JPH0973257A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a magnetic field from being generated between a magnetic pole confining a magnetic member and a cleaner and, therefore, to prevent the decrease in a contact area contributing to charging. SOLUTION: A magnetic brush charger 2 which is applied a voltage is composed of a conductive sleeve 2a, a magnet roll 2b incorporated in the conductive sleeve 2a, and magnetic conductive particles 2c, and it charges a photoreceptor 1 with the magnetic conductive particles 2c. After the transfer of a toner image formed on the photoreceptor 1, residual matters sticking to the surface of the photoreceptor 1 are removed by the cleaning member 6a supported by the nonmagnetic support member 6b. This prevents a magnetic field from being generated between the magnetic pole confining the magnetic conductive particles 2c and the cleaning member 6a.

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 in which a magnetic member is brought into contact with a member to be charged for charging and discharging.

[0002]

2. Description of the Related Art Image formation in an electrophotographic or electrostatic recording type image forming apparatus is performed as follows.
First, the surface of an object to be charged such as an electrophotographic photoreceptor or an electrostatic recording dielectric is uniformly charged by a charger. Then, for example, in the case of the electrophotographic method, light corresponding to the original image is next irradiated by the exposure section to remove the charged electric charge of the charged body part irradiated with the light. As a result, an electrostatic latent image corresponding to the original image is formed. Then, in the developing unit, the electrostatic latent image is developed to form a visible image. This visible image is transferred to a transfer material at the transfer section and further fixed by a fixing device. Further, the transfer residual toner (developer) which has not been transferred at the transfer portion is removed from the surface of the charged body by the cleaning member.

Conventionally, in an electrophotographic type or electrostatic recording type image forming apparatus, a corona charger has been used as a charging processing means for a charged body such as an electrophotographic photosensitive member or an electrostatic recording dielectric. 2. Description of the Related Art In recent years, a contact charging device has been put into practical use, which is a system in which a charger to which a voltage is applied is brought into contact with an object to be charged to perform charging. This is for the purpose of lowering ozone or lowering power consumption.In particular, in a roller charging type contact charging device, a conductive elastic roller is brought into pressure contact with a member to be charged and a voltage is applied to the member. The charged body is charged.

However, even in the roller charging type contact charging device, since charging is performed by discharging from the conductive elastic roller to the member to be charged, a voltage higher than a certain threshold value (charging start voltage Vth) is applied. Charging is started for the first time.
For example, in the case where an elastic roller is brought into pressure contact with an OPC photosensitive member having a thickness of 25 μm as a member to be charged for charging processing, a voltage of about 640 V or more is applied to the elastic roller, The surface potential of the photoconductor starts increasing, and thereafter, the surface potential of the photoconductor linearly increases with a slope of 1 with respect to the applied voltage.

That is, in order to obtain the surface potential Vd of the photoreceptor required for electrophotography, it is necessary to apply a DC voltage equal to or higher than (Vd + Vth), which is the surface potential plus the charging start voltage, to the elastic roller. As described above, in the DC charging method in which only the DC voltage is applied to the elastic roller to charge the charged body, the resistance value of the elastic roller fluctuates due to environmental changes or the photosensitive body as the charged body is scraped. Since the film thickness changes, the charging start voltage Vth fluctuates, and it is difficult to set the charging potential of the photoconductor to a desired value.

Therefore, in order to further uniformize the charging, as disclosed in Japanese Patent Laid-Open No. 63-149669, a DC voltage corresponding to a desired surface potential Vd has a peak of 2 × Vth or more. An AC charging method is used in which an oscillating voltage in which an AC component having a voltage between them is superimposed is applied to an elastic roller. This is for the purpose of leveling the potential by the AC component, and the surface potential Vd of the photoconductor converges to a value at the center between the peaks of the AC voltage and is not affected by external disturbances such as the environment. Absent.

However, even in such a contact charging device, since the essential charging mechanism uses the discharge phenomenon from the elastic roller to the photosensitive member, as described above, the charging voltage is the surface of the photosensitive member. A value higher than the electric potential is required, and a small amount of ozone is generated.

Therefore, as a new charging method, a direct injection charging method by directly injecting charges into the photoconductor is disclosed in Japanese Patent Laid-Open No.
It is proposed in Japanese Patent No. 3921. In this direct injection charging method, a voltage is applied to a contact conductive member such as a charging roller, a charging brush or a charging magnetic brush, and charges are contact-injected into a charge holding member such as a trap level or conductive particles on the surface of the photoconductor. The magnetic member is a magnetically constrained magnetic particle or magnetic material. Sulfur? It is formed by. In this direct injection charging method, since the discharge phenomenon is not used, the voltage required for charging is only the surface potential of the desired photoconductor and no ozone is generated.

