of the magnetic material of the end sealing member are provided so as to overlap with each other, the magnetized end of the magnetic field generating means is provided. Since the magnetic particles are constrained by the magnetic force of the magnetic field generating means and the magnetic force of the end sealing member, the leakage of the magnetic carrier can be reliably prevented even when the vibration or the like is severe without increasing the magnetic force of the end sealing member. And a highly reliable device can be provided.

The end seal member is provided in non-contact with the charging agent carrier, and the end portion of the charging agent regulating member is provided so as to be located in a region insulated by the insulating member. Insulation can be maintained for a long period of time without damaging the Mylar tape or the like mounted as a member, the magnetic particle adhesion electric field can be kept small, and adverse effects due to magnetic particles can be prevented.

[Brief description of the drawings]

FIGS. 1A and 1B are schematic sectional views showing a relationship between a magnet as a magnetic field generating means and an end plate magnet as an end seal member, and FIG. It is a figure explaining the relation of the magnetic force of a magnet.

FIG. 2 is a diagram illustrating a case where a magnetized end of a magnet is located outside an outer end of an end plate magnet.

FIG. 3 is a diagram illustrating a possibility of carrier leakage when the magnetized end of the magnet is located outside the outer end of the end plate magnet.

FIG. 4 is a diagram illustrating a case where the magnetized end of the magnet is located inside the inner end of the end plate magnet.

FIG. 5 is a diagram illustrating the possibility of carrier leakage when the magnetized end of the magnet is located inside the inner end of the end plate magnet.

FIG. 6 is a schematic configuration diagram of an image forming apparatus.

FIG. 7 is a schematic diagram illustrating a configuration of a charging device in a longitudinal direction.

FIG. 8 is a schematic diagram illustrating the configuration of a magnetic brush injection charging device.

FIG. 9 is a diagram illustrating the relationship between charging potentials in injection charging.

FIG. 10 is an explanatory diagram of a schematic configuration in a longitudinal direction of a conventional charging device.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Magnetic brush charger 3 Developing device 4 Transfer roller 5 Fixing device 6 Cleaning device 10e Opening 14 End plate magnets 14a, 14b End 20 Process cartridge 21 Charging sleeve 22 Magnet 22a Magnetizing end Part 22b Magnetic carrier restricted area 23 Conductive magnetic powder 24 Carrier container 53 Charging blade 55 End seal member

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Komiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koichi Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Kenichi Shibuya 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H003 AA12 BB11 CC04 DD03 EE11 2H071 BA04 DA06 DA08 DA13 DA15

Claims (8)

[Claims] 1. A charging agent container having a charging agent storage portion for storing a charging agent having conductive magnetic particles, the charging agent container having an opening, and the charging agent container being provided in the opening of the charging agent container and carrying a charging agent. A charging agent carrier; a magnetic field generating unit that is included in the charging agent carrier and generates a magnetic field so as to constrain the charging agent by a magnetic force; and near an end of the magnetic field generating unit, with respect to the charging agent carrier. An end seal member having a magnetic material, which is provided in a non-contact manner and seals the charging agent in the charging agent container, wherein the charging agent carried by the charging agent carrier is brought into contact with the member to be charged. A charging device that charges the member to be charged by applying a charging bias to the first magnetically effective region in which the magnetic particles can be restrained by the magnetic field generating means and a magnetic material of the end sealing member. The effective magnetic field of 2 A charging device, characterized by being provided so that. 2. An end of the first magnetic force effective region is located between an end of the end seal member on the side of the magnetic field generating means and an end of the end seal member on the side opposite to the magnetic field generating means. The charging device according to claim 1, wherein the charging device is provided. 3. An end of the magnetic field generating means is provided so as to be located between an end of the end seal member on the side of the magnetic field generating means and an end of the end sealing member on the side opposite to the magnetic field generating means. The charging device according to claim 1, wherein: 4. The charging device according to claim 1, wherein the magnetic material of the end seal member is a magnet. 5. A charging agent regulating member that regulates a charging agent carried on the charging agent carrier to a predetermined thickness at the opening, and an insulating member that insulates the charging agent from an end surface of the charging agent carrier. 5. The charging device according to claim 1, wherein the charging agent regulating member is provided such that an end of the charging agent regulating member is located in a region insulated by the insulating member. 6. apparatus. 6. At least one of claims 1 to 5
13. A process cartridge comprising: the charging device according to claim 13; and an image carrier on which an electrostatic latent image is formed after being charged by the charging device. 7. The process cartridge according to claim 6, wherein the image carrier has a charge injection layer on a surface. 8. A charging device according to claim 1, or a process cartridge according to claim 6, and an electrostatic latent image formed on a charged image carrier. And an image forming means for developing the image and transferring it to a recording material conveyed.