On the other hand, residual adhering substances such as residual toner adhere to the surface of the photoconductor even after the toner image is transferred onto a transfer paper as a recording material. The cleaning device is
It removes residual deposits on the surface of the photoreceptor, and includes a cleaning member such as an elastic blade made of urethane or silicon, a magnetic brush or a fur brush, a supporting member for supporting the cleaning member, and the cleaning member and the supporting member. It is composed of a cleaning container to be housed.

[0010]

However, in any of the conventional image forming apparatuses, the downsizing is advanced, the diameter of the photoconductor is reduced, the charging device and the cleaning device are arranged close to each other, and the cleaning member is used. Is in contact with the photoconductor, so magnetic particles or magnetism? Sulfur? A magnetic field is formed between the magnetic support member that supports the cleaning member closest to the magnetic member and the magnetic pole such as the magnet roller that holds the magnetic member, or the magnetic member is mixed in the cleaning device. When it is present, a magnetic field is formed. As a result, the magnetic particles or magnetic sulphate, which is a magnetic member, are constrained in the magnetic field, the contact area between the magnetic member that contributes to charging and the member to be charged is reduced, and the charging uniformity is gradually lost and the charging ability is reduced. The problem arises that

Therefore, the present invention has been made in order to solve the above-mentioned problems, and prevents the magnetic member from being formed between the magnetic poles that restrain the magnetic member and the cleaning device. It is an object of the present invention to provide an image forming apparatus in which a contact area between a charged body and a charged body is not reduced.

[0012]

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention includes a magnetic brush charger that applies a voltage to a magnetic member to charge a member to be charged, and After transferring the toner image formed on the charged body,
A cleaning device for removing residual adhered substances adhering to the surface of the body to be charged, wherein at least a part of the cleaning device is formed of a non-magnetic material.

The cleaning device in the image forming apparatus according to the second invention comprises a cleaning member and a supporting member for supporting the cleaning member, and the supporting member is formed of a non-magnetic material.

In the cleaning device of the image forming apparatus according to the third aspect of the present invention, in the cleaning device, a supporting member that supports the cleaning member is attached to a cleaning container, and the cleaning container is formed of a non-magnetic material.

In the image forming apparatus according to the fourth invention, the cleaning member is a cleaning blade.

The cleaning member in the image forming apparatus according to the fifth aspect of the invention comprises a fur brush and a removing member for removing the residual adhered matter adhering to the fur brush.

In the image forming apparatus according to the sixth invention, the removing member is made of a non-magnetic material.

In the image forming apparatus according to the seventh aspect of the invention, the fur brush and the removing member are incorporated in a non-magnetic conduit through which residual deposits pass.

[Operation] According to the first aspect of the present invention, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the cleaning device, and thus the magnetic member and the non-charged body contributing to charging. The contact area with will not be reduced.

According to the second aspect of the present invention, no magnetic field is formed between the magnetic pole for restraining the magnetic member and the supporting member, so that the contact area between the magnetic member contributing to charging and the member to be charged is reduced. And good charging uniformity is ensured.

According to the third aspect of the present invention, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the cleaning container, and the contact area between the magnetic member contributing to charging and the member to be charged is reduced. Is eliminated, and good charging uniformity is secured.

According to the fourth invention, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the cleaning blade, and the contact area between the magnetic member contributing to charging and the member to be charged is reduced. Is eliminated, and good charging uniformity is secured.

According to the fifth aspect of the invention, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the fur brush, and the contact area between the magnetic member contributing to charging and the member to be charged is reduced. Is eliminated, and good charging uniformity is secured.

According to the sixth aspect, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the conduit, and the contact area between the magnetic member contributing to charging and the member to be charged may be reduced. And good charging uniformity is ensured.

According to the seventh aspect of the present invention, a magnetic field is not formed between the magnetic pole for restraining the magnetic member and the removing member for removing the residual adhering member, and the contact region between the magnetic member contributing to charging and the member to be charged. Does not decrease, and good charging uniformity is secured.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus, and FIG. 2A is an enlarged sectional view showing a magnetic brush charger in contact with a photoconductor. (B) is a conceptual diagram equivalently showing (a). The image forming apparatus of this embodiment is a laser beam printer using an electrophotographic process. In FIG. 1, a rotary drum type electrophotographic photosensitive member (hereinafter referred to as “photosensitive member”) as a member to be charged 1
Will be described later in detail, but is 100 mm / sec in the direction of arrow R1.
Is driven to rotate at the process speed (peripheral speed). A magnetic brush charger 2 is arranged in contact with the photoconductor 1. The magnetic brush charger 2 is a non-magnetic rotatable conductive sleeve 2a, a magnet roll 2b contained in the conductive sleeve 2a, and a magnetic member magnetically constrained on the conductive sleeve 2a by the magnet roll 2b. Magnetic conductive particles 2c. The conductive sleeve 2a is rotatably supported by the magnet roll 2b in a fixed state, and rotates in the same direction as the arrow R1 direction of the photoconductor 1 at a peripheral speed of 100% with respect to the peripheral speed of the photoconductor 1. The magnetic brush charger 2 has a charging bias power source S.
A DC charging bias of 1 to -700V is applied, and the outer peripheral surface of the photoconductor 1 is uniformly charged to approximately -680V. The surface to be charged of the photoconductor 1 is scanned and exposed by a laser beam. This scanning exposure is intensity-modulated with respect to a time-series electric digital pixel signal of image information output from a laser beam scanner (not shown) such as a laser diode and a polygon mirror. An electrostatic latent image corresponding to the target image information is formed on the surface. The reversal developing device 3 using the magnetic one-component insulating toner develops the electrostatic latent image formed on the photoconductor 1 into a toner image, and rotates the non-magnetic developing sleeve 3a having a diameter of 16 mm with respect to the magnet roll 3b. It is possible. Then, with the distance between the surface of the non-magnetic developing sleeve 3a and the surface of the photoconductor 1 fixed at 300 μm,
The magnet roll 3b is rotated at the same speed as the photoconductor 1 to perform development. The non-magnetic developing sleeve 3a has a DC voltage of -500V from the developing bias power source S2 and a frequency of 1800V.
A developing bias voltage in which a rectangular alternating current voltage having a frequency of Hz and a peak-to-peak voltage of 1600 V is superimposed is applied. As a result, the non-magnetic developing sleeve 3a is coated with the magnetic one-component insulating toner, and jumping development is performed between the non-magnetic developing sleeve 3a and the photoconductor 1.

On the other hand, a medium resistance transfer roller 4 as contact transfer means is in contact with the photosensitive member 1 with a predetermined pressing force. Then, the transfer sheet P as a recording material supplied from a sheet feeding section (not shown) is nipped and conveyed to a pressure contact nip section (transfer section) T between the transfer roller 4 and the photoconductor 1 at a predetermined timing. Will be introduced. A predetermined transfer bias voltage is applied to the transfer roller 4 from the transfer bias power source S3. In this embodiment, the resistance value of the transfer roller 4 is 5 × 10 ⁸
Ω is used and the voltage of the transfer bias power source S3 is +
A DC voltage of 2000V is applied. The transfer paper P is nipped and conveyed, and is introduced into a pressure contact nip portion (transfer portion) T at a predetermined timing. At the transfer portion T, the toner image carried on the surface of the photoconductor 1 is electrostatically pressed and pressed. And sequentially transfer. The transfer paper P that has received the transfer of the toner image is separated from the surface of the photoconductor 1 and is introduced into a fixing device 5 such as a thermal fixing system to fix the toner image, and is transferred outside the device as an image formed product (print, copy). Is discharged to.
Further, residual adhered substances such as residual toner adhere to the surface of the photoconductor 1 after the toner image is transferred onto the transfer paper P. The cleaning device 6 removes residual deposits on the surface of the photoconductor 1, and the surface of the photoconductor 1 is cleaned by the cleaning device 6 so that the photoconductor 1 is repeatedly used for image formation. The cleaning device 6 is a urethane rubber cleaning blade (cleaning member).
6a is supported by a non-magnetic support member 6b made of stainless steel or the like, and the support member 6b is attached to a non-magnetic cleaning container 6c. In addition,
In the image forming apparatus according to the present embodiment, four process devices including a photoconductor 1, a magnetic brush charger 2, a reversal developing device 3 and a cleaning device 6 are built in a cartridge C, and the cartridge C is attached to the main body of the image forming device. Although the example in which the photosensitive member 1, the magnetic brush charger 2, the reversal developing device 3, and the cleaning device 6 are supported by the cartridge is not limited to the structure incorporated in the cartridge. .

Next, the photoconductor 1 in the present embodiment will be described.

The photosensitive member 1 is a negatively charged OPC photosensitive member, and is 5 on an aluminum drum substrate having a diameter of 30 mm.
Two functional layers are provided in order from the bottom.

The first layer is an undercoat layer which is a conductive layer having a thickness of about 20 μm, and is for leveling defects such as a drum base made of aluminum and for preventing moire due to reflection of laser exposure. It is provided.

The second layer is a positive charge injection preventing layer, which is a medium resistance layer having a thickness of about 1 μm, and cancels the negative charge charged on the surface of the photosensitive member by the positive charge injected from the aluminum drum base. The resistance is adjusted to about 10 ⁶ Ωcm by the amylan resin and methoxymethylated nylon.

The third layer is a charge generation layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin, and positive and negative charge pairs are generated by laser exposure.

The fourth layer is a charge transport layer that does not move the negative charges charged on the surface of the photoconductor 1 but transports only the positive charges generated in the charge generation layer to the surface of the photoconductor 1, and is a polycarbonate resin. It is a P-type semiconductor in which hydrazone is dispersed.

Therefore, the negative charges charged on the surface of the photoconductor 1 cannot move in the charge transport layer, and only the positive charges generated in the charge generation layer can be transported to the surface of the photoconductor 1. .

The fifth layer is a charge injection layer, which is a coating layer of a material in which ultrafine particles of SnO ₂ are dispersed in a photocurable acrylic resin, and has a thickness of about 3 μm.

Next, the principle of charging the photoconductor 1 using the magnetic brush charger 2 will be described.

The present invention is a magnetic member such as magnetic conductive particles having a medium resistance or a magnetic sulphate, in which charges are injected to the surface of the photoreceptor 1 having a surface resistance of medium resistance to charge the surface. The magnetic brush charger 2 used in FIG.
As shown in (a), a rotatable non-magnetic conductive sleeve 2a with a diameter of 16 mm contains a fixed magnet roll 2b having a length of 230 mm in the longitudinal direction, and the magnetic conductive particles 2c are generated by the magnetic force of the magnet roll 2b. It is configured to be restrained.

In this embodiment, the magnetic conductive particles 2c as the magnetic member have an average particle diameter of 30 μm, a volume resistance value of 1 × 10 ⁷ Ωcm, a maximum magnetization of 60 Am ² / kg, and a density of 2.2.
Uses g / cm ferrite particles. The distance between the surface of the conductive sleeve 2a and the surface of the photoconductor 1 is set to 500
μm, the amount of ferrite particles on the conductive sleeve 2a is 10 g
In this case, the ferrite particles form a contact surface having a width of about 2 mm between the conductive sleeve 2a and the photoconductor 1, and the magnetic brush charger 2 rotates with a peripheral speed difference with respect to the photoconductor 1. Therefore, about 3 is provided upstream of the conductive sleeve 2a in the rotating direction.
The width of the whole charged contact surface is about 5 mm.
mm. In this case, the particle resistance at the charging contact surface width was 5 × 10 ⁶ Ω when a DC voltage of 100 V was applied.

Next, the structure of the cleaning device 6 will be described.

Residual deposits such as residual toner on the surface of the photoreceptor 1 after the transfer of the toner image are scraped off by the urethane rubber cleaning blade 6a supported by the stainless steel supporting member 6b in FIG. It is collected inside the container 6c.

When an image is formed using the image forming apparatus having the cleaning device 6 having such a structure and the conventional image forming apparatus, the conventional image forming apparatus shows that the magnetic poles of the magnet roll in the conductive sleeve. A magnetic field is formed between the magnetic pole of the magnet roll and the supporting member of the cleaning blade, and a magnetic force is generated between the magnetic pole of the magnet roll and the supporting member of the cleaning blade. Therefore, due to the magnetic force, the ferrite particles on the charging sleeve stay between the support member and the charging sleeve. Therefore, the ferrite particles that contribute to charging are reduced and the charging contact area is reduced, and the charging becomes non-uniform. Further, the chances of contact between the ferrite particles and the photoconductor are reduced, the injection charging ability is reduced, and charging failure occurs. On the other hand, in the image forming apparatus having the cleaning device 6 according to the present embodiment, the cleaning blade 6a is supported by the non-magnetic supporting member 6b, so that the magnet roller 2b and the supporting member 6b for the cleaning blade 6a are supported. Magnetic force does not act between and.
Therefore, the magnetic conductive particles 2c can move smoothly, and the charging contact surface does not decrease,
It is possible to obtain a good image in which no charging failure occurs. Further, since the magnetic conductive particles 2c move smoothly, the charging contact surface can be made uniform and the charging uniformity is improved. <Second Embodiment> Next, a second embodiment will be described with reference to FIG.

The present embodiment is characterized in that a fur brush is used as the cleaning member. FIG.
3 is a schematic configuration diagram showing an image forming apparatus according to a second embodiment. Specifically, the image forming apparatus shown in FIG. 3 is a laser printer utilizing an electrophotographic process. Further, the cleaning device 6 is provided with a fur brush 7 as a cleaning member on the tip side of the non-magnetic conduit 9, and further, in the vicinity of the fur brush 7, residual toner such as residual toner attached to the tips of the fur brush 7 is attached. A stainless flick cover (removal member) 8 for removing the kimono is arranged. The fur brush 7 is formed by flocking rayon on a base cloth into a pile fabric, and spirally winding the outer core with a diameter of 20 mm on a stainless steel core having a diameter of 5 mm. Then, at the rear end of the conduit 9, a fan 1 for sucking residual adhered substances
0 is provided. Further, the fur brush 7 is the photoconductor 1.
The peripheral speed in the direction opposite to the rotation direction of
It is driven and rotated at 000%.

Residual deposits on the surface of the photoconductor 1 after the toner image transfer adheres to the tips of the fur brush 7 which are frictionally charged, and the fur brush 7 collides with the flick cover 8 to cause the tips of the fur brush 7 to come into contact. Leave from. Residual deposits separated from the fur brush 7 are guided by the air flow generated in the conduit 9 by rotating the fan 10 and guided through the conduit 9, and are collected by a filter unit (not shown).

As in the present embodiment, a cleaning device using a core bar of a stainless steel fur brush 7 and a stainless steel flick cover 8 which are made of a non-magnetic material, and an iron for the core bar and flick cover of the fur brush. The following results were obtained when the cleaning device using the above was attached to each of the laser beam printers and the image formation was compared.

That is, it was confirmed that the laser beam printer of the present embodiment is excellent in charging uniformity and can obtain a good image. Further, the fur brush 7 according to the present embodiment is used.
Since there is no such thing as residual adhering matter such as transfer residual toner or paper dust sandwiched between the fur brush 7 and the photoconductor 1, the surface of the photoconductor 1 is not damaged, Good images could be obtained over a long period of time.

In the first embodiment, the direct injection charging method is described as the charging method, but the magnetic brush charging method using discharge can also obtain the same effect as that of the first embodiment. .

In the first embodiment, the stainless steel material is used for the supporting member 6b of the cleaning blade 6a. However, even if a material having a low magnetic susceptibility such as aluminum, glass fiber or polyphenylene sulfide is used, The same effect as the embodiment can be obtained.

[0048]

As described above, according to the present invention,
Since the cleaning device for removing the residual adhering member adhering to the surface of the member to be charged, for example, the supporting member for supporting the cleaning member and the cleaning container to which the supporting member is attached are formed by the non-magnetic member, the magnetic member A magnetic field is not formed between the magnetic pole for restraining the magnetic field and the cleaning device, the contact region contributing to charging is not reduced, the charging uniformity can be ensured, and the charging ability can be reliably ensured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a first embodiment of an image forming apparatus according to the present invention.

2A and 2B show a first embodiment of an image forming apparatus according to the present invention, FIG. 2A is an enlarged sectional view of a magnetic brush charger in contact with a photoconductor, and FIG. ) Are equivalent conceptual diagrams.

FIG. 3 is a schematic configuration diagram showing a second embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

 1 Charged Member (Photosensitive Member) 2 Magnetic Brush Charger 2a Conductive Sleeve 2b Magnet Roll 2c Magnetic Member (Magnetic Conductive Particle) 6 Cleaning Device 6a Cleaning Member 6b Supporting Member 6c Cleaning Container

Claims (7)

[Claims] 1. A magnetic brush charger for applying a voltage to a magnetic member to charge an object to be charged, and a toner image formed on the object to be charged is transferred onto a surface of the object to be charged. An image forming apparatus having a cleaning device for removing residual deposits, wherein at least a part of the cleaning device is formed of a non-magnetic material. 2. The image forming apparatus according to claim 1, wherein the cleaning device includes a cleaning member and a supporting member that supports the cleaning member, and the supporting member is formed of a non-magnetic material. . 3. The cleaning device according to claim 1, wherein a support member that supports the cleaning member is attached to a cleaning container, and the cleaning container is formed of a non-magnetic material. Image forming device. 4. The image forming apparatus according to claim 1, wherein the cleaning member is a cleaning blade. 5. The cleaning member comprises a fur brush, and a removing member for removing residual deposits adhering to the fur brush, according to any one of claims 1 to 3. Image forming device. 6. The image forming apparatus according to claim 5, wherein the removing member is made of a non-magnetic material. 7. The image forming apparatus according to claim 5, wherein the fur brush and the removing member are incorporated in a non-magnetic conduit through which residual deposits pass